JP6288152B2 - Wireless communication system, wireless base station, wireless terminal, and wireless communication method - Google Patents

Description

  The present invention relates to a wireless communication system, a wireless station, and a wireless communication method.

  In recent years, in the wireless communication system such as a cellular phone system (cellular system), the next generation wireless communication technology has been discussed in order to further increase the speed and capacity of the wireless communication. For example, 3GPP (3rd Generation Partnership Project), a standardization organization, proposes a communication standard called LTE (Long Term Evolution) and a communication standard called LTE-A (LTE-Advanced) based on LTE wireless communication technology. Has been.

  The latest communication standard completed in 3GPP is Release 10 corresponding to LTE-A, which is a significant functional extension of Releases 8 and 9 corresponding to LTE. Currently, discussions are underway toward the completion of Release 11, which is an extension of Release 10. Hereinafter, unless otherwise specified, “LTE” includes, in addition to LTE and LTE-A, other wireless communication systems that extend LTE.

  In 3GPP Release 11, various technologies are discussed. In particular, a problem has been raised regarding the control signal 15a of the downlink radio frame, and active discussions have been made. The outline is described here. In the following, a radio link in the direction from the radio terminal to the radio base station is referred to as an uplink (UL: UpLink), and a radio link in the direction from the radio base station to the radio terminal is referred to as a downlink (DL: DownLink). .

  First, FIG. 1 shows a format of DL subframe 1 up to Release 10 of 3GPP. Basically, data signals for wireless terminals are transmitted in subframe units in the time domain. The DL radio link is constructed on an OFDM (Orthogonal Frequency Division Multiplexing) signal. In FIG. 1 and subsequent figures, the horizontal direction (rightward direction) indicates the frequency axis, and the vertical direction (downward direction) indicates the time axis. The DL subframe 1 is divided into two slots (first slot 11 and second slot 12) in the time axis direction. For example, the length of DL subframe 1 is 1 millisecond, and the length of one slot is 0.5 milliseconds.

  The DL subframe 1 has a control signal area 13 having a specific length (n OFDM symbols, n = {1, 2, 3}) from the beginning in the time axis direction, and a data signal area 14 of the remaining area. It is divided into. The control signal area 13 is an area where a DL control signal 15 corresponding to a physical downlink control channel (PDCCH) is arranged. In FIG. 1, as an example, two DL control signals 15 a and 15 b are arranged in the control signal region 13. On the other hand, the data signal area 14 is an area where a DL data signal 16 corresponding to a physical downlink shared channel (PDSCH) is arranged. In FIG. 1, as an example, two DL data signals 16 a and 16 b are arranged in the data signal area 14. In principle, in this paper, the term “control signal” refers to a DL control signal, and the term “data signal” refers to a DL data signal.

  The DL control signal 15 is arranged in the control signal area 13 according to a predetermined rule. The DL data signal 16 is arranged so as to occupy a certain frequency region (frequency width) in the data signal region 14. The DL data signal 16 is not divided into a plurality of times in the time axis direction in the radio subframe, and occupies a certain frequency region in the subframe.

  The DL data signal 16 in the data signal area 14 is linked to the DL control signal 15a in the control signal area 13. Specifically, an RB allocation (Resource Block Allocation), which is one of parameters included in DCI (Data Control Information) that is DL control information, is a frequency region on the subframe occupied by the data signal 16 (the data signal 16 Radio resources). The DCI is encoded / modulated and converted into a DL control signal 15 and arranged (mapped) in the control signal region 13 to form a PDCCH. The wireless terminal that has received the DL subframe 1 checks whether or not there is a PDCCH (DCI) addressed to itself in the control signal area 13 in the DL subframe 1, and if so, detects the PDCCH addressed to itself. The arrangement information of the DL data signal 16 can be extracted based on the value of the RB allocation included in. In FIG. 1, as an example, the DL control signal 15a is linked to the DL data signal 16a, and the DL control signal 15b is linked to the DL data signal 16b.

  The control signal area 13 is determined to have a maximum of 3 symbols from the top. If the control signal area 13 is further increased, compatibility with an old wireless terminal (such as a wireless terminal that supports only up to Release 8) cannot be maintained. Therefore, it is practical to change the restriction on the maximum three symbols. Absent. However, it is conceivable that the control signal region 13 is deficient due to this restriction. Specifically, for example, when the number of DL data signals 16 is large and the number of corresponding DL control signals 15 is large, it is conceivable that the control signal region 13 is deficient. Moreover, it is conceivable that the control signal region 13 is deficient even when many wireless terminals are located at cell boundaries. This is because, for example, when the wireless terminal is at a cell boundary, it is necessary to set the coding rate applied to the DL control signal 15 to be small. As a result, the size of the DL control signal 15 actually transmitted in the radio space This is because it becomes larger.

  Even in CoMP (Coordinated Multiple Point) transmission / reception that is actively discussed in Release 11 of 3GPP, it is considered that the restriction of the control signal region 13 can be a problem. In CoMP, a plurality of radio base stations cooperate to perform transmission / reception with respect to one radio terminal at the same time. For example, when the wireless terminal is at a cell boundary, the transmission characteristics can be improved based on the transmission diversity effect by applying CoMP. However, when there are many wireless terminals that want to apply CoMP, there are many wireless terminals at the cell boundary, and it is considered that the control signal region 13 tends to be deficient as described above. Therefore, it may be impossible to apply CoMP on the same DL subframe 1 to all wireless terminals to which CoMP is to be applied. In addition, when Multi User MIMO (MU-MIMO) is performed, data signals 16 for a plurality of wireless terminals can be transmitted on the same frequency region, the number of DL control signals 15 to be transmitted is increased, and the control signal region 13 is lacking. Can be a problem.

  Therefore, a new DL subframe 1 is proposed in Release 11 of 3GPP. FIG. 2 shows a format of DL subframe 1 proposed in Release 11.

  In DL subframe 1 in FIG. 2, a control signal area different from conventional control signal area 13 can be set in conventional data signal area 14. This other control signal area is called an extended control signal area 17. In the extended control signal area 17, an extended DL control signal 18 corresponding to an enhanced physical downlink control channel (E-PDCCH) can be arranged.

  The extended control signal area 17 can be used in the same manner as the conventional control signal area 13. Further, the extended DL control signal 18 may include DCI, similarly to the conventional DL control signal 15. Therefore, similarly to the normal DL control signal 15, the extended DL control signal 18 can be associated with the data signal. In FIG. 2, as an example, the extended DL control signal 18 is linked to the DL data signal 16a, and the DL control signal 15 is linked to the DL data signal 16b. The introduction of the extended control signal area 17 can increase the area where DL control information (extended DL control signal 18) can be stored as needed while maintaining compatibility with the conventional wireless terminal. Can be solved.

3GPP TS36.211 V10.4.0 (2011-12) 3GPP R1-113155 “Motivations and scenarios for ePDCCH” (2011-10)

  According to the DL subframe 1 in FIG. 2, the problem of the lack of the control signal region 13 can be solved as described above. However, the DL subframe 1 in FIG. 2 is not necessarily a scheme proposed in consideration of appropriate transmission / reception of the DL data signal 16. As a result of careful examination from this point of view, the inventor found that when the extended control signal area 17 in the DL subframe 1 in FIG. 2 is used, the DL data signal 16 may not be transmitted and received properly. It was.

  The disclosed technique has been made in view of this point, and an object thereof is to provide a wireless communication system capable of appropriately transmitting and receiving the DL data signal 16 using the extended control signal region 17 in the DL subframe 1. To do.

In order to solve the above-described problems and achieve the object, in the disclosed wireless communication system, a wireless base station transmits a wireless signal including a plurality of wireless frames in order to a wireless terminal, and at least one of the plurality of wireless frames is transmitted. The radio frame includes data information and control information, a control area is arranged in the at least one radio frame and a data area is arranged after the control area, and the data area includes the data information and the control information. The other control areas can be arranged in parallel along the time axis, the control information can be arranged in the control area and the other control areas, and the control information includes radio information including information on the size of the data information In the communication system, the radio base station encodes the data information corresponding to the control information based on the control information. An encoding unit that generates encoded data information; and when transmitting the radio signal to the radio terminal based on the size of the data information, if the size of the data information is less than a threshold, a single radio frame When the wireless signal including the encoded data information and the control information corresponding to the encoded data information is transmitted and the size of the data information is greater than or equal to the threshold, the encoding corresponding to the control information An encoded data transmission unit that transmits the radio signal including the control information in a radio frame prior to a radio frame including data information, and the radio terminal corresponds to the control information and the control information. A receiving unit that receives the radio signal including the at least one radio frame including encoded data information from the radio base station; and the received control information. Wherein the size information about the data information, an acquisition unit that acquires a size of the data information, if the size of the acquired said data information is less than the threshold value, the control information same radio frame and the received contained wherein with Gosuru recover the encoded data information received, the received if the size of the acquired said data information is greater than or equal to the threshold value, the radio frame after the radio frame included the control information received in comprising a decoding unit Gosuru recover the encoded data.

  According to one aspect of the wireless communication system, the wireless station, and the wireless communication method disclosed herein, there is an effect that the data signal 16 can be appropriately transmitted and received using the extended control signal region 17 in the DL subframe 1.

FIG. 1 is a diagram illustrating an example of a configuration of a 3GPP Release 10 DL subframe. FIG. 2 is a diagram illustrating an example of a configuration of a DL subframe of 3GPP Release 11. FIG. 3 is a diagram illustrating a problem of 3GPP Release 11 DL subframes. FIG. 4 is a diagram illustrating an example of a network configuration of the wireless communication system according to the first embodiment. FIG. 5 is a diagram illustrating an example of a configuration of a DL subframe according to the first embodiment. FIG. 6 is a diagram illustrating another example of the configuration of the DL subframe according to the first embodiment. FIG. 7 is a diagram illustrating an example of a processing sequence (in the case of the same frame transmission) according to the first embodiment. FIG. 8 is a diagram illustrating an example of the DL control signal and the extended DL control signal according to the first embodiment. FIG. 9 is a diagram illustrating an example of a processing sequence (in the case of next frame transmission) according to the first embodiment. FIG. 10 is an example of a functional configuration diagram of a radio base station in the radio communication system according to the first embodiment. FIG. 11 is an example of a functional configuration diagram of a wireless terminal in the wireless communication system of the first embodiment. FIG. 12 is a diagram illustrating an example of a configuration of a DL subframe according to the second embodiment. FIG. 13 is a diagram illustrating another example of the configuration of the DL subframe according to the second embodiment. FIG. 14 is a diagram illustrating an example of a configuration of a DL subframe according to the third embodiment. FIG. 15 is a diagram illustrating an example of a configuration of a DL subframe according to the fourth embodiment. FIG. 16 is a diagram illustrating an example of a DL control signal and an extended DL control signal according to the fifth embodiment. FIG. 17 is an example of a hardware configuration diagram of a radio base station in the radio communication system of each embodiment. FIG. 18 is an example of a hardware configuration diagram of a wireless terminal in the wireless communication system of each embodiment.

Hereinafter, embodiments of the disclosed wireless communication system, wireless station, and wireless communication method will be described with reference to the drawings. In addition, although demonstrated as separate embodiment for convenience, it cannot be overemphasized that the effect of a combination can be acquired and usefulness can further be heightened by combining each embodiment.
[A] Location of the problem As described above, the inventor can appropriately transmit and receive the data signal 16 by using the extended control signal region 17 in the DL subframe 1 proposed for Release 11 as shown in FIG. I found out that there are cases where I cannot do it. Here, before describing each embodiment, the location of the problem found by the inventors will be described.

  FIG. 3 is a diagram illustrating a problem in Release 11 DL subframe 1. In FIG. 3, as in FIG. 2, as an example, one DL control signal 15 is arranged in the control signal area 13, one extended DL control signal 18 is arranged in the extended control signal area 17, and the data signal area 14 is arranged. Two DL data signals 16a and 16b are arranged. The extended DL control signal 18 is linked to the DL data signal 16a, and the DL control signal 15 is linked to the DL data signal 16b.

  As described above, the DL control signal 15 and the extended DL control signal 18 include the arrangement of each DL data signal 16 (RB allocation), a modulation and coding scheme (MCS), and the like. Therefore, if the demodulation / decoding of the DL control signal 15 and the extended DL control signal 18 is not completed, the DL data signal 16 cannot be extracted and demodulated and decoded. In other words, data cannot be extracted from the DL data signal 16 unless the demodulation and decoding of the DL control signal 15 and the extended DL control signal 18 are completed.

  In the decoding of the DL control signal 15 and the extended DL control signal 18, the DL control signal 15 and the extended DL control signal 18 are demodulated in units of resource elements forming the DL control signal 15 and the extended DL control signal 18. Decode in units. Here, it is assumed that the demodulation and decoding of the DL control signal 15 and the extended DL control signal 18 are completed almost simultaneously with the completion of reception of the DL control signal 15 and the extended DL control signal 18.

  At this time, the DL control signal 15 in the conventional control signal area 13 can be completely received and demodulated / decoded before the DL data signal 16b starts to be received. Accordingly, as shown in FIG. 3, the DL data signal 16b can start to be demodulated and decoded simultaneously with the start of reception. On the other hand, the DL control signal 18 in the extended control signal area 17 is received and demodulated / decoded after a considerable delay from the start of receiving the DL data signal 16a (at the timing when the DL data signal 16a is received). To do. Therefore, as shown in FIG. 3, the start of demodulation / decoding of the DL data signal 16a is considerably delayed compared to the DL data signal 16b.

  There are two major problems due to the delay in the start of demodulation and decoding of the DL data signal 16a. The first problem is a response signal transmission timing in retransmission control (HARQ: Hybrid Automatic Repeat reQuest). When the wireless terminal succeeds in decoding the data addressed to itself, the wireless terminal transmits an ACK signal, which is a response signal indicating successful reception, to the wireless base station. Further, when the wireless terminal fails to decode the data addressed to itself, the wireless terminal transmits a NACK signal that is a response signal indicating a reception failure to the wireless base station. Therefore, the wireless terminal cannot transmit a response signal unless data decoding is completed.

  On the other hand, in the DL transmission of the LTE system, the timing for transmitting a response signal to the DL data is determined within the UL subframe after 4 (4 milliseconds) after the DL subframe 1 including the DL data. ing. Here, if the size of the data signal 16a is large, the demodulation / decoding delay may affect the demodulation / decoding before the timing of transmitting the response signal. In this case, the wireless terminal cannot return an appropriate response signal to the wireless base station. Since the radio base station determines the necessity of data retransmission based on the contents of the response signal, if the response signal is inappropriate, useless retransmission occurs or necessary retransmission is not performed.

