JP2008035288A - Wireless communication apparatus and wireless communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless communication apparatus and a wireless communication method for suppressing degrading of communication quality, even when a mobile terminal at a communication destination moves at a high speed, in wireless communication that uses wireless signals to which pilot symbols and data symbols are allocated. <P>SOLUTION: The wireless communication apparatus receives the wireless signals, wherein the pilot symbols and the data symbols are allocated to wireless resource regions, resulting from dividing the time axis direction into a plurality of symbol intervals from the mobile terminal and executes signal processing of the data symbols, on the basis of the pilot symbols and includes a measurement section for measuring the moving speed of the mobile terminal; a pilot symbol setting section for setting the interval in the time axis direction of the pilot symbols, allocated to the received wireless signals on the basis of the measured moving speed; and a pilot symbol notice section for informing the mobile terminal about the set result of the interval of the pilot symbols. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a radio communication apparatus and a communication method for receiving a radio signal to which a pilot symbol and a data symbol are assigned from a mobile terminal.

  In recent years, various wireless communication systems using an OFDM (Orthogonal Frequency Division Multiplexing) scheme, an OFDMA (Orthogonal Frequency Division Multiple Access) scheme, which is an extension of OFDM, and the like have been proposed (for example, see Patent Document 1).

  In the wireless communication system described above, for example, a wireless base station transmits and receives a wireless signal having a configuration using a wireless signal frame in communication with a mobile terminal. The radio resource area of one radio signal frame is divided into subcarriers (frequency axis) and symbol sections (time axis), and symbols are assigned to the divided radio resource areas. Generally, symbols include a preamble symbol used for symbol synchronization, a data symbol used for transmission of user data, and a pilot symbol. Here, the pilot symbol is “known information” between the radio base station that performs radio communication and the mobile terminal in the radio communication system described above. FIG. 9 shows an example of a symbol configuration assigned in the radio signal frame. As shown in FIG. 9, pilot symbols PL are distributed and allocated among data symbols D in the radio signal frame.

In the wireless communication system described above, when a wireless base station receives a wireless signal from a mobile terminal as a communication destination, data symbol correction processing (equalization) is performed based on pilot symbols assigned to the received wireless signal. Do). Specifically, the radio base station estimates the channel characteristics with the mobile terminal based on the pilot symbols assigned to the received radio signal, and is assigned in the time axis direction and the frequency axis direction of the pilot symbols. Correct the phase distortion of the data symbol. In this way, the radio base station performs a correction process on the data symbols in the time axis direction and the frequency axis direction from the pilot symbols allocated in a distributed manner, so that an environment in which a delayed wave is generated due to multipath or the like. Even below, the communication quality with the mobile terminal is prevented from being deteriorated.
JP 2003-18117 A

  However, for example, when the communication destination mobile terminal moves at high speed, the radio base station changes the magnitude of the delayed wave of the signal received from the mobile terminal in a short period of time, so that the transmission path characteristics with the mobile terminal are also short-term. May change in between. At this time, the radio base station performs data symbol correction processing based on transmission path characteristics that are far from the actual distance because the interval in the time axis direction of pilot symbols arranged in the radio signal frame is too wide. That is, in such a wireless communication system, when the mobile terminal of the communication destination moves at high speed, even if the wireless base station performs the above-described correction processing, the received wireless signal is deteriorated and communication quality is reduced. There was a problem.

  Therefore, the present invention has been made in view of such a situation, and in wireless communication using pilot symbols and data symbols, even when the communication destination mobile terminal moves at high speed, the communication quality is improved. It is an object of the present invention to provide a wireless communication apparatus and a communication method that suppress the decrease.

  In order to solve the problems described above, the present invention has the following features. First, a first feature of the present invention is that a radio signal in which a pilot symbol and a data symbol are assigned to a radio resource region obtained by dividing a time axis direction into a plurality of symbol sections is received from a mobile terminal (mobile terminal 200). And a radio communication apparatus (radio base station 100) that performs signal processing of the data symbol based on the pilot symbol, a measurement unit (measurement unit 105) that measures a moving speed of the mobile terminal, and a measurement A pilot symbol setting unit (pilot symbol setting unit 107) for setting an interval in the time axis direction of the pilot symbol assigned to the radio signal to be received based on the moved moving speed, and an interval of the pilot symbol interval A pilot symbol notification unit (pilot symbol communication unit) that notifies the mobile terminal of the setting result. Part 109) and the subject matter in that it comprises. According to such a feature, for example, when the mobile terminal of the communication destination moves at a high speed and the movement speed increases, the wireless communication apparatus sets the interval of the pilot symbols in the time axis direction to be narrow, for example. Inform the mobile terminal of the result. Then, the radio communication apparatus receives a radio signal assigned with a narrow pilot symbol interval according to the setting result from the mobile terminal. That is, when the mobile terminal moves at a high speed, the radio communication device receives a radio signal to which pilot symbols with a narrow interval in the time axis direction are allocated, and transmits a transmission corresponding to a short-term change based on the pilot symbols. The path characteristic is appropriately calculated, and the data symbol included in the received radio signal is corrected. Therefore, according to the radio communication apparatus, when receiving a radio signal to which a pilot symbol and a data symbol are assigned, even if the communication destination mobile terminal moves at high speed, the communication quality decreases. Can be suppressed.

  Further, for example, when the moving speed of the mobile terminal moves at a low speed, the interval of the pilot symbols in the time axis direction is set with a wide range, for example. That is, the wireless communication apparatus receives a radio signal to which a pilot symbol having a wider interval in the time axis direction than before is received, and based on the pilot symbol, a correction process for a data symbol assigned to the received radio signal I do. Therefore, according to such a wireless communication apparatus, it is possible to reduce the processing load for the calculation of the correction process while maintaining the communication quality with the mobile terminal.

  A second feature of the present invention relates to the first feature of the present invention, wherein the radio signal is composed of a plurality of subcarriers, and the pilot symbol setting unit is configured to transmit all the symbols in the same symbol section. The gist is to assign the pilot symbols to subcarriers. According to such a feature, the radio communication apparatus performs the correction process of the data symbol allocated in the subcarrier direction (frequency axis direction) of the pilot symbol, without performing the correction process of the data symbol allocated in the time axis direction. Since only the correction process needs to be performed, it is possible to reduce the calculation processing load when the correction process is performed.

  A third feature of the present invention relates to the first or second feature of the present invention, wherein the pilot symbol setting unit determines that the moving speed measured by the measuring unit exceeds a predetermined moving speed. The gist of the invention is to narrow the interval in the time axis direction of the pilot symbols assigned to the radio signal to be received.

  According to a fourth aspect of the present invention, a radio signal in which a pilot symbol and a data symbol are assigned to a radio resource region obtained by dividing a time axis direction into a plurality of symbol sections is received from a mobile terminal, and based on the pilot symbol. A communication method in a wireless communication apparatus that performs signal processing of the data symbol, wherein the wireless communication apparatus measures a moving speed of the mobile terminal, and the wireless communication apparatus A setting step of setting an interval in the time axis direction of the pilot symbol assigned to the radio signal to be received based on a moving speed; and the radio communication apparatus sends a setting result of the interval of the pilot symbol to the mobile terminal And a notifying step for notifying to the gist.

  A fifth feature of the present invention relates to the fourth feature of the present invention, wherein the radio signal is composed of a plurality of subcarriers, and the setting step includes all the subcarriers in the same symbol period. The gist of the present invention is to set the allocation of the pilot symbols.

  A sixth feature of the present invention relates to the fourth or fifth feature of the present invention, wherein when the setting step determines that the moving speed measured by the measuring step exceeds a predetermined moving speed, reception is performed. The gist of the invention is to narrow the interval in the time axis direction of the pilot symbols assigned to the radio signal.

  According to the characteristics of the present invention, in a wireless communication system that communicates wireless signals to which pilot symbols and data symbols are assigned, communication quality is reduced even when a communication destination mobile terminal moves at high speed. It is possible to provide a wireless communication device and a communication method for suppressing the above-described problem.

  Next, an embodiment of the present invention will be described. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic.

(Overall schematic configuration of wireless communication system)
FIG. 1 is an overall schematic configuration diagram of a radio communication system according to the present embodiment. The radio communication system according to the present embodiment includes a radio base station 100 (radio communication apparatus) and a mobile terminal 200. In the present embodiment, for example, description of configurations other than the radio base station 100 provided in the radio communication system such as a network and a server is omitted.

The radio base station 100 transmits and receives the downlink radio signal RS _DOWN and the uplink radio signal RS _UP to and from the mobile terminal 200. The downlink radio signal RS _DOWN and the uplink radio signal RS _UP include a control signal for controlling radio communication.

Further, in the present embodiment, wireless communication is performed between the wireless base station 100 and the mobile terminal 200 by the OFDMA method adopted in the standard IEEE 802.16e or the like. Further, the uplink radio signal RS _UP (radio signal) is composed of a radio signal frame (OFDMA frame). Specifically, the uplink radio signal RS _UP is composed of a plurality of subcarriers having different frequency bands, and each subcarrier is assigned a symbol to a radio resource region divided in a time axis direction by a plurality of symbol sections. It has been. Here, as symbols according to the present embodiment, a preamble symbol for executing symbol synchronization between the radio base station 100 and the mobile terminal 200, a data symbol for transmitting user data, a radio base station 100, and the like. A pilot symbol including information known between the mobile terminal 200 and the mobile terminal 200 is assumed.