  The second problem due to the delay in the start of demodulation / decoding of the data signal 16a is the buffer size for storing data to be processed. The DL data signal 16b corresponding to the DL control signal 15 in the control signal area 13 is simultaneously received and demodulated / decoded. Therefore, a buffer having a relatively small size that can absorb the delay of the demodulation / decoding process is sufficient. On the other hand, the DL data signal 16a corresponding to the extended DL control signal 18 in the extended control signal area 17 has a large delay from the start of reception to the start of demodulation / decoding. A large buffer is needed to store it. Regardless of whether or not the extended control signal area 17 is used, all wireless terminals that can support the extended control signal area 17 need to have such a large-sized buffer. An increase in buffer size is undesirable because it leads to an increase in cost and circuit scale.

  As described above, when the extended control signal area 17 in the DL subframe 1 of Release 11 is used, there is a problem in that the data signal 16 may not be properly transmitted and received.

The disclosed technology is embodied based on the discovery of the above problems by the inventors.
[B] First Embodiment FIG. 4 shows a network configuration of a wireless communication system in the first embodiment. The present embodiment is an embodiment in a radio communication system compliant with LTE. Therefore, some terms and concepts unique to LTE appear. However, it should be noted that this embodiment is merely an example, and can be applied to a wireless communication system compliant with a communication standard other than LTE.

  The radio communication system illustrated in FIG. 4 includes a radio base station 2 (eNB: evolved Node B), a radio terminal 3 (UE: User Equipment), and the like. In the following description, the radio base station 2 and the radio terminal 3 may be collectively referred to as radio stations.

  A wireless network between the wireless base station 2 and the wireless terminal 3 is referred to as a wireless access network 4. The wireless base stations 2 are connected by a wired or wireless network (transmission network) called a backhaul network 5. The backhaul network 5 is a network that connects between the radio base stations 2 and connects the radio base station 2 and the core network. The radio base station 2 can communicate with a device connected to the core network via the backhaul network 5. A non-illustrated MME (Mobility Management Entity), SAE-GW (System Architecture Evolution Gateway) and the like are connected to the core network. The LTE network is sometimes referred to as an EPS (Evolved Packet System). The EPS includes an eUTRAN (Evolved Universal Terrestrial Radio Network) that is a radio access network and an EPC (Evolved Packet Core) that is a core network. The core network is sometimes called SAE (System Architecture Evolution).

  A wireless base station 2 (also referred to simply as a base station) in FIG. 4 is a device that performs wireless communication with the wireless terminal 3 via the wireless access network 4 and is connected to the backhaul network 5. The radio base station 2 transmits and receives data to and from a subordinate radio terminal 3 (also referred to as a connected radio terminal), and performs various controls on the radio terminal 3 by exchanging various control information with the subordinate radio terminal 3. The radio base station 2 relays data with the other radio base station 2 via the backhaul network 5 and also cooperates with the other radio base station 2 by exchanging various control information. Can do.

  The radio base station 2 exchanges various control information with a control device such as an MME connected to the core network ahead of the backhaul network via the backhaul network 5. Also, the radio base station 2 relays data received from the subordinate radio terminal 3 to a relay device such as SAE-GW connected to the core network, and also receives data received from a relay device such as SAE-GW. Relay to the wireless terminal 3.

  The wireless base station 2 may be connected to the backhaul network 5 by wire or may be connected wirelessly. Further, the wireless base station 2 may project a wireless communication function with the wireless terminal 3 via the wireless access network 4 as a separate device, RRH (Remote Radio Head), and may connect them with a wire. Further, the radio base station 2 may be a base station of various scales in addition to a small base station (including a micro base station, a femto base station, etc.) such as a macro base station and a pico base station. When a relay station that relays wireless communication between the base station and the wireless terminal 3 is used, the relay station (transmission / reception with the wireless terminal and its control) may also be included in the wireless base station 2 of this paper. .

  Incidentally, a “cell” is a range covered by the radio base station 2 in order for the radio terminal 3 to transmit and receive radio signals (strictly speaking, there are UL cells and DL cells. Moreover, radio base stations are also included. In the case where the second antenna is a sector antenna, a cell is usually formed for each sector, and further, a cell is formed for each radio carrier in LTE Release 10 or later.) However, the radio base station 2 and the cell correspond to some extent. Therefore, in the description of this paper, “cell” and “radio base station” may be read as appropriate for convenience.

  On the other hand, the wireless terminal 3 (also referred to as a wireless mobile terminal, a mobile terminal, or simply a terminal. Also referred to as a user device, a subscriber station, a mobile station, etc.) in FIG. Is a device that performs wireless communication with the wireless base station 2 via the network. The radio terminal 3 is connected to one radio base station 2, and when the radio status changes due to movement or the like, the radio base station 2 to be connected is switched by handover. Here, “connected” indicates that the wireless terminal 3 is registered (Attach) to the wireless base station 2, but may simply be interpreted as meaning that communication is being performed. The radio base station 2 to which the radio terminal 3 is connected is called a connected radio base station 2 or a serving cell. The wireless terminal 3 transmits and receives data by wireless communication with the connected wireless base station 2 and receives various controls by exchanging various control information through wireless communication with the connected wireless base station 2.

  The wireless terminal 3 may be a terminal such as a mobile phone, a smartphone, a PDA (Personal Digital Assistant), or a personal computer (Personal Computer). When a relay station that relays wireless communication between the wireless base station 2 and the terminal is used, the relay station (transmission / reception with the wireless base station and control thereof) may be included in the wireless terminal 3 of this paper. .

  The radio communication system according to the present embodiment uses an OFDMA (Orthogonal Frequency Division Multiple Access) system as a DL radio access system. Further, an SC-FDMA (Single Carrier Frequency Multiple Access) system is used as an uplink radio access system.

  In the radio communication system according to the present embodiment, both the DL radio signal and the UL radio signal are composed of radio frames (also simply referred to as frames) having a predetermined length (for example, 10 milliseconds). Further, one radio frame is composed of a predetermined number (for example, 10) of radio subframes (also simply referred to as subframes) each having a predetermined length (for example, 1 millisecond). Each subframe is composed of 12 or 14 symbols. Note that “frame” and “subframe” are merely terms indicating a processing unit of a radio signal, and therefore, these terms may be appropriately read below.

  Several physical channels are defined in the LTE physical layer. For example, the DL physical channel includes a downlink shared channel (PDSCH) used for transmission of the DL data signal 16 and the like, and a downlink control channel (PDCCH: Physical Downlink Control Channel) used for transmission of the DL control signal 15. ) Etc. The DL control signal 15 here is for transmitting control information directly required for PDSCH transmission, and is a control signal at the physical layer (or Layer 1) level. On the other hand, the upper layer control signal is transmitted using PDSCH. As described above, the size of the control signal area 13 in the DL subframe 1 is variable (1 to 3 symbols from the beginning of the DL subframe 1). There is also a PCFICH (Physical Control Format Indicator Channel) for notifying the size. On the other hand, UL physical channels include uplink shared channels (PUSCH) used for transmission of UL data signals, response signals for DL data signals 16 and results of DL radio characteristics measurement results, etc. There is an uplink control channel (PUCCH: Physical Uplink Control Channel) used for transmission.

  In addition to the DL data signal 16 and the DL control signal 15, the DL subframe 1 is also mapped with a DL reference signal for demodulating the DL data signal 16 and the DL control signal 15, and for measuring a radio characteristic. In addition to the UL data signal and the UL control signal, the UL subframe is also mapped with a UL reference signal for demodulating the UL signal and for measuring the radio characteristics.

  Next, a frame configuration in the first embodiment will be described with reference to FIG.

  FIG. 5 shows two DL subframes 1 that are continuous in time. In FIG. 5, the previous DL subframe 1 on the time axis is referred to as an Nth DL subframe 1a (meaning Nth DL subframe 1). Also, the DL subframe 1 that is later on the time axis is referred to as the (N + 1) th DL subframe 1b (meaning the (N + 1) th DL subframe 1).

  In FIG. 5, an extended control signal area 1a7 is set in the Nth DL subframe 1a, and two extended DL control signals 1a8a and 1a8b are arranged in the extended control signal area 1a7. Extended DL control signal 1a8a is arranged so as to be accommodated in first slot 1a1 of Nth DL subframe 1a. On the other hand, the extended DL control signal 1a8b is arranged in the second slot 1a2 (outside the first slot 1a1) of the Nth DL subframe 1a. In addition, one DL data signal 1a6 is arranged in the data signal area 1a4 of the Nth DL subframe 1a, and one DL data is also in the N + 1th DL subframe 1b which is the next DL subframe 1. Signal 1b6 is arranged. In the following description, for example, a plurality of extended DL control signals 1a8a and 1a8b in the Nth DL subframe 1a are collectively referred to as “extended DL control signal 1a8”, or extended DL control signals are collectively referred to as “extended DL control signal 1a8b”. In some cases, reference numerals (alphabetic characters) may be omitted for a plurality of the same objects, such as “DL control signal 18”.

  In FIG. 5, the extended DL control signal 1a8a is controlled by the DL data signal 1a6 arranged in the Nth DL subframe 1a. That is, the extended DL control signal 1a8a targets the DL data signal 1a6 on the same DL subframe 1 as the DL subframe 1 in which the extended DL control signal 1a8a is arranged. On the other hand, the extended DL control signal 1a8b is controlled by the DL data signal 1b6 arranged in the (N + 1) th DL subframe 1b. That is, the extended DL control signal 1a8b is controlled by the DL data signal 1b6 on the DL subframe next to the DL subframe in which the extended DL control signal 1a8b is arranged.

  In summary, the extended DL control signal 1a8a arranged in the first slot 1a1 of the extended control signal area 1a7 is the same DL subframe 1 (Nth DL DL) as the DL subframe 1 in which the control signal 1a8a is arranged. The DL data signal 1a6 arranged in the subframe 1a) is set as a control target. On the other hand, the extended DL control signal 1a8b arranged in the second slot 1a2 of the extended control signal area 1a7 is the DL subframe (N + 1 DL subframe) next to the DL subframe in which the extended DL control signal 1a8b is arranged. The DL data signal 1b6 arranged in the frame 1b) is set as a control target.

  With the frame configuration as shown in FIG. 5, the decoding delay of the extended DL control signal 18 is suppressed as compared with the prior art shown in FIG. First, since the extended DL control signal 1a8a in the first slot 1a1 can be demodulated / decoded before the reception of the first slot 1a1 is completed, the DL data signal 1a6 in the same subframe is demodulated / decoded with a relatively small delay. it can. Further, since the extended DL control signal 1a8b in the second slot 1a2 can be demodulated / decoded before the reception of the second slot 1a2 is completed, the DL data signal 1b6 in the next subframe can be demodulated / decoded without delay. Therefore, the delay of the DL data signal 16 demodulation / decoding start is eliminated or suppressed, so that the above-described retransmission control and buffer problems are reduced.

  In applying DL subframe 1 in FIG. 5, the DL data signal 1a6 in the same subframe to be controlled by the extended DL control signal 1a8a in the first slot 1a1 is limited to a small data size. Is desirable. This is because the smaller the data size, the shorter the time required for demodulation / decoding, so that the influence of the delay of the demodulation / decoding start on the DL data signal 1a6 based on the demodulation / decoding delay of the extended DL control signal 1a8a can be reduced.

  On the other hand, the DL data signal 1b6 in the next frame to be controlled by the extended DL control signal 1a8b in the second slot 1a2 may have a large data size. This is because the DL data signal 1b6 has no delay in starting demodulation and decoding.

  In the above description, the extended DL control signal 1a8 in the extended control signal area 1a7 is mainly described. However, as shown in FIG. 6, the DL control signal 1a5 in the control signal area 1a3 may be used together. Not too long. However, the case where the DL control signal 1a5 (or the control signal area 1a3 itself) of the control signal area 1a3 is not used is not excluded. That is, the control signal region 1a3 is not used, and only the extended control signal region 1a7 may be used.

  In the above description, the handling of the extended DL control signal 1a8a in the first slot 1a1 and the extended DL control signal 1a8b in the second slot 1a2 is described, but the handling of the extended DL control signal 1a8 across two slots is described. May be determined separately. For example, the extended DL control signal 1a8 across two slots may be regarded as being disposed in the first slot 1a1, or may be regarded as being disposed in the second slot 1a2. , May be ignored (handled as invalid).

  Since the control signal region 1a3 (corresponding to PDCCH) extends over the entire transmission band, it is known that there are various restrictions. For example, Release 8 of 3GPP introduces inter-cell interference coordination (ICIC: Inter-Cell Interference Coordination). This is because a specific data area in a certain cell is not used for data transmission in RB units (blank signal), and it is coordinated between adjacent cells, so that it is not affected by adjacent cells so much between cells. Data transmission can be performed. ICIC can be applied to the DL data signal 1a6 without any problem. However, since the control signal area 1a3 extends over the entire DL transmission band, a specific area in the control signal area 1a3 cannot be a blank signal in units of RBs. Therefore, ICIC cannot be applied to the DL control signal 1a5 in the control signal region 1a3.

  On the other hand, the extended control signal area 1a7 (corresponding to E-PDCCH) can be transmitted only in a certain frequency bandwidth on the data area, like the data signal 1a6a. Therefore, ICIC can be applied to the DL control signal 1a5 in the extended control signal region 1a7. Therefore, when it is desired to suppress interference between base stations, it is possible to use only the extended control signal region 1a7 (E-PDCCH) without using the control signal region 1a3 (PDCCH).

  A processing sequence in the first embodiment will be described with reference to FIGS.

  FIG. 7 is a diagram illustrating an example of a processing sequence when the extended DL control signal 1a8 and the DL data signal 1a6 to be controlled are transmitted in the same DL subframe 1a (when transmitted).

  First, in FIG. 7, before S101, the radio base station 2 shows the arrangement of the extended control signal area 1a7 in the DL subframe 1 (frequency band to which the enhanced signal area is assigned) by a DL signal (not shown). Information is transmitted to the wireless terminal 3. Thereby, the radio | wireless terminal 3 can recognize beforehand arrangement | positioning of the extended control signal area | region 1a7.

  In S101 of FIG. 7, DL data is generated in the radio base station 2. For example, DL data is generated when an audio signal, data, or the like is transmitted from another wireless terminal to the subordinate wireless terminal 3, or when a server on the Internet transmits data to the wireless terminal 3. Furthermore, in order for the radio base station 2 to change the operation mode of the radio terminal 3, an upper layer level control signal including the contents of the operation mode may be transmitted as DL data.

  In S102, the radio base station 2 arranges a control signal corresponding to DL control information (DCI) transmitted accompanying transmission of DL data in the control signal area 1a3 (corresponding to PDCCH) or extends the control signal area. It is determined whether to arrange in the control signal area 1a7 (corresponding to E-PDCCH). In other words, the radio base station 2 determines whether to arrange the DL control information (DCI) as the DL control signal 1a5 (corresponding to PDCCH) or the extended DL control signal 1a8 (corresponding to E-PDCCH). This determination may be made according to arbitrary rules. As an example, when the control signal area 1a3 has a large free area, the DL control signal 1a5 corresponding to the DL control information is arranged in the control signal area 1a3, and when the control signal area 1a3 has a small free area, it is included in the DL control information. The corresponding extended DL control signal 1a8a can be arranged in the control signal area extended control signal area 1a7. Assume that the radio base station 2 in FIG. 7 determines to transmit the extended DL control signal 1a8 in the extended control signal area 1a7 in S102. In S102, when the radio base station 2 decides to transmit the DL control signal 1a5 in the control signal region 1a3, a general DL data transmission process may be performed, and the description is omitted.

  Next, in S103, the radio base station 2 sets the DL subframe 1 for transmitting DL data as the same DL subframe 1a as the extended DL control signal 1a8 (same transmission) or the next DL subframe of the extended DL control signal 1a8. The frame 1b is determined (separate transmission). This determination may be made according to arbitrary rules. As an example, when the DL data size (for example, bit length or byte length) is less than a predetermined value, the data is sent simultaneously, and when the DL data size is larger than the predetermined value, it is sent separately. Assume that the radio base station 2 in FIG. 7 determines to transmit the extended DL control signal 1a8 and the DL data (corresponding to the DL data signal 1a6) in S103.

  In S104, the radio base station 2 determines a DL radio resource for transmitting DL data to the radio terminal 3 (performs radio resource scheduling). At this time, the radio base station 2 determines a radio resource for the data signal 1a6 in the same DL subframe 1 as the extended DL control signal 1a8 based on the determination in S103. The DL radio resource determination may be performed in accordance with a general method that considers the characteristics of the wireless terminal 3, the number of terminals to be scheduled at the same time, and the like, and will not be described in detail.

  In S <b> 105, the radio base station 2 transmits a DL subframe 1 including DL data to the radio terminal 3. At this time, based on the determination in S103, the radio base station 2 transmits DL data (corresponding DL data signal 1a6) and an extended DL control signal 1a8 whose control target is the DL data in the same DL subframe 1 (Send together). This DL subframe 1 is defined as an Nth DL subframe 1a.

  The N-th DL subframe 1a transmitted from the radio base station 2 in S105 will be described in detail. In the N-th DL subframe 1a, the radio base station 2 arranges the extended DL control signal 1a8 corresponding to the DL data in the control signal area extended control signal area 1a7 based on the determination in S102. At this time, the radio base station 2 further arranges the extended DL control signal 1a8 in the N-th DL subframe 1a according to the extension control signal 1a8 arrangement rule in the case of the transmission based on the determination of S103. In the first embodiment, the extended DL control signal 1a8 is arranged so as to be within the first slot 1a1 in the control signal area extended control signal area 1a7 of the Nth DL subframe 1a. This is an extended DL control signal arrangement rule. On the other hand, arranging the extended DL control signal 1a8 so as to be within the second slot 1a2 in the extended control signal region 1a7 of the Nth DL subframe 1a is an extended DL control signal arrangement rule in the case of separate transmission. Based on the determination in S103, the radio base station 2 in FIG. 7 arranges the extended DL control signal 1a8 so as to be within the first slot 1a1 in the extended control signal region 1a7 in the Nth DL subframe 1a.

  Furthermore, in the Nth DL subframe 1a, the radio base station 2 arranges the DL data signal 1a6 that is the control target of the extended DL control signal 1a8 arranged in advance based on the determination in S104. Thus, the Nth DL subframe 1a includes the DL data signal 1a6 and the extended DL control signal 1a8 corresponding to the DL data signal 1a6.

  In S105, the wireless terminal 3 receives the Nth DL subframe 1a. In S106, the radio terminal 3 demodulates and decodes the received DL control signal 1a5 and extended DL control signal 1a8 of the Nth DL subframe 1a. At this time, the wireless terminal 3 is basically based on all the DL control signals 1a5a and the extended DL control signal 1a8 arranged in the control signal area 1a3 and the extended control signal area 1a7 based on a predetermined process (details are omitted). However, in all DL subframes 1, a check process is performed to check whether there is a DL control signal 1a5 and an extended DL control signal 1a8 for both the control signal area 1a3 and the extended control signal area 1a7. It is also possible to avoid this. For example, the radio base station 2 preliminarily prevents the radio terminal 3 from performing demodulation / decoding processing on the control signal region 1a3 in a specific DL subframe within a 10 ms long radio frame. It is possible to instruct using a layer control signal. Similarly, the radio base station 2 may prevent the radio terminal 3 from performing demodulation / decoding processing on the extended control signal area 1a7 in a specific DL subframe within a radio frame having a length of 10 milliseconds. It is possible to instruct using the upper layer control signal.

  Here, FIG. 8 shows an example of the format of the DL control information carried by the DL control signal 1a5 or the extended DL control signal 1a8 in the present embodiment. The DL control information shown in FIG. 8 uses DCI (Data Control Information) which is DL control information defined by LTE as it is. The DL control signal 1a5 or the extended DL control signal 1a8 is generated by encoding and demodulating the DCI that is the DL control information.

  The DL control information (DCI) in FIG. 4 includes a 16-bit CRC (Cyclic Redundancy Check) scrambled with a 16-bit RNTI (Radio Network Temporary Identifier) that is an identifier of the destination wireless terminal 3 of the DL control signal 1a5a, RB allocation (Resource block assignment) which is information indicating the allocated radio resource (to which resource block (RB) the data is allocated on the subframe), MCS (Modulation and) indicating the data modulation and coding scheme Coding Scheme). In the figure, CRC scrambled with RNTI is indicated as RNTI for convenience. Besides these, DCI includes parameters such as RV (Redundancy Version), NDI (New Data Indicator), HARQ (Hybrid Automatic Repeat reQuest) processing number, PUCCH power control, etc., but details are omitted.

  The DL control information (DCI) has several formats, and it is possible to identify whether the control target is the DL data signal 1a6 or the UL data signal according to the format. For example, in DCI defined by LTE, format 0 controls PUSCH, that is, UL data. Each of the formats 1A, 1B, 1C, 1D, 2, 2A, 2B, and 2C is determined to control PDSCH, that is, DL data. The type of DCI format used varies depending on whether or not spatial multiplexing is performed.

  Returning to the description of S106 in FIG. Based on the format of DL control information (DCI) obtained by demodulating and decoding the detected DL control signal 1a5 or extended DL control signal 1a8, the wireless terminal 3 applies the UL control signal to the DL control signal 1a5 or DL control signal 1a8. Or DL data signal 1a6 is recognized (detected). Further, the wireless terminal 3 recognizes (detects) the DL control information addressed to itself based on the RNTI of the DL control information. Since the 16-bit CRC in the DL control information is scrambled with its own identification number (RNTI), the contents of the DL control information for a certain terminal cannot be decoded by other terminals unless an unexpected error occurs.

  In S106, when the detected DL control information (DCI) addressed to itself is based on the extended DL control signal 1a8, the wireless terminal 3 determines the extended DL control signal 1a8 based on the arrangement of the extended DL control signal 1a8. Whether the control object is the DL data signal 1a6 of the same DL subframe 1a or the DL data signal 1b6 of the next DL subframe 1b. In the wireless terminal 3 in the first embodiment, when the extended DL control signal 1a8 is arranged in the first slot 1a1 of the extended control signal area 1a7, the control target of the extended DL control signal 1a8 is the same frame (that is, the Nth The DL data signal 1a6 in the subframe 1a) is determined. On the other hand, when the extended DL control signal 1a8 is arranged in the second slot 1a2 of the extended control signal area 1a7, the control target of the extended DL control signal 1a8 is the data signal in the next frame (that is, the (N + 1) th subframe 1b). It is determined as 1b6. In the example of FIG. 7, since the extended DL control signal 1a8 is arranged in the first slot 1a1 of the extended control signal area 1a7 (S105), the wireless terminal 3 controls the extended DL control signal 1a7 in the same frame. It is determined that it is (Nth subframe 1a). In S106, if the detected DL control information (DCI) addressed to itself is based on the DL control signal 1a5, the wireless terminal 3 controls the DL control signal 1a5 for the DL data signal 1a6 of the same subframe. Judge.

  In S107, the wireless terminal 3 demodulates and decodes the DL data signal 1a6 that is the control target of the extended DL control signal 1a8 detected in S106. At this time, the wireless terminal 3 in FIG. 7 demodulates and decodes the DL data signal 1a6 in the Nth DL subframe 1a based on the determination in S106. The wireless terminal 3 extracts the DL data signal 1a6 from the Nth DL subframe 1a based on the RB allocation included in the DL control information (DCI) obtained from the received extended DL control signal 1a8, and performs the DL based on the MCS. The data signal 1a6 is demodulated and decoded.

  In S108, the radio terminal 3 transmits a response signal to the received DL data signal 1a6 to the radio base station 2. Here, as an example, it is assumed that the transmission timing of the response signal is determined to be the UL subframe four times after the DL subframe 1 that has received the DL data signal 1a6. In the example of FIG. 7, since the DL data signal 1a6 is received in the Nth DL subframe 1a, a response signal is transmitted in the (N + 4) UL subframe. The type (content) of the response signal is based on the decoding result of S107. If no error is detected in decoding, the response signal is an ACK signal. On the other hand, when an error is detected in decoding, the response signal is a NACK signal. On the other hand, the radio base station 2 determines whether or not the data signal 1a6 needs to be retransmitted by receiving the response signal.

  In S108, the radio terminal 3 can determine the UL radio resource when transmitting the response signal in the UL subframe as follows. For example, when UL wireless resource allocation information is included in the Nth DL subframe, the wireless terminal 3 can transmit a response signal based on this information. In addition, when UL radio resource allocation information is not included in the Nth DL subframe, for example, the radio terminal 3 can use the UL radio resource notified in advance by a higher layer control signal. As another example, when UL radio resource allocation information is not included in the Nth DL subframe, the radio terminal 3 uses the DL radio resource used to transmit the enhanced DL control signal included in the Nth DL subframe. UL radio resources can also be determined based on (can be determined in association with a CCE (Control Channel Element) identification number).

  Next, a case will be described in which the DL data signal 1b6 to be controlled by the extended DL control signal 1a8 is transmitted in the DL subframe 1b next to the DL subframe 1a including the extended DL control signal 1a8 (separately transmitted). . FIG. 9 is a diagram illustrating an example of a processing sequence when the extended DL control signal 1a8 and the DL data signal 1b6 to be controlled by the extended DL control signal 1a8 are separately transmitted.

  The process up to S202 in FIG. 9 is the same as that up to S102 in FIG.

  In S203 of FIG. 9, the radio base station 2 sets the DL subframe 1 for transmitting DL data to the same DL subframe 1a as the extended DL control signal 1a8 (same transmission) as in S103 of FIG. The next DL subframe 1b of the extended DL control signal 1a8 is determined (separate transmission). Assume that the radio base station 2 in FIG. 9 determines to transmit separately the extended DL control signal 1a8 and the DL data signal 1b6 in S203.

  In S204, the radio base station 2 determines a DL radio resource for transmitting DL data to the radio terminal 3 (performs radio resource scheduling). At this time, the radio base station 2 determines radio resources for the DL data signal 1b6 in the DL subframe 1b next to the DL subframe 1a that transmits the extended DL control signal 1a8 based on the determination in S203. The DL radio resource determination may be performed in accordance with a general method, and thus detailed description thereof is omitted.

  In S205, the radio base station 2 transmits the DL subframe 1a including the extended DL control signal 1a8 to the radio terminal 3. This DL subframe 1a is defined as an Nth DL subframe 1a. At this time, based on the determination in S203, the radio base station 2 does not transmit the DL data signal 1b6 to be controlled by the extended DL control signal 1a8 in the Nth DL subframe 1a.

  Here, in the Nth DL subframe 1a, the radio base station 2 arranges the extended DL control signal 1a8 corresponding to the DL data in the extended control signal region 1a7 based on the determination in S202. At this time, the radio base station 2 further arranges the extended DL control signal 1a8 in the DL subframe 1 in accordance with the extended DL control signal arrangement rule in the case of separate transmission based on the determination in S203. In the first embodiment, the extended DL control signal 1a8 is arranged so as to be within the first slot 1a1 in the extended control signal region 1a7 of the Nth DL subframe 1a. It becomes a placement rule. On the other hand, arranging the extended DL control signal 1a8 so as to be within the second slot in the extended control signal region 1a7 of the Nth DL subframe 1a is an extended DL control signal arrangement rule in the case of separate transmission. Based on the determination in S203, the radio base station 2 in FIG. 9 arranges the extended DL control signal 1a8 so as to be within the second slot 1a2 in the extended control signal region 1a7 in the Nth DL subframe 1a.

  Note that, in the Nth DL subframe 1a, the radio base station 2 does not arrange DL data corresponding to the previously arranged extended DL control signal 1a8 based on the determination in S203. As a result, the Nth DL subframe 1a does not include DL data but includes an extended DL control signal 1a8 corresponding to the DL data.

  In S205, the wireless terminal 3 receives the Nth DL subframe 1a. In S206, the wireless terminal 3 demodulates and decodes the received extended DL control signal 1a8 of the Nth DL subframe 1a. At this time, the wireless terminal 3 performs predetermined steps (details are omitted) on the DL control signal 1a5 and the extended DL control signal 1a8 arranged in the control signal region 1a3 and the extended control signal region 1a7 in the same manner as S206 in FIG. Demodulate and decode based on Based on the format of DL control information (DCI) obtained by demodulating and decoding the detected DL control signal 1a5 or extended DL control signal 1a8, the wireless terminal 3 applies the UL control data 1a5 or the extended DL control signal 1a8 to the UL data. Or DL data is recognized (detected). Further, the wireless terminal 3 recognizes (detects) the extended DL control information 8 addressed to itself based on the RNTI of the DL control information.

  In S206, when the detected DL control information (DCI) addressed to itself is based on the extended DL control signal 1a8, the wireless terminal 3 determines the extended DL control signal 1a8 based on the arrangement of the extended DL control signal 1a8. Is the data signal 1a6 of the same DL subframe 1a or the data signal 1b6 of the next DL subframe 1b. In the wireless terminal 3 in the first embodiment, when the extended DL control signal 1a8 is arranged in the first slot 1a1 of the extended control signal area 1a7, the control target of the extended DL control signal 1a8 is the same frame (that is, the Nth The data signal 1a6 in the DL subframe 1a) is determined. On the other hand, when the extended DL control signal 1a8 is arranged in the second slot 1a2 of the extended control signal area 1a7, the control target of the extended DL control signal 1a8 is the data signal in the next frame (that is, the (N + 1) th subframe 1b). It is determined as 1b6. In the example of FIG. 9, since the extended DL control signal 1a8 is arranged in the first slot 1a2 of the extended control signal area 1a7 (S205), the wireless terminal 3 determines that the control target of the extended DL control signal 1a8 is the next frame. It is determined that it is (N + 1th subframe 1b).

  In S207, the radio base station 2 transmits the DL subframe 1 including the DL data signal 1b6 generated by encoding and modulating the DL data to the radio terminal 3. This radio frame becomes the (N + 1) th subframe 1b that is the next DL subframe of the Nth DL subframe 1a that is the DL subframe that has transmitted the enhanced DL control signal 1a8 based on the determination in S203. In the (N + 1) th subframe 1b, the radio base station 2 transmits the DL data signal 1b6 based on the radio resource determined in S204.

  In S207, the wireless terminal 3 receives the (N + 1) th DL subframe 1b. In S208, the wireless terminal 3 demodulates and decodes the DL data signal 1b6 that is the control target of the extended DL control signal 1a8 detected in S206. At this time, the wireless terminal 3 in FIG. 9 demodulates and decodes the DL data signal 1b6 in the (N + 1) th DL subframe 1b based on the determination in S206. The wireless terminal 3 extracts the DL data signal 1b6 from the (N + 1) th DL subframe 1b based on the RB allocation included in the DL control information (DCI) obtained from the received extended DL control signal 1a8, and performs the DL based on the MCS. The data signal 1b6 is demodulated and decoded.

  In S209, the radio terminal 3 transmits a response signal to the received DL data signal 1b6 to the radio base station 2. Here, as an example, it is assumed that the transmission timing of the response signal is determined to be the UL subframe four times after the DL subframe 1 that has received the DL data signal 1b6. In the example of FIG. 9, since the DL data signal 1b6 is received in the (N + 1) th DL subframe 1b, a response signal is transmitted in the (N + 5) th UL subframe. Since the type (contents) of the response signal and the determination of the UL radio resource to be used when transmitting the response signal are the same as S108 in FIG.

  Based on FIGS. 10-11, each apparatus structure in 1st Embodiment is demonstrated.

  FIG. 10 is a diagram illustrating an example of a functional configuration of the radio base station 2 in the first embodiment. The radio base station 2 includes, for example, a DL data information generation unit 201, a DL data signal encoding / modulation unit 202, a scheduler unit 203, a DL control information generation unit 204, a DL control signal encoding / modulation unit 205, and a DL reference signal generation. Unit 206, DL subframe generation unit 207, DL radio transmission unit 208, UL radio reception unit 209, UL subframe analysis unit 210, UL reference signal processing unit 211, UL control signal demodulation / decoding unit 212, UL data signal demodulation A decoding unit 213 and a transmission network communication unit 214 are provided. The scheduler unit 203 includes a control signal region determining unit 2031, a subframe determining unit 2032, and a resource determining unit 2033.

  The DL data information generation unit 201 generates DL data information and inputs the DL data information to the DL data encoding / modulation unit 201. In addition, when the DL data information generation unit 201 generates DL data, the DL data information generation unit 201 requests the scheduler unit 203 to perform scheduling for transmitting the DL data information. DL data encoding / modulation section 202 encodes and modulates DL data information based on the encoding scheme / modulation scheme input from scheduler section 203 to generate DL data signal 16, and DL subframe generation section Input to 207.

  The scheduler unit 203 performs scheduling of radio resources used for radio communication and performs various controls associated with the scheduling of radio resources.

  When DL data is generated, control signal region determining section 2031 places a control signal corresponding to DL control information transmitted accompanying the transmission of DL data in control signal region 1a3 (corresponding to PDCCH). Or whether to arrange in the extended control signal area 1a7 (corresponding to E-PDCCH). In other words, the control signal region determination unit 2031 determines whether to arrange the DL control information (DCI) as the DL control signal 1a5 (corresponding to PDCCH) or the extended DL control signal 1a8 (corresponding to E-PDCCH). To do. This determination may be made according to arbitrary rules. As an example, when the control signal area has a large free area, the DL control signal 1a5a corresponding to the DL control information is arranged in the control signal area 1a3, and when the control signal area 1a3 has a small free area, the extended DL control signal 1a8. Can be arranged in the extended control signal area 1a7.

  DL subframe for transmitting DL data when subframe determining section 2032 determines that extended DL control signal 1a8 (corresponding to E-PDCCH) is arranged in extended control signal area 1a7 by control signal area determining section 2031 1 is determined to be the same DL subframe 1a as the extended DL control signal 1a8 (same transmission) or the next DL subframe 1b of the extended DL control signal 1a8 (separate transmission). This determination may be made according to arbitrary rules. As an example, when the DL data size (for example, bit length or byte length) is less than a predetermined value, the data is sent simultaneously, and when the DL data size is larger than the predetermined value, it is sent separately.

  The resource determination unit 2033 determines a DL radio resource for transmitting DL data to the radio terminal 3 (performs radio resource scheduling). At this time, the resource determination unit 2033 determines a radio resource for the data signal 16 in the DL subframe 1 that is the same as or next to the extension control signal 1a8 based on the determination of the subframe determination unit 2032. The DL radio resource determination may be performed in accordance with a general method, and thus detailed description thereof is omitted.

  The scheduler unit 203 outputs the scheduler results including the determinations by the control signal region determination unit 2031, the subframe determination unit 2032, and the resource determination unit 2033, the DL data signal encoding / modulation unit 202, the DL control information generation unit 204, and the DL reference Input to the signal generator 206.

  The DL control information generation unit 204 generates DL control information based on the scheduling result input from the scheduler unit 203 and inputs the DL control information to the DL control signal encoding / modulation unit 205. As an example, the DL control information generation unit 204 generates DCI shown in FIG. 8 based on the input scheduling result. The DL control information generation unit 204 sets a DCI RB allocation value based on the determined radio resource included in the scheduling result input from the scheduler unit 203. Also, the DL control information generation unit 204 sets the wireless terminal 3 identifier input from the scheduler to the RNTI value, and sets the modulation scheme / coding scheme to the MCS value. DL control signal encoding / modulating section 205 encodes and modulates DL control information based on the modulation scheme / coding scheme instructed by the scheduler section to generate DL control information 1a5 or extended DL control signal 1a8. , Input to the DL subframe generation unit 207.

  The DL reference signal generation unit 206 generates a DL reference signal and inputs it to the DL subframe generation unit 207.

  The DL subframe generation unit 207 arranges the DL data signal 16 after encoding and modulation, the DL control signal 1a5 or the extended DL control signal 1a8 corresponding to the DL data signal 16 and the DL reference signal in the DL subframe 1 ( DL subframe 1 is generated. The DL data signal 16 is arranged in the DL subframe 1 and forms a physical downlink shared channel (PDSCH). The DL control signal 1a5 is arranged in the DL subframe 1 and forms a physical downlink control channel (PDCCH). The extended DL control signal 1a8 is arranged in the DL subframe 1 and forms an extended physical downlink control channel (E-PDCCH). The DL reference signal is arranged in the DL subframe 1 based on a different pattern for each cell.

  The DL subframe generation unit 207 performs mapping of each DL signal based on the scheduling result input from the scheduler unit 203. That is, the DL subframe generation unit 207 maps each signal to a radio resource (RB) defined in the scheduling result input from the scheduler unit 203.

  The operation of the DL subframe generation unit 207 will be specifically described.

  Based on the determination of the subframe determination unit 2032, the DL subframe generation unit 207 maps the DL data signal 16 and the extended DL control signal 1 a 8 corresponding to the DL data signal 16 as follows.

  First, the processing of the DL subframe generation unit 207 when the subframe determination unit 2032 determines to transmit (send together) the DL data signal 1a6 and the corresponding extended DL control signal 1a8 in the same DL subframe 1 will be described. To do. In the Nth DL subframe 1a, the DL subframe generation unit 207 arranges the extended DL control signal 1a8 corresponding to the DL data in the extended control signal region 1a7 based on the determination of the control signal region determination unit 2031. At this time, based on the determination (same transmission) of the subframe determination unit 2032, the DL subframe generation unit 207 arranges the extended DL control signal 1a8 in the DL subframe 1 according to the extended DL control signal arrangement rule in the case of the transmission. To do. In the first embodiment, the extended DL control signal 18 is arranged so that the extended DL control signal 18 is placed within the first slot 11 in the extended control signal area 17 of the DL subframe 1. It becomes. Therefore, the DL subframe generation unit 207 arranges the extended DL control signal 1a8 so as to be within the first slot 1a1 in the extended control signal region 1a7 in the Nth DL subframe 1a.

  When the subframe determining unit 2032 determines that the transmission is the same, the DL subframe generating unit 207 further transmits the DL data signal 1a6 corresponding to the extended DL control signal 1a8 previously arranged in the Nth DL subframe 1a to the resource determining unit. Arrange based on 2033 decision. Thereby, the Nth DL subframe 1a includes the DL data signal 1a6 and the extended DL control signal 1a8 corresponding to the DL data signal 1a6.

  On the other hand, the processing of the DL subframe generation unit 207 when the subframe determination unit 2032 determines to transmit (separately send) the DL data signal 16 and the corresponding extended DL control signal 1a8 in different DL subframes 1 will be described. . In the Nth DL subframe 1a, the DL subframe generation unit 207 arranges the extended DL control signal 1a8 corresponding to the DL data in the extended control signal region 1a7 based on the determination of the control signal region determination unit 2031. At this time, based on the determination (separate transmission) of the subframe determination unit 2032, the DL subframe generation unit 207 transfers the extended DL control signal 1a8 to the Nth DL subframe 1a according to the extended DL control signal arrangement rule in the case of the same transmission. Deploy. In the first embodiment, arranging the extended DL control signal 18 so as to be within the second slot 12 in the extended control signal area 17 of the DL subframe 1 is a control signal arrangement rule in the case of separate transmission. Based on the determination of the subframe determination unit 2032, the DL subframe generation unit 207 arranges the extended DL control signal 1a8 so as to be within the second slot 1a2 in the extended control signal region 1a7 in the Nth DL subframe 1a. To do.

  When the subframe determining unit 2032 determines that the transmission is separate, the DL subframe generating unit 207 does not arrange DL data corresponding to the extended DL control signal 1a8 arranged in the Nth DL subframe 1a. As a result, the Nth DL subframe 1a does not include DL data but includes an extended DL control signal 1a8 corresponding to the DL data.

  When the subframe determining unit 2032 determines to send separately, the DL subframe generating unit 207 further transmits the DL data signal 1b6 corresponding to the extended DL control signal 1a8 previously arranged in the N + 1th DL subframe 1b to the resource determining unit 2033. Place based on the decision. As a result, the (N + 1) th DL subframe 1b includes the DL data signal 1b6 and does not include the extended DL control signal 1a8 corresponding to the DL data signal 1b6.

  When the control signal region determination unit 2031 determines to use the DL control signal 1a5, the subframe determination unit 2032 arranges the DL control signal 1a5 in the control signal region 1a3 in the Nth DL subframe 1a. At the same time, a DL data signal 1a6 corresponding to the DL control signal 1a5 is arranged in the data signal region 1a4.

  The DL subframe generation unit 207 inputs a baseband signal corresponding to the generated DL subframe 1 to the DL radio transmission unit 113. The DL wireless transmission unit 113 up-converts the input baseband signal corresponding to the DL subframe 1 into a wireless signal by frequency conversion or the like, and wirelessly transmits the wireless signal to the wireless terminal 3.

  The UL radio reception unit 209 receives a UL radio signal, down-converts the received radio signal by frequency conversion or the like, converts it to a baseband signal corresponding to the UL subframe, and outputs the baseband signal to the UL subframe analysis unit 210. As an example, the UL radio reception unit 209 receives a UL radio signal including response information (ACK / NACK) for the transmitted DL data signal 16. The UL subframe analysis unit 210 extracts a UL data signal (PUSCH), a UL control signal (PUCCH), and a UL reference signal from the baseband signal corresponding to the UL subframe. At this time, UL subframe analysis section 210 extracts each signal based on UL scheduling information (information equivalent to DCI RB allocation) input from scheduler section 203. Then, the UL subframe analysis unit 210 outputs the UL reference signal to the UL reference signal processing unit 211, outputs the UL control signal to the UL control signal demodulation / decoding unit 212, and outputs the UL data signal to the UL data signal demodulation / decoding unit. To 213.

  The UL reference signal processing unit 211 processes the UL reference signal. Specifically, the UL reference signal processing unit 211 obtains UL channel characteristics based on a demodulation reference signal (DM-RS: Demodulation Reference Signal) among the UL reference signals, and the UL control signal demodulation / decoding unit 212 and the UL. The data is input to the data signal demodulator / decoder 213. The UL reference signal processing unit 211 obtains UL reception quality based on a sounding reference signal (SRS) that is a reference signal for scheduling among the UL reference signals, and inputs the UL reception quality to the scheduler unit 203.

  The UL control signal demodulation / decoding unit 212 demodulates and decodes the UL control signal. The UL control signal demodulating / decoding unit 212 demodulates and decodes the UL control signal using the UL channel characteristics input from the UL reference signal processing unit 211, a predetermined modulation scheme, and an error correction coding scheme. The UL control signal demodulation / decoding unit 212 inputs the demodulated / decoded UL control information to the scheduler unit 203. Examples of UL control signals include UL response information (ACK / NACK signals) for DL data, UL scheduling request information, and the like.

  The UL data signal demodulation / decoding unit 213 demodulates the UL data signal and performs error correction decoding. The UL data signal demodulation / decoding unit 213 demodulates and decodes the UL data signal using the UL channel characteristics input from the UL reference signal processing unit 211 and the modulation scheme and error correction coding scheme input from the scheduler unit 203. Do. The UL data signal demodulation / decoding unit 213 inputs the demodulated / decoded UL data information to a UL data processing unit or the like (not shown).

  The transmission network transmission unit 214 communicates data signals and control signals to the other radio base station 2 and other control devices, relay devices, and the like via the backhaul network.

  FIG. 11 is a diagram illustrating an example of a functional configuration of the wireless terminal 3 according to the first embodiment. The radio terminal 3 includes, for example, a DL radio reception unit 301, a DL subframe analysis unit 302, a DL reference signal processing unit 303, a DL control signal demodulation / decoding unit 304, a DL data signal demodulation / decoding unit 305, and a UL control information generation unit. 306, UL control signal encoding / modulating section 307, UL data information generating section 308, UL data signal encoding / modulating section 309, UL reference signal generating section 310, UL subframe generating section 311 and UL radio transmitting section 312. . The DL control signal demodulation / decoding unit 304 includes a DL control information detection unit 3041 and a subframe determination unit 3042.

  The DL radio reception unit 301 receives a DL radio signal, down-converts the received radio signal by frequency conversion or the like, converts it to a baseband signal corresponding to the DL subframe 1, and outputs the baseband signal to the DL subframe analysis unit 302 . The DL subframe analysis unit 302 extracts the control signal region 13, the data signal region 14, the extended control signal region 17, and the DL reference signal from the baseband signal corresponding to the DL subframe 1. Then, the DL subframe analysis unit 302 outputs the DL reference signal to the DL reference signal processing unit 303, outputs the control signal region 13 and the extended control signal region 17 to the DL control signal demodulation / decoding unit 304, and the data signal region 14 Is output to the DL data signal demodulating / decoding unit 305.

  The DL reference signal processing unit 303 processes the DL reference signal. Specifically, the DL reference signal processing unit 303 estimates DL channel characteristics based on the DL reference signal, and the DL channel characteristics are respectively transmitted to the DL control signal demodulation / decoding unit 304 and the DL data signal demodulation / decoding unit 305. Output.

  The DL control signal demodulation / decoding unit 304 extracts DL control information by demodulating and decoding the DL control signal 15 and the extended DL control signal 18 from the control signal region 13 and the extended control signal region 17 of the DL subframe 1.

  DL control information detection section 3041 uses DL channel characteristics, a predetermined demodulation scheme, and error correction decoding scheme to transmit DL control signal 15 and extended DL control signal from control signal area 13 and extended control signal area 17 of DL subframe 1. 18 is demodulated and decoded, and DCI which is DL control information is detected. When detecting the DCI, the DL control information detection unit 3041 recognizes (detects) the DCI addressed to itself based on the decoding result based on the 16-bit CRC scrambled by the RNTI. The DL control information detection unit 3041 recognizes (detects) whether the application target of DCI is UL data (PUSCH) or DL data (PDSCH) based on the DCI format. The DL control information detection unit 3041 inputs the RB allocation and the MCS included in the DCI to the UL subframe generation unit 311 for the DCI addressed to itself for the UL data. When the DL control information detection unit 3041 detects DCI addressed to itself for DL data, the DL control information detection unit 3041 inputs the detected DCI and information regarding the arrangement of the DCI to the subframe determination unit.

  Based on the detected arrangement of DL control information (DCI) addressed to itself, subframe determining section 3042 determines whether DL data signal 1a6 of the same DL subframe 1a is the control target of the DL control information or next DL subframe 1b. It is determined whether the DL data signal is 1b6. When the extended DL control signal 1a8 is arranged in the first slot 1a1 of the extended control signal area 1a7, the subframe determination unit 3042 in the first embodiment controls the extended DL control signal 1a8 to be the same subframe 1a. The data signal 1a6 is determined. That is, it is determined that the extended DL control signal 1a8 and the DL data signal 1a6 that is a control target of the extended DL control signal 1a8 are sent together. On the other hand, when the extended DL control signal 1a8 is arranged in the first slot 1a2 of the extended control signal area 1a7, the subframe determining unit 3042 controls the extended DL control signal 1a8 in the DL in the next subframe 1b. The data signal is determined as 1b6. That is, it is determined that the extended DL control signal 1a8 and the data signal 1b6 to be controlled by the extended DL control signal 1a8 are sent separately. The subframe determination unit 3042 inputs the determination result (same subframe or next subframe) regarding the DCI control target frame, the RB allocation and MCS included in the DCI, to the DL data signal demodulation / decoding unit 305.

  The DL data signal demodulation / decoding unit 305 demodulates the DL data signal 16 from the data signal region 14 of the DL subframe 1 and extracts DL data information by performing error correction decoding. In the data signal area 14 of the DL subframe 1, DL data signals 16 addressed to one or more wireless terminals 3 are multiplexed.

  Here, DL data signal demodulation / decoding section 305 determines DL radio subframe 1 to which RB allocation and MCS are applied, based on the determination result input from subframe determination section 3042. Now, it is assumed that the DCI that is the basis of the input determination result is that received in the Nth DL subframe 1a.

  If the determination result by the subframe determination unit 3042 is “same subframe”, the DL data signal demodulation / decoding unit 305 converts the DL radio subframe to which the input RB allocation and MCS are applied into the same subframe ( The DL data signal 1a6 in the Nth DL subframe 1a) is determined. At this time, the DL data signal demodulation / decoding unit 305 extracts the DL data signal 1a6 from the data signal region 1a4 of the Nth DL subframe 1a input from the DL subframe analysis unit 302 based on the RB allocation, and MCS DL data information is extracted by performing demodulation and decoding based on the above.

  On the other hand, if the determination result by the subframe determination unit 3042 is “next subframe”, the DL data signal demodulation / decoding unit 305 transmits the DL radio subframe 1 to which the input RB allocation and MCS are applied. Is determined as the data signal 1b6 in the next frame (N + 1th DL subframe 1b). At this time, the DL data signal demodulation / decoding unit 305 extracts the DL data signal 1b6 from the data signal region 1b4 of the (N + 1) th DL subframe 1b input from the DL subframe analysis unit 302 based on the RB allocation, and MCS DL data information is extracted by performing demodulation and decoding based on the above.

  The DL data signal demodulation / decoding unit 305 inputs a decoding result indicating whether or not the decoding is successful (whether or not the decoding is performed without error) to the UL control information generation unit 306. This is because response information for DL data is returned to the radio base station 2. The DL data signal demodulation / decoding unit 305 inputs the demodulated / decoded UL data information to a DL data processing unit (not shown).

  The UL control information generation unit 306 generates UL control information and inputs the UL control information to the UL control signal encoding / modulation unit 307. For example, the UL control information generation unit 306 generates ACK information (decoding is successful) or NACK information (decoding is unsuccessful) as response information based on the decoding result input from the DL data signal demodulation / decoding unit 305. . The UL control signal encoding / modulating unit 307 performs error correction encoding / modulation on the UL control information input from the UL control information generating unit 306 based on a predetermined modulation scheme / coding scheme, and an UL subframe generating unit 311 is input.

  The UL data information generation unit 308 generates UL data information and inputs the UL data information to the UL data signal encoding / modulation unit 309. The UL data signal encoding / modulation unit 309 performs error correction encoding / modulation on the input UL data signal 1a6a based on the MCS input from the DL control information detection unit 3041, and inputs the UL data signal 1a6a to the UL subframe generation unit 311. To do.

  The UL reference information generation unit 310 generates UL reference information and inputs it to the UL subframe generation unit 311. As described above, the UL reference signal includes DM-RS (demodulation reference signal) and SRS (sounding reference signal).

  The UL subframe generation unit 311 arranges (maps) the UL data signal, the UL control signal, and the UL reference signal in the UL frame, and generates a UL frame. The UL subframe generation unit 311 performs UL data signal mapping using the RB allocation input from the DL control information detection unit 3041. Also, the UL subframe generation unit 311 maps the UL control signal input from the UL control signal encoding / modulation unit to the UL subframe based on a predetermined rule. For example, for the response signal (the extended DL control signal 1a8 corresponding to ACK information or NACK information) input from the UL control signal encoding / modulating unit, the UL subframe generating unit 311 has DL data corresponding to the response signal. The signal 16 is mapped to the UL subframe four frames after the received DL subframe 1. Further, the UL subframe generation unit 311 maps the UL reference signal to the UL subframe based on a predetermined rule.

  Note that the UL subframe generation unit 311 can determine the UL radio resource when transmitting the response signal in the UL subframe as follows. For example, when UL radio resource allocation information is included in the Nth DL subframe, the UL subframe generation unit 311 can transmit a response signal based on this. Further, when UL radio resource allocation information is not included in the Nth DL subframe, for example, the UL subframe generation unit 311 can use the UL radio resource notified in advance by the control signal of the higher layer. As another example, when UL radio resource allocation information is not included in the Nth DL subframe, the UL subframe generation unit 311 is used to transmit the enhanced DL control signal included in the Nth DL subframe. The UL radio resource can also be determined based on the DL radio resource (can be determined in association with a CCE (Control Channel Element) identification number).

  The UL subframe generation unit 311 inputs a baseband signal corresponding to the generated UL subframe to the wireless transmission unit. The wireless transmission unit 312 up-converts the baseband signal corresponding to the input UL subframe into a wireless signal by frequency conversion or the like, and wirelessly transmits the wireless signal to the wireless base station 2.

According to the first embodiment described above, the decoding delay of the extended DL control signal 1a8 is suppressed by the frame configuration as shown in FIG. 5 as compared with the prior art shown in FIG. First, since the extended DL control signal 1a8a in the first slot 1a1 can be demodulated and decoded before the reception of the first slot 1a1 is completed, the data signal 1a6 in the same subframe can be demodulated and decoded with a relatively small delay. . Further, since the extended DL control signal 1a8b in the second slot 1a2 can be demodulated and decoded before the reception of the second slot 1a2 is completed, the data signal 1b6 in the next subframe can be demodulated and decoded without delay. Therefore, since the delay with respect to the start of demodulation / decoding of the DL data signal 16 is eliminated or suppressed, the above-described retransmission control and buffer problems can be reduced.
[C] Second Embodiment In the first embodiment, whether the control object of the extended DL control signal 18 in the extended control signal area 17 is the same frame or the next frame is arranged in the extended DL control signal 18. It is determined by the slot (slot number). In other words, the boundary line between the two slots in the subframe is a reference line that divides the control target of the extended DL control signal 18. On the other hand, 2nd Embodiment demonstrates the example different from 1st Embodiment about the reference line which divides | segments the control object of the extended DL control signal 18. FIG.

  An example of the frame configuration in the second embodiment will be described based on FIGS.

  FIG. 12 is an example of a frame configuration in which the control target of the extended DL control signal 1a8 is divided based on the reference line 1a9 set at a timing different from the slot boundary on the time axis. The reference line may be set at an arbitrary timing as long as it is within the range of the data signal area 1a4.

  FIG. 13 is an example of a frame configuration in which the control target of the extended DL control signal 1a8 is divided based on the reference line 1a9 set on the frequency axis. This reference line may be set at an arbitrary frequency as long as it is within the range of the data signal region 1a4. Here, particularly in the case of FIG. 13, it is desirable that the size of the DL data signal 1a6 transmitted together with the extended DL control signal 1a8 is smaller. In FIG. 13, there is a possibility that the extended DL control signal 1a8 in the case of transmission is arranged behind the subframe (in the second slot 1a2 or straddling the second slot 1a2), and is the same as the extended DL control signal 1a8. This is because when the size of the DL data signal 1a6 to be transmitted is large, the influence of the delay on the demodulation / decoding start of the DL data signal 1a6 can be large.

  These reference lines 1a9 may be determined in advance, or the radio base station 2 notifies the radio terminal 3 in advance using an upper layer control signal transmitted and received between the radio base station 2 and the radio terminal 3. May be.

  Also in the second embodiment, the same effect can be obtained by the same operation as in the first embodiment.

Since the processing sequence in the second embodiment and the functional configuration of each device follow those of the first embodiment, description thereof will be omitted.
[D] Third Embodiment In the first embodiment or the second embodiment, whether the control object of the extended DL control signal 18 in the extended control signal area 17 is the same frame or the next frame is determined by the extended DL control. This is determined based on the arrangement of the signal 18 in the extended control signal area 17. In contrast, in the third embodiment, the control target of the extended DL control signal 18 in the extended control signal area 17 is the next frame, and the control target of the DL control signal 15 in the control signal area 13 is the same frame. Is. That is, the control target is changed depending on whether the DL control information 15 or the extended DL control information 18 is used.

  An example of a frame configuration in the third embodiment will be described based on FIG. In FIG. 14, two DL control signals 1a5a and 1a5b are arranged in the control signal region 1a3 of the Nth DL subframe 1a. Two extended DL control signals 1a8a and 1a8b are arranged in the extended control signal region 1a7 of the Nth DL subframe 1a. The DL control signals 1a5a and 1a5b are controlled by the data signals 1a6a and 1a6b arranged in the Nth DL subframe 1a, respectively. That is, the DL control signals 1a5a and 1a5b control the DL data signals 1a6a and 1a6b on the same DL subframe 1a as the DL subframe 1a in which the DL control signals 1a5a and 1a5b are arranged, respectively. On the other hand, the extended DL control signals 1a8a and 1a8b are controlled by the data signals 1b6a and 1b6b arranged in the (N + 1) th DL subframe 1b, respectively. That is, the extended DL control signals 1a5a and 1a5b are controlled by the DL data signals 1a6a and 1a6b on the same DL subframe 1a as the DL subframe 1a in which the DL control signals 1a5a and 1a5b are arranged.

  In summary, the DL control signal 1a5 arranged in the control signal area 1a3 is controlled by the data signal 1a6 arranged in the same DL subframe 1a as the DL subframe 1a in which the DL control signal 1a5 is arranged. And On the other hand, the extended DL control signal 1a8 arranged in the extended control signal area 1a7 receives the data signal 1b6 arranged in the DL subframe 1b next to the DL subframe 1a in which the extended DL control signal 1a8 is arranged. Controlled. That is, the control target is changed depending on whether the DL control information 15 or the extended DL control information 18 is used.

  Also in the second embodiment, the same effect can be obtained by the same operation as in the first embodiment.

Since the processing sequence in the third embodiment and the functional configuration of each device are the same as those in the first embodiment, description thereof is omitted.
[E] Fourth Embodiment In the first to third embodiments, whether the control object of the extended DL control signal 18 (including the DL control signal 15 in the third embodiment) is the same frame or the next frame. Is determined based on the arrangement of the extended DL control signal 18 (including the DL control signal 15 in the third embodiment). On the other hand, in the fourth embodiment, the control target of the extended DL control signal 18 is determined based on information on the data size included in the extended DL control signal 18.

  Hereinafter, the processing in the fourth embodiment will be described in comparison with FIGS. 7 and 9.

  The radio base station 2 of the fourth embodiment determines the size of the DL data when determining whether to transmit the DL data together with the extended DL control signal 1a8 or separately (corresponding to S103 in FIG. 7 or S203 in FIG. 9). When the (for example, bit length or byte length) is less than a predetermined value (threshold value), it is sent simultaneously. In other embodiments, any determination criterion for simultaneous transmission or separate transmission can be used, but in the fourth embodiment, it is necessary to determine based on the data size. As the data size, a bit length, a byte length, or the like can be used.

  When transmitting the extended DL control signal 1a8 in the extended control signal area 1a7 of the Nth DL subframe 1a (corresponding to S104 or S204 in FIG. 7), the radio base station 2 of the fourth embodiment is configured to use the extended DL control signal 1a8. May be arranged anywhere in the extended control signal area 1a7.

  However, the extended DL control signal 1a8 of the fourth embodiment includes information on the size of DL data. As the extended DL control signal 1a8 of the fourth embodiment, for example, a signal obtained by encoding and modulating the DL control information (DCI) shown in FIG. 7 can be used. In the DL control information of FIG. 7, RB allocation and MCS correspond to “information on the size of DL data”. Since the resource block size (namely, the number of symbols) is known from the RB allocation, and the modulation scheme (information amount per symbol) is known from the MCS, the DL data size (bit length or byte length) can be obtained based on these. This is because it can.

  When the wireless terminal 3 of the fourth embodiment determines whether the control target of the extended DL control signal 1a8 detected in the extended control signal area 1a7 of the Nth DL subframe 1a is the same subframe or the next subframe (in FIG. 7). (Corresponding to S106 or S206), this determination is made based on the information regarding the size of the DL data included in the extended DL control signal 1a8. For example, the wireless terminal 3 determines the DL data size (bit length or byte) from the RB allocation and the MCS included in the DL control information obtained by demodulating and decoding the extended DL control signal 1a8 detected in the extended control signal area 1a7. Long). When the size of the DL data is less than the predetermined value (threshold value), the wireless terminal 3 determines that the control target of the extended DL control signal 1a8 is the DL data signal 1a6 in the same subframe (Nth DL subframe 1a). To do. On the other hand, when the size of the DL data is equal to or larger than the predetermined value, the wireless terminal 3 determines that the control target of the extended DL control signal 1a8 is the DL data signal 1b6 in the next subframe (N + 1th DL subframe 1b).

  Here, a predetermined value (threshold value) used by the wireless terminal 3 for determination and a predetermined value (threshold value) used when the wireless base station 2 determines whether to transmit DL data together with the extended DL control signal 1a8 or separately. Are the same. For example, the wireless base station 2 may determine the predetermined value in advance and transmit the predetermined value to the wireless terminal 3 using an upper layer control signal or the like. Further, when this predetermined value is 0, that is, when 0 is notified to the terminal as a threshold value, the extended DL control signal 1a8 (E-PDCCH) transmitted / received from the radio base station 2 to the radio terminal 3 is the corresponding DL data. Regardless of the size of the signal 16, the extended DL control signal 1a8 and the DL data signal 16 may be transmitted together (the wireless terminal 3 determines that the transmission is the same). Even when this predetermined value is not set, the extended DL control signal 1a8 (E-PDCCH) transmitted / received from the radio base station 2 to the radio terminal 3 is the extended DL regardless of the size of the corresponding DL data signal 16. The control signal 1a8 and the DL data signal 16 may be transmitted together (the wireless terminal 3 determines that the transmission is performed).

  In addition, as shown in FIG. 15, this embodiment can be applied not only to the extended DL control signal 1a8 in the extended control signal region 1a7 but also to the DL control signal 1a5 in the conventional control signal region 1a3. .

  As described above, according to the fourth embodiment, when the DL data that is the control target of the extended DL control signal 18 in the extended control signal area 17 is large, it is sent separately. As a result, it is possible to start demodulating and decoding large data without delay. On the other hand, DL data with a small size is sent together with the extended DL control signal 18, but even if the start of demodulation / decoding is somewhat delayed, the problems of retransmission control and buffer as described above are small. Therefore, also in 4th Embodiment, the effect similar to 1st Embodiment can be acquired.

The processing sequence in the fourth embodiment and the functional configuration of each device are the same as those in the first embodiment, and thus description thereof is omitted.
[F] Fifth Embodiment As in the fourth embodiment, the fifth embodiment also determines the control target of the extended DL control signal 18 based on information included in the extended DL control signal 18. In the fourth embodiment, information on the data size is used among the information included in the extended DL control signal 18, whereas in the fifth embodiment, the determination is based on information indicating the control target.

  Hereinafter, the processing in the fifth embodiment will be described in comparison with FIGS. 7 and 9.

  When transmitting the extended DL control signal 1a8 in the extended control signal area 1a7 of the Nth DL subframe 1a (corresponding to S104 or S204 in FIG. 7), the radio base station 2 of the fifth embodiment extends the extended DL control signal 1a8. May be arranged anywhere in the extended control signal area 1a7.

  However, the extended DL control signal 1a8 of the fifth embodiment includes information for identifying the control target of the DL control information (for example, information indicating whether the control target is the same frame or the next frame). As the extended DL control signal 1a8 of the fifth embodiment, for example, a signal obtained by encoding and modulating extended DL control information (DCI) as shown in FIG. 16 can be used. In the DL control information of FIG. 16, “control target frame” corresponds to information for identifying the control target of the DL control information. For example, the “control target frame” information can be flag information whose value changes depending on whether the control target is the same frame or the next frame. Further, the “control target frame” information can be a frame identifier (frame serial number) of the frame to be controlled.

  Then, when the radio terminal 3 of the fifth embodiment determines whether the control target of the extended DL control signal 1a8 detected in the extended control signal region 1a7 of the Nth DL subframe 1a is the same subframe or the next subframe (FIG. 7 (corresponding to S106 or S206 of FIG. 7), the determination is performed based on information identifying the control target of the DL control information included in the DL control information obtained by demodulating and decoding the extended DL control signal 1a8.

  As in the fourth embodiment, this embodiment can be applied not only to the extended DL control signal 1a8 in the extended control signal region 1a7 but also to the DL control signal 1a5 in the conventional control signal region 1a3. is there.

  Also in the fifth embodiment, the same effect can be obtained by the same operation as in the first embodiment.

Since the processing sequence in the fifth embodiment and the functional configuration of each device follow those of the first embodiment, description thereof will be omitted.
[G] Sixth Embodiment The sixth embodiment is a modification that can be applied to any of the first to fifth embodiments. The DL subframe in which the extended DL control signal 18 and the DL data signal 16 are different from each other. In the case of transmission at 1 (separate transmission), the resource allocation unit of the DL data signal 16 is made larger than a predetermined value.

  Below, the modification which applied 6th Embodiment to 1st Embodiment is demonstrated. Since this modification has many points in common with the first embodiment, the following description will focus on differences from the first embodiment. As described above, the sixth embodiment can be modified by applying it to any of the second to fifth embodiments, but may be applied in the same manner as for the first embodiment. I will omit the explanation.

  The RB (Resource Block) in the LTE system has been described above, but will be described again here. RB is a unit of radio resources. In the data signal area 14 of the DL subframe 1, 1 RB has a frequency width of, for example, 12 subcarriers. In the LTE system, when the radio base station 2 allocates radio resources to DL data, the minimum unit of frequency component allocation is this RB. However, the radio base station 2 does not always allocate radio resources in units of 1 RB, but allocates radio resources in units of 1 to 4 RBs according to the used frequency bandwidth. For example, when the use frequency bandwidth is 5 MHz, the radio base station 2 allocates radio resources in units of 2 RBs. On the other hand, for example, when the used frequency bandwidth is 10 MHz, the radio base station 2 allocates radio resources in units of 3 RBs. One to four RB groups serving as resource allocation units according to the used frequency bandwidth are referred to as RBG (Resource Block Group), and the number of RBs included in the RBG is referred to as RBG size. In general, the larger the used frequency bandwidth, the same or larger RBG size.

  By the way, in the first embodiment, consider a case where the extended DL control signal 18 and the DL data signal 16 are sent separately. Here, as described above, the DL data signal 16 having a large size can be preferentially sent separately. This is to increase the processing time of data demodulation / decoding until response signal transmission. In this case, the data signal 16 transmitted separately from the extended DL control signal 18 has only a large size.

  Here, if the size of the RBG is increased when there are many data signals 16 having a small size, it is considered that there is a problem in terms of utilization efficiency of radio resources. For example, when all the data is 1 RB or less, assuming that the RBG size is 4 RBs, the DL data signal 16 is allocated only to 25% of the allocated radio resources at most. On the other hand, even if the size of the RBG is increased when there are many large DL data signals 16, it is considered that there are few problems in terms of the utilization efficiency of radio resources. For example, when all the data is 12 RBs or more, even if the RBG size is 4 RBs, the DL data signal 16 is allocated to 75% of the allocated radio resources at least. Therefore, for the DL data signal 16 sent separately, even if the RBG size is increased, it is considered that there are few problems.

  Therefore, the radio base station 2 in the sixth embodiment uses the extended DL control signal 18 sent separately from the DL data signal 16, that is, the extended DL control signal 1a8b arranged in the second slot 1a2 in the Nth DL subframe 1a. The value of RB allocation is set based on a larger RBG size than usual. Also, the radio terminal 3 interprets the value of the RB allocation based on the RBG size larger than normal in the extended DL control signal 1a8b arranged in the second slot 1a2 in the Nth DL subframe 1a, and The data signal 1b6 in the DL subframe 1b is extracted. Here, the RBG size larger than normal may be a predetermined value or may be determined based on the normal RBG size (for example, 1 is added).

  When the used frequency bandwidth is constant, increasing the RBG size can reduce the size of RB allocation (indicating the arrangement of the data signal 16), which is a parameter in DCI. Therefore, when the RBG size is increased, the size of the extended DL control signal 18 can be reduced.

  Therefore, according to the sixth embodiment, in addition to the effect obtained in the first embodiment, there is an effect that the size of the extended DL control signal 18 can be reduced.

Since the processing sequence in the sixth embodiment and the functional configuration of each device follow those of the first embodiment, description thereof will be omitted.
[H] Seventh Embodiment The seventh embodiment is a modification that can be applied to any of the first to sixth embodiments. The DL subframes in which the extended DL control signal 18 and the DL data signal 16 are different from each other are shown in FIG. When transmission is performed at 1 (separate transmission), distributed allocation is applied in resource allocation of the DL data signal 16.

  Below, the modification which applied 7th Embodiment to 1st Embodiment is demonstrated. Since this modification has many points in common with the first embodiment, the following description will focus on differences from the first embodiment. As described above, the seventh embodiment can be modified by applying to any of the second to sixth embodiments, but may be applied similarly to the first embodiment. I will omit the explanation.

  As described above, radio resource allocation in the LTE system is performed in units of RBG size. The RBG size is determined according to the used frequency bandwidth and may be 1 to 4 RBs. For this reason, radio resources may be allocated in units of a plurality (2 to 4) of RBs.

  Here, as an example, consider a case where the RBG size is 4 RBs. At this time, there are two methods when allocating four RBs included in one RBG to radio resources. One is to allocate four RBs so as to be continuous on the frequency axis, which is referred to as local allocation or local transmission. The other is to allocate four RBs so as to be discrete on the frequency axis, which is called distributed allocation or distributed transmission. Two methods are defined as RB allocation algorithms, but details are omitted.

  Meanwhile, scheduling of radio resources is performed in units of subframes on the time axis. The radio base station 2 receives the quality of the DL radio section (CQI: Channel Quality Indicator) for each subband, which is composed of a plurality of consecutive RBs, periodically from each radio terminal 3 or aperiodically in accordance with an instruction from the base station. ) Based on the CQI, the radio base station 2 assigns to each radio terminal 3 as much as possible a frequency (RB) having a good DL radio characteristic quality for each radio terminal 3. Thereby, the utilization efficiency of the radio resource of the whole DL is maximized.

  However, the characteristics of the wireless section of each wireless terminal 3 change with time. In particular, when the wireless terminal 3 is moving at high speed, the change becomes remarkable. In such a case, even if the reception quality of a certain frequency is good in a certain DL subframe 1a, the reception quality of that frequency may deteriorate in the next DL subframe 1b.

  Based on the above description in the LTE system, consider a case where the extended DL control signal 18 and the data signal 16 are sent separately in the first embodiment. In this case, the frequency (RB allocation) to which the data signal 1b6 transmitted in the (N + 1) th DL subframe is allocated is stored in the extended DL control signal 1a8b transmitted in the previous Nth DL subframe 1a. Therefore, when the radio characteristics greatly change between the Nth DL subframe 1a for sending the extended DL control signal 1a8d and the (N + 1) th DL subframe 1b for sending the data signal 1a6a, and the reception quality at the radio terminal 3 side deteriorates, The data signal 1b6 is transmitted using a frequency with poor quality. This is a problem in terms of wireless transmission characteristics. This is because the probability that the wireless terminal 3 successfully decodes the data signal 1b6 decreases and the probability that retransmission occurs will increase, and the possibility that the data transmission throughput will decrease increases.

  In such a case, transmission efficiency may be a particular problem when the above-described local allocation is performed. In general, the reception quality of radio signals is often continuous on the frequency axis. For this reason, in the case of local allocation, it is considered that the reception quality of RBs included in the RBG is likely to deteriorate together. On the other hand, in the case of distributed allocation, it is considered that the reception quality of the RBs included in the RBG deteriorates collectively as compared with the local allocation. Further, in the case of distributed allocation, for example, even if the reception quality of a certain RB included in the RBG deteriorates, the reception quality of another RB may improve, so that the reception quality of the RBG as a whole may be ensured. sell. Normally, when transmitting a data signal in a wireless section, an interleaving process is performed on a bit string to be transmitted, and a deinterleaving process is performed on the receiving side. For this reason, in distributed transmission, even if the reception quality related to a certain RB deteriorates and the signal mapped to that RB is greatly deteriorated in characteristics, the affected bits are decoded by the deinterleaving process on the receiving side. Then it will be diffused. A turbo code used for encoding a data signal is highly resistant to random errors in which erroneous bits are distributed, and thus is compatible with distributed transmission.

  Therefore, the radio base station 2 in the seventh embodiment allocates RBs in the data signal 1b6 transmitted separately from the extended DL control signal 1a8b based on the above-described distributed allocation. Also, the wireless terminal 3 uses the extended DL control signal for the extended DL control signal 1a8b (the extended DL control signal 1a8b arranged in the second slot 1a2 of the Nth DL subframe 1a) that is sent separately from the data signal 1b6. When the DL data signal 1b6 of the (N + 1) th DL subframe 1b is extracted based on the RB allocation that is a parameter of DL control information obtained by demodulating and decoding 1a8b, the distributed allocation is followed.

  According to the seventh embodiment, in addition to the effect obtained in the first embodiment, the effect that it is possible to suppress the deterioration of the transmission characteristics accompanying the change in the radio quality for the data signal 16 transmitted separately from the extended DL control signal 18. Play.

Since the processing sequence in the seventh embodiment and the functional configuration of each device follow those of the first embodiment, description thereof will be omitted.
[I] Eighth Embodiment The eighth embodiment is a modification that can be applied to any of the first to seventh embodiments, and the extended DL control signal 18 in the extended control signal area 17 is controlled. The data signal 16 to be transmitted is modulated by a modulation method such that information to be transmitted is transmitted using not only the phase component of the carrier wave but also the amplitude component, such as 16QAM and 64QAM, and at the next DL subframe 1 When transmission is performed with transmission power lower than normal, information related to transmission power is included in the extended DL control signal 18.

  Below, the modification which applied 8th Embodiment to 1st Embodiment is demonstrated. Since this modification has many points in common with the first embodiment, the following description will focus on differences from the first embodiment. As described above, the eighth embodiment can be modified by applying any of the second embodiment to the seventh embodiment, but it may be applied similarly to the first embodiment. I will omit the explanation.

  In recent years, a so-called heterogeneous network in which a macro cell, which is a normal base station, and a pico cell, which is a small base station (the same applies to a micro cell, a femto cell, and the like) has been studied. Heterogeneous networks are expected to increase the frequency utilization efficiency by efficiently performing traffic offload between macro cells and pico cells.

  In a heterogeneous network, the transmission power of a macro cell is generally larger than the transmission power of a pico cell, and the cell deployment form is such that a pico cell exists in one macro cell. Therefore, inter-cell interference from the macro cell to the pico cell becomes a problem. In order to alleviate this problem, 3GPP Release 10 introduced ABS (Almost Blank Subframe). In the ABS, the macro cell basically transmits only the reference signal without transmitting DL data. The pico cell transmits DL data using the time interval in which the ABS is set in the DL on the macro cell side, whereby interference from the macro cell to the pico cell can be suppressed. However, in the ABS, the macro cell is allowed to transmit DL data with low transmission power. This is because the interference from the macro cell to the pico cell is limited if the transmission power is low. However, in the ABS, the macro cell needs to transmit the DL control signal 15. Here, since the normal control signal region 13 (corresponding to PDCCH) spans the entire transmission frequency band, it is transmitted with low transmission power on the macro cell side even in a time interval in which the macro cell side sets ABS. There is a possibility that interference with the pico cell due to the DL control signal 15 in the control signal area 13 transmitted along with the DL data signal 16 cannot be ignored.

  Therefore, in the ABS, the macro cell may transmit the extended DL control signal 18 (corresponding to E-PDCCH) using only the extended control signal area 17 without using the control signal area 13 (corresponding to PDCCH). It is done. Since the extended control signal area 17 is used only for a part of the frequency within the transmission frequency band, for example, the use restriction of the data transmission area in the ABS section on the macro cell side between the macro cell and the pico cell (the frequency of the used RB, etc.) , It is possible to avoid interference with the DL data signal transmitted in the pico cell due to the enhanced DL control signal 18 (E-PDCCH) transmitted from the macro cell.

  Here, when the extended DL control signal 18 (E-PDCCH) is transmitted in the extended control signal region 17, as described in the location of the problem, the retransmission control or buffer based on the delay with respect to the demodulation / decoding start of the DL data signal 16 is performed. Problem arises. Therefore, even when the extended DL control signal 18 is transmitted in the ABS, it is desirable to solve this problem by any of the above-described embodiments.

  By the way, as described above, when the macro cell transmits DL data in the ABS, it is necessary to reduce the transmission power. Here, if the modulation method of the DL data to be transmitted is a method that does not use an amplitude component for information transmission, such as QPSK, no particular problem occurs due to a change in transmission power between subframes. However, when the modulation method uses an amplitude component for information transmission, for example, 16QAM or 64QAM, there is a possibility that the wireless terminal 3 cannot properly demodulate data due to a change in transmission power. In LTE, information on the transmission power ratio between a resource element used for transmitting a data signal and a resource element used for transmitting a demodulation reference signal is notified to a terminal using a higher layer control signal. This information is introduced assuming application to a normal DL subframe 1 other than ABS. With this information, the terminal can demodulate even if the received DL data signal 16 is modulated by 16QAM, 64QAM, or the like. The power setting value when the macro cell transmits the DL data signal 16 with low power in the ABS section differs depending on where the terminal that receives the DL data signal 16 is located in the macro cell. The setting value may be determined based on an algorithm adopted by a communication company that operates the base station. However, when 16QAM or 64QAM is applied to the DL data signal 16, it is referred to the DL data signal 16 that is effective in the ABS. It is necessary to newly notify the terminal of the signal transmission power ratio. If the effective power ratio in the ABS is also notified to the terminal using a higher layer control signal, dynamic power setting according to the position of each terminal in the micro cell becomes impossible for each ABS.

  Therefore, for example, when the (N + 1) th DL subframe 1b is an ABS, an extended DL control signal 1a8 (corresponding to E-PDCCH) is transmitted using the extended control signal area 1a7 in the Nth DL subframe 1a before the ABS. If the extended DL control signal 1a8 is for the DL data signal 1b6 (PDSCH) of the next frame (that is, ABS), information related to the transmission power of the data signal 1b6 is included in the extended DL control signal 1a8. I will do it. Here, the information related to the transmission power of the data signal 1b6 is, for example, the difference value between the normal DL subframe 1 and the ABS in the transmission power ratio between the demodulation reference signal (DM RS: DeModulation Reference Signal) and the DL data signal 16. be able to. By doing so, the wireless terminal 3 can know the changed transmission power even if the modulation method uses an amplitude component for information transmission such as 16QAM or 64QAM. Therefore, the radio terminal 3 can appropriately demodulate the DL data signal 16.

According to the eighth embodiment, in addition to the effects obtained in the first embodiment, the data signal 16 to be controlled by the extended DL control signal 18 in the extended control signal area 17 includes the phase component of the carrier wave as the information to be transmitted. The radio terminal 3 can demodulate the data signal 16 even when it is modulated by a modulation method that is transmitted using not only the amplitude component but also transmitted with low transmission power in the next subframe. There is an effect.
[J] Other Embodiments In the first to eighth embodiments described above, the DL data signal 16 that is sent separately from the extended DL control signal 18 or the like is transmitted because the extended DL control signal 18 or the like is transmitted. This is the DL subframe 1 next to the DL subframe 1. However, the DL subframe 1 to which the DL data signal 16 is transmitted is not limited to the DL subframe 1 next to the DL subframe 1 to which the extended DL control signal 18 or the like is transmitted.

  For example, the DL subframe 1 to which the DL data signal 16 is transmitted can be the DL subframe 1 after M of the DL subframe 1 to which the extended DL control signal 18 and the like are transmitted (M is a positive integer). . Moreover, you may switch the value of M as needed. For example, M may be increased when the reception quality of the wireless terminal 3 is stable, and M may be decreased when the reception quality varies greatly.

  In the first to eighth embodiments described above, the extended DL control signal 18 and the like and the DL data signal 16 can be transmitted in different DL subframes 1. Therefore, in the first to eighth embodiments, DL transmission is targeted, but the present invention is not limited to this.

  For example, the present invention can be applied to UL transmission. Here, there are two possible modes for applying the present invention to UL transmission. First, the present invention can be applied to UL transmission in a system in which the radio base station 2 determines a data demodulation / decoding method (UL scheduling) of UL transmission, such as LTE. That is, the UL data signal that is the control target of the extended DL control signal 18 in the extended control signal area 17 is transmitted in the UL subframe next to the UL subframe in which the UL data signal is normally transmitted. You can also That is, in LTE, in the UL subframe after four DL subframes 1 in which the extended DL control signal 18 (signal in which DCI is encoded and modulated) used for transmission control of the UL data signal is transmitted, the UL is transmitted. Although the data signal is transmitted, the UL data signal may be transmitted on five or more UL subframes instead of four.

Further, as a second aspect of applying the present invention to UL transmission, the present invention can be applied to UL transmission in a system in which the wireless terminal 3 determines a data demodulation / decoding scheme (UL scheduling) of UL transmission. That is, the extended UL control signal and the like and the UL data signal can be transmitted in different UL subframes.
This aspect is realized by simply exchanging the wireless terminal 3 and the wireless base station 2 in the embodiments described so far. The present invention can also be applied to flat (DL / UL distinction) data transmission such as ad hoc communication.

  Finally, the hardware configuration of each device in the wireless communication system of each of the above embodiments will be described with reference to FIGS. The following example assumes an FDD (Frequency Division Duplex) system, but it goes without saying that it can also be applied to a TDD (Time Division Duplex) system or the like.

  FIG. 17 illustrates an example of a hardware configuration of the radio base station 2 in each of the above embodiments. Each function of the wireless base station 2 described above is realized by a part or all of the following hardware components. The wireless base station 2 in the above embodiment includes a wireless IF (Interface) 21, an analog circuit 22, a digital circuit 23, a processor 24, a memory 25, a transmission network IF 26, and the like.

  The wireless IF 21 is an interface device for performing wireless communication with the wireless terminal 3, and is, for example, an antenna. The analog circuit 22 is a circuit that processes an analog signal, and can be broadly classified into one that performs reception processing, one that performs transmission processing, and one that performs other processing. As the analog circuit 22 that performs reception processing, for example, a low noise amplifier (LNA), a band pass filter (BPF), a mixer, and a low pass filter (LPF). , An automatic gain control amplifier (AGC), an analog / digital converter (ADC), a phase locked loop (PLL), and the like. Examples of the analog circuit 22 that performs transmission processing include a power amplifier (PA), a BPF, a mixer, an LPF, a digital / analog converter (DAC), and a PLL. The analog circuit 22 that performs other processing includes a duplexer. The digital circuit 23 is a circuit that processes a digital signal, and includes, for example, an LSI (Large Scale Integration), an FPGA (Field-Programming Gate Array), an ASIC (Application Specific Integrated Circuit), and the like. The processor 24 is a device that processes data, and includes, for example, a CPU (Central Processing Unit) and a DSP (Digital Signal Processor). The memory 25 is a device that stores data, and includes, for example, a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The transmission network IF 26 is connected to a backhaul network of the wireless communication system via a wired line or a wireless line, and is connected to a transmission network side device including another wireless base station 2 connected to the backhaul network or the core network. An interface device for performing communication.

  A correspondence relationship between the functional configuration and the hardware configuration of the radio base station 2 will be described.

  The DL data information generation unit 201 is realized by, for example, the processor 24, the memory 25, and the digital circuit 23. That is, the processor 24 controls the memory 25 as necessary, and cooperates with the digital circuit 23 as necessary to generate DL data information. The digital circuit 23 may generate DL data information. The DL data signal encoding / modulating unit 202 is realized by the processor 24, the memory 25, and the digital circuit 23, for example. That is, the processor 24 controls the memory 25 as necessary, cooperates with the digital circuit 23 as necessary, and encodes and modulates DL data information to obtain the DL data signal 16. Further, the digital circuit 23 may obtain the DL data signal 16 by encoding and modulating the DL data information.

  The scheduler unit 203 is realized by the processor 24, the memory 25, and the digital circuit 23, for example. That is, the processor 24 controls the memory 25 as necessary, cooperates with the digital circuit 23 as necessary, performs scheduling of radio resources used for radio communication, and performs various controls associated with radio resource scheduling. Do. Further, the digital circuit 23 may perform scheduling of radio resources used for radio communication and various controls associated with the scheduling of radio resources. The control signal area determining unit 2031 is realized by the processor 24, the memory 25, and the digital circuit 23, for example. That is, the processor 24 controls the memory 25 as necessary, cooperates with the digital circuit 23 as necessary, and arranges the DL control signal 15 used for DL data transmission in the control signal area 13 or the extended DL. Whether to arrange the control signal 18 in the extended control signal area 17 is determined. Further, the digital circuit 23 may determine whether to arrange the DL control signal 15 used for transmitting DL data in the control signal area 13 or to arrange the extended DL control signal 18 in the extended control signal area 17. The subframe determination unit 2032 is realized by the processor 24, the memory 25, and the digital circuit 23, for example. In other words, the processor 24 controls the memory 25 as necessary, cooperates with the digital circuit 23 as necessary, and transmits the DL subframe 1 for transmitting the DL data signal 16 to the same DL subframe as the extended DL control signal 18. 1 (same transmission) or the next DL subframe 1 of the extended DL control signal 18 (separate transmission) is determined. Also, the digital circuit 23 sets the DL subframe 1 for transmitting the DL data signal 16 as the same DL subframe 1 as the extended DL control signal 18 (same transmission), or the next DL subframe 1 of the extended DL control signal 18. (Separate delivery) may be determined. The resource determination unit 2033 is realized by the processor 24, the memory 25, and the digital circuit 23, for example. That is, the processor 24 controls the memory 25 as necessary, cooperates with the digital circuit 23 as necessary, and determines a DL radio resource for transmitting DL data to the radio terminal 3. DL radio resources for transmitting DL data to the radio terminal 3 may be determined.

The DL control information generation unit 204 is realized by, for example, the processor 24, the memory 25, and the digital circuit 23. That is, the processor 24 controls the memory 25 as necessary, and cooperates with the digital circuit 23 as necessary to generate DL control information. Further, the digital circuit 23 may generate DL control information. The DL control signal encoding / modulating unit 205 is realized by the processor 24, the memory 25, and the digital circuit 23, for example. That is, the processor 24 controls the memory 25 as necessary, cooperates with the digital circuit 23 as necessary, and encodes and modulates DL control information to generate the extended DL control signal 18. Further, the digital circuit 23 may generate the extended DL control signal 18 by encoding and modulating the DL control information.
The DL reference signal generation unit 206 is realized by the processor 24, the memory 25, and the digital circuit 23, for example. That is, the processor 24 controls the memory 25 as necessary, and generates a DL reference signal in cooperation with the digital circuit 23 as necessary. Further, the digital circuit 23 may generate a DL reference signal. The DL subframe generation unit 207 is realized by, for example, the processor 24, the memory 25, and the digital circuit 23. That is, the processor 24 controls the memory 25 as necessary, cooperates with the digital circuit 23 as necessary, and encodes and modulates the DL data signal 16, the extended DL control signal 18 or the DL control signal 15, and A DL reference signal is arranged in DL subframe 1, and DL subframe 1 is generated. Also, the digital circuit 23 arranges the DL data signal 16 after encoding and modulation, the extended DL control signal 18 or the DL control signal 15, and the DL reference signal in the DL subframe 1 to generate the DL subframe 1 Also good.

  The DL wireless transmission unit 208 is realized by, for example, the wireless IF 21 and the analog circuit 22 (which performs transmission processing). That is, the analog circuit 22 up-converts the input baseband signal corresponding to the DL subframe 1 into a radio signal by frequency conversion or the like, and the radio IF 21 transmits the radio signal to the radio terminal 3 by radio. The UL wireless reception unit 209 is realized by, for example, a wireless IF 21 and an analog circuit 22 (which performs reception processing). That is, the wireless IF 21 receives a UL wireless signal from the wireless terminal 3, and the analog circuit 22 down-converts the received wireless signal by frequency conversion or the like to convert it into a baseband signal corresponding to the UL subframe. The DL radio transmission unit 208 and the UL radio reception unit 209 may be realized by different radio IFs 21 (antennas), but one radio IF 21 may be shared by using a duplexer that is the analog circuit 22. .

  The UL subframe analysis unit 210 is realized by, for example, the processor 24, the memory 25, and the digital circuit 23. That is, the processor 24 controls the memory 25 as necessary, cooperates with the digital circuit 23 as necessary, and generates the UL data signal, the UL control signal, and the UL reference signal from the baseband signal corresponding to the UL subframe. Extract. The digital circuit 23 may extract the UL data signal, the UL control signal, and the UL reference signal from the baseband signal corresponding to the UL subframe. The UL reference signal processing unit 211 is realized by, for example, the processor 24, the memory 25, and the digital circuit 23. That is, the processor 24 controls the memory 25 as necessary, and cooperates with the digital circuit 23 as necessary to process the UL reference signal. The digital circuit 23 may process the UL reference signal. The UL control signal demodulation / decoding unit 212 is realized by, for example, the processor 24, the memory 25, and the digital circuit 23. That is, the processor 24 controls the memory 25 as necessary, cooperates with the digital circuit 23 as necessary, demodulates the UL control signal, and performs error correction decoding. Further, the digital circuit 23 and the UL control signal demodulation / decoding unit 212 may demodulate the UL control signal and perform error correction decoding. The UL data signal demodulating / decoding unit 213 is realized by, for example, the processor 24, the memory 25, and the digital circuit 23. That is, the processor 24 controls the memory 25 as necessary and cooperates with the digital circuit 23 as necessary to demodulate and decode the UL data signal. The digital circuit 23 demodulates and decodes the UL data signal. May be.

  The transmission network communication unit 214 is realized by, for example, the transmission network IF 26, the analog circuit 22, the processor 24, the memory 25, and the digital circuit 23. That is, the processor 24 controls the memory 25 as necessary and cooperates with the digital circuit 23 as necessary to convert a data signal and a control signal to be transmitted into a digital baseband signal. The analog circuit 22 converts the digital baseband signal into a wired signal or a wireless signal, and the transmission network IF 26 transmits the wired signal or the wireless signal. The transmission network IF 26 receives a wired signal or a wireless signal, and the analog circuit 22 converts the wired signal or the wireless signal into a digital baseband signal. In addition, the processor 24 controls the memory 25 as necessary and cooperates with the digital circuit 23 as necessary to convert the digital baseband signal into a data signal or a control signal.

  FIG. 18 illustrates an example of a hardware configuration of the wireless terminal 3 in each of the above embodiments. Each function of the wireless terminal 3 described above is realized by a part or all of the following hardware components. The wireless terminal 3 in the embodiment includes a wireless IF 31, an analog circuit 32, a digital circuit 33, a processor 34, a memory 35, an input IF 36, an output IF 37, and the like.

  The wireless IF 31 is an interface device for performing wireless communication with the wireless base station 2 and is, for example, an antenna. The analog circuit 32 is a circuit that processes an analog signal, and can be broadly classified into one that performs reception processing, one that performs transmission processing, and one that performs other processing. The analog circuit 32 that performs reception processing includes, for example, LNA, BPF, mixer, LPF, AGC, ADC, PLL, and the like. The analog circuit 32 that performs transmission processing includes, for example, PA, BPF, mixer, LPF, DAC, PLL, and the like. The analog circuit 32 that performs other processing includes a duplexer and the like. The digital circuit 33 includes, for example, an LSI, FPGA, ASIC, or the like. The processor 34 is a device that processes data, and includes, for example, a CPU and a DSP. The memory 35 is a device that stores data, and includes, for example, a ROM, a RAM, and the like. The input IF 36 is a device that performs input, and includes, for example, an operation button, a microphone, and the like. The output IF 37 is a device that performs output, and includes, for example, a display, a speaker, and the like.

  A correspondence relationship between the functional configuration and the hardware configuration of the wireless terminal 3 will be described.

  The DL wireless reception unit 301 is realized by, for example, a wireless IF 31 and an analog circuit 32 (which performs reception processing). That is, the radio IF 31 receives a DL radio signal from the radio base station 2, and the analog circuit 32 down-converts the received radio signal by frequency conversion or the like to convert it into a baseband signal corresponding to the DL subframe.

  The DL subframe analysis unit 302 is realized by, for example, the processor 34, the memory 35, and the digital circuit 33. That is, the processor 34 controls the memory 35 as necessary, cooperates with the digital circuit 33 as necessary, and expands the data signal area 14, the control signal area 13, and the extended control from the baseband signal corresponding to the DL subframe 1. The signal area 17 and the DL reference signal are extracted. The digital circuit 33 may extract the data signal area 14, the control signal area 13, the extended control signal area 17, and the DL reference signal from the baseband signal corresponding to the DL subframe 1. The DL reference signal processing unit 303 is realized by, for example, the processor 34, the memory 35, and the digital circuit 33. That is, the processor 34 controls the memory 35 as necessary, and cooperates with the digital circuit 33 as necessary to process the DL reference signal. The digital circuit 33 may process the DL reference signal.

  The DL control signal demodulation / decoding unit 304 is realized by the processor 34, the memory 35, and the digital circuit 33, for example. That is, the processor 34 controls the memory 35 as necessary, cooperates with the digital circuit 33 as necessary, and transmits the DL control signal 15 or the extended DL from the control signal area 13 and the extended control signal area 17 of the DL subframe 1. DL control information is extracted by demodulating the control signal 18 and performing error correction decoding. Further, the digital circuit 33 demodulates the DL control signal 15 or the extended DL control signal 18 from the control signal region 13 and the extended control signal region 17 of the DL subframe 1 and extracts DL control information by performing error correction decoding. May be. The DL control information detection unit 3041 is realized by, for example, the processor 34, the memory 35, and the digital circuit 33. That is, the processor 34 controls the memory 35 as necessary, and cooperates with the digital circuit 33 as necessary to detect DCI as DL control information. Further, the digital circuit 33 may detect DCI that is DL control information. The subframe determination unit 3042 is realized by the processor 34, the memory 35, and the digital circuit 33, for example. That is, the processor 34 controls the memory 35 as necessary, cooperates with the digital circuit 33 as necessary, and based on the detected arrangement of the DCI addressed to itself, the DL sub-control target of the same DL control information is the same. It is determined whether it is the DL data signal 16 of frame 1 or the DL data signal 16 of the next DL subframe 1. Further, based on the detected arrangement of DCI addressed to itself, the digital circuit 33 controls whether the DL control information is the DL data signal 16 of the same DL subframe 1 or the DL data signal 16 of the next DL subframe 1. You may determine whether it is. The DL data signal demodulation / decoding unit 305 is realized by, for example, the processor 34, the memory 35, and the digital circuit 33. That is, the processor 34 controls the memory 35 as necessary, cooperates with the digital circuit 33 as necessary, demodulates the DL data signal 16 from the data signal area 14 of the DL subframe 1, and performs error correction decoding. Thus, DL data information is extracted. Further, the digital circuit 33 may extract the DL data information by demodulating the DL data signal 16 from the data signal area 14 of the DL subframe 1 and performing error correction decoding.

  The UL control information generation unit 306 is realized by the processor 34, the memory 35, and the digital circuit 33, for example. That is, the processor 34 controls the memory 35 as necessary, and cooperates with the digital circuit 33 as necessary to generate UL control information. The digital circuit 33 may generate UL control information. The UL control signal encoding / modulating unit 307 is realized by, for example, the processor 34, the memory 35, and the digital circuit 33. That is, the processor 34 controls the memory 35 as necessary, cooperates with the digital circuit 33 as necessary, and performs error correction coding / modulation of UL control information based on a predetermined modulation scheme / coding scheme. . Further, the digital circuit 33 may perform error correction coding / modulation on the UL control information based on a predetermined modulation method / coding method. The UL data information generation unit 308 is realized by, for example, the processor 34, the memory 35, and the digital circuit 33. That is, the processor 34 controls the memory 35 as necessary, and generates UL data information in cooperation with the digital circuit 33 as necessary. The digital circuit 33 may generate UL data information. The UL data signal encoding / modulating unit 309 is realized by, for example, the processor 34, the memory 35, and the digital circuit 33. That is, the processor 34 controls the memory 35 as necessary, cooperates with the digital circuit 33 as necessary, and encodes and modulates the UL data signal based on MCS. Further, the digital circuit 33 may perform error correction encoding / modulation on the UL data signal based on the MCS. The UL reference signal generation unit 310 is realized by the processor 34, the memory 35, and the digital circuit 33, for example. That is, the processor 34 controls the memory 35 as necessary, and cooperates with the digital circuit 33 as necessary to generate UL reference information. The digital circuit 33 may generate UL reference information. The UL subframe generation unit 311 is realized by, for example, the processor 34, the memory 35, and the digital circuit 33. That is, the processor 34 controls the memory 35 as necessary, cooperates with the digital circuit 33 as necessary, and arranges the UL data signal, the UL control signal, and the UL reference signal in the UL subframe, and the UL subframe. Is generated. Further, the digital circuit 33 may arrange the UL data signal, the UL control signal, and the UL reference signal in the UL subframe to generate the UL subframe.

  The UL wireless transmission unit 312 is realized by, for example, the wireless IF 31 and the analog circuit 32 (which performs transmission processing). That is, the analog circuit 32 up-converts the baseband signal corresponding to the input UL subframe into a radio signal by frequency conversion or the like, and the radio IF 31 radio-transmits the radio signal to the radio base station 2. Note that the UL wireless transmission unit 312 and the DL wireless reception unit 301 may be realized by different wireless IFs 31 (antennas), but one wireless IF 31 may be shared by using a duplexer that is an analog circuit 32. .

1: DL subframe 2: Wireless base station 3: Wireless terminal

Claims (15)

A radio base station transmits a radio signal including a plurality of radio frames in order to a radio terminal, and at least one radio frame of the plurality of radio frames includes data information and control information, and is controlled in the at least one radio frame. An area is arranged and a data area is arranged after the control area, and the data information and another control area can be arranged in parallel along the time axis in the data area, and the control area The control information can be arranged in the other control area, the control information is a wireless communication system including information on the size of the data information,
The radio base station is
An encoding unit that generates encoded data information by encoding the data information corresponding to the control information based on the control information;
When transmitting the wireless signal to the wireless terminal based on the size of the data information, if the size of the data information is less than a threshold, the encoded data information and the encoded data information in a single wireless frame And when the size of the data information is equal to or larger than the threshold, a radio frame before the radio frame including the encoded data information corresponding to the control information is transmitted. An encoded data transmission unit for transmitting the radio signal including the control information in
With
The wireless terminal is
A receiving unit that receives the radio signal including the at least one radio frame including the control information and the encoded data information corresponding to the control information from the radio base station;
An acquisition unit that acquires the size of the data information from information on the size of the data information included in the received control information;
When the size of the acquired data information is less than the threshold, the encoded data information received in the same radio frame as the received control information is decoded, and the size of the acquired data information is the threshold If it is above, a decoding unit that decodes the encoded data received in a radio frame after the radio frame including the received control information;
A wireless communication system comprising: The radio communication system according to claim 1, wherein the control information arranged in the other control area is transmitted and received in an enhanced-physical downlink control channel (E-PDCCH) in Long Term Evolution (LTE). The radio communication system according to claim 1, wherein the plurality of radio frames are a plurality of subframes in Long Term Evolution (LTE). The wireless terminal is
The radio | wireless communications system in any one of Claims 1-3 further provided with the response signal transmission part which transmits the response signal which shows whether decoding of the received said encoded data information was successful within a specific time. Information on the size of the data information included in the control information is
Information indicating the size of resource blocks constituting the radio frame;
Information regarding a modulation scheme when encoding the data information,
The radio | wireless communications system in any one of Claims 1-4 . A radio base station transmits a radio signal including a plurality of radio frames in order to a radio terminal, and at least one radio frame of the plurality of radio frames includes data information and control information, and is controlled in the at least one radio frame. An area is arranged and a data area is arranged after the control area, and the data information and another control area can be arranged in parallel along the time axis in the data area, and the control area The control information can be arranged in the other control area, and the control information is the radio base station in a radio communication system including information on the size of the data information,
An encoding unit that generates encoded data information by encoding the data information corresponding to the control information based on the control information;
When transmitting the wireless signal to the wireless terminal based on the size of the data information, if the size of the data information is less than a threshold, the encoded data information and the encoded data information in a single wireless frame And when the size of the data information is equal to or larger than the threshold, a radio frame before the radio frame including the encoded data information corresponding to the control information is transmitted. An encoded data transmission unit for transmitting the radio signal including the control information in
A wireless base station comprising: The radio base station is
The threshold value to be compared with the size of the data information is transmitted to the wireless terminal using a control signal in a higher layer than the control signal.
The radio base station according to claim 6 . Information on the size of the data information included in the control information is
Information indicating the size of resource blocks constituting the radio frame;
Information regarding a modulation scheme when encoding the data information,
The radio base station according to claim 6 or 7 . A radio base station transmits a radio signal including a plurality of radio frames in order to a radio terminal, and at least one radio frame of the plurality of radio frames includes data information and control information, and is controlled in the at least one radio frame. An area is arranged and a data area is arranged after the control area, and the data information and another control area can be arranged in parallel along the time axis in the data area, and the control area The control information can be arranged in the other control area, and the control information is the radio terminal in the radio communication system including information on the size of the data information,
A receiving unit that receives, from the radio base station, the radio signal including the at least one radio frame that includes the encoded data information obtained by encoding the data information based on the control information and the control information. When,
An acquisition unit that acquires the size of the data information from information on the size of the data information included in the received control information;
When the size of the acquired data information is less than a threshold, the encoded data information received in the same radio frame as the received control information is decoded, and the size of the acquired data information is greater than or equal to the threshold A decoding unit that decodes the encoded data received in a radio frame after the radio frame including the received control information;
A wireless terminal comprising: Information on the size of the data information included in the control information is
Information indicating the size of resource blocks constituting the radio frame;
Information regarding a modulation scheme when encoding the data information,
The wireless terminal according to claim 9 . A radio base station transmits a radio signal including a plurality of radio frames in order to a radio terminal, and at least one radio frame of the plurality of radio frames includes data information and control information, and is controlled in the at least one radio frame. An area is arranged and a data area is arranged after the control area, and the data information and another control area can be arranged in parallel along the time axis in the data area, and the control area The control information can be arranged in the other control area, and the control information is a radio communication method by the radio base station in a radio communication system including information on the size of the data information,
Encoding the data information corresponding to the control information based on the control information to generate encoded data information,
When transmitting the wireless signal to the wireless terminal based on the size of the data information, if the size of the data information is less than a threshold, the encoded data information and the encoded data information in a single wireless frame And when the size of the data information is equal to or larger than the threshold, a radio frame before the radio frame including the encoded data information corresponding to the control information is transmitted. Transmitting the radio signal including the control information in
Wireless communication method. The threshold value to be compared with the size of the data information is transmitted to the wireless terminal using a control signal in a higher layer than the control signal.
The wireless communication method according to claim 11 . Information on the size of the data information included in the control information is
Information indicating the size of resource blocks constituting the radio frame;
Information regarding a modulation scheme when encoding the data information,
The wireless communication method according to claim 11 or 12 . A radio base station transmits a radio signal including a plurality of radio frames in order to a radio terminal, and at least one radio frame of the plurality of radio frames includes data information and control information, and is controlled in the at least one radio frame. An area is arranged and a data area is arranged after the control area, and the data information and another control area can be arranged in parallel along the time axis in the data area, and the control area The control information can be arranged in the other control area, and the control information is a radio communication method by the radio terminal in a radio communication system including information on the size of the data information,
Based on the control information, the radio signal including the at least one radio frame including the encoded data information obtained by encoding the data information corresponding to the control information and the control information is transmitted to the radio base station. Received from the station,
From the information regarding the size of the data information included in the received control information, obtain the size of the data information,
When the size of the acquired data information is less than a threshold, the encoded data information received in the same radio frame as the received control information is decoded, and the size of the acquired data information is greater than or equal to the threshold The encoded data received in a radio frame after the radio frame including the received control information is decoded.
Wireless communication method. Information on the size of the data information included in the control information is
Information indicating the size of resource blocks constituting the radio frame;
Information regarding a modulation scheme when encoding the data information,
The wireless communication method according to claim 14 .