The mobile terminal 200 transmits and receives the downlink radio signal RS _DOWN and the uplink radio signal RS _UP to and from the radio base station 100. The uplink radio signal RS _UP is composed of the above-described radio signal frame. In the present embodiment, the mobile terminal 200 is assumed to be a mobile device such as a mobile phone, a PDA (Personal Digital Assistant), or a notebook computer.

(Configuration of radio base station)
Next, the configuration of the radio base station 100 will be specifically described. FIG. 2 is a functional block configuration diagram of the radio base station 100. The radio base station 100 includes a radio communication unit 101, a radio signal processing unit 103, a measurement unit 105, a pilot symbol setting unit 107, a pilot symbol notification unit 109, and a baseband processing unit 111.

The radio communication unit 101 transmits the downlink radio signal RS _DOWN to the mobile terminal 200 and receives the uplink radio signal RS _UP transmitted by the mobile terminal 200. The wireless communication unit 101 is connected to the wireless signal processing unit 103 and the measurement unit 105. Further, signal processing such as up-conversion is performed on the signal transmitted from the radio signal processing unit 103, and the downlink radio signal RS _{DOWN is} transmitted. Further, with respect to the uplink radio signal RS _UP received, performs signal processing such as down-conversion, and transmits to the radio signal processing section 103. Radio communication section 101 receives uplink radio signal RS _UP to which pilot symbols and data symbols are assigned from mobile terminal 200.

The wireless signal processing unit 103 is connected to the wireless communication unit 101 and the baseband processing unit 111. The radio signal processing unit 103 performs OFDMA modulation processing such as inverse Fourier transform on the baseband signal transmitted from the baseband processing unit 111 and transmits the radio communication unit 101. Radio signal processing section 103 performs OFDMA demodulation processing such as Fourier transform on the signal from radio communication section 101 and transmits the result to baseband processing section 111. Furthermore, the radio signal processing unit 103 generates a pilot symbol in the own device, a pilot symbol generated, based on the pilot symbols allocated to the uplink radio signal RS _UP received by the wireless communication unit 101, Calculate the transmission path characteristics. The radio signal processing unit 103 performs a data symbol correction process (equalization process) based on the calculated transmission path characteristics. Here, the correction process is a process of correcting the phase fluctuation or the like of the signal waveform of the data symbol based on the transmission path characteristic calculated by the pilot symbol.

Measurement unit 105 is connected to radio communication unit 101 and pilot symbol setting unit 107. The measuring unit 105 according to the present embodiment measures the moving speed V of the mobile terminal 200. Specifically, the measurement unit 105 includes the reference frequency of the uplink radio signal RS _UP stored in advance in the character apparatus, the Doppler frequency of the uplink radio signal RS _UP from the mobile terminal 200 received by the radio signal processing unit 103, and Based on the above, the moving speed V of the mobile terminal 200 is measured. In addition, when the mobile terminal 200 has a position information detection function using GPS or the like and notifies the radio base station 100 of the position information, the measurement unit 105 moves the moving speed of the mobile terminal 200 based on the notified position information. It may be configured to measure V.

Pilot symbol setting section 107 is connected to measurement section 105 and pilot symbol notification section 109. Also, pilot symbol setting section 107 according to the present embodiment sets a time interval in the time axis direction of pilot symbols assigned to received uplink radio signal RS _UP based on moving speed V measured by measuring section 105. When pilot symbol setting section 107 determines that moving speed V measured by measuring section 105 exceeds a predetermined moving speed, pilot symbol setting section 107 narrows the interval in the time axis direction of pilot symbols assigned to received uplink radio signal RS _UP. To do.

  Specifically, the pilot symbol setting unit 107 includes thresholds α to β indicating a predetermined moving speed, and allocation patterns S1 to S3 indicating symbol configurations of three types of radio signal frames having different pilot symbol intervals in the time axis direction. Is stored in advance. Here, in the above-described threshold values α to β, the threshold value β is larger than the threshold value α. Also, in the allocation patterns S1 to S3, the allocation pattern S2 is arranged such that the interval of pilot symbols in the time axis direction (number of symbol intervals) is wider than that of the allocation pattern S1, and the pilot symbol of the allocation pattern S3 is higher than that of the allocation pattern S3. The intervals in the time axis direction are narrowly arranged.

  3 to 5 show symbol configurations of a preamble symbol P, a pilot symbol PL, and a data symbol D that are allocated in a radio signal frame in the allocation patterns S1 to S3 according to the present embodiment. As shown in FIG. 3, in the allocation pattern S1, pilot symbols PL are arranged at intervals of the number “2” of symbol intervals in the time axis direction. Also, as shown in FIG. 4, in the allocation pattern S2, pilot symbols PL are arranged at intervals of every “3” symbol sections in the time axis direction. Also, as shown in FIG. 5, in the allocation pattern S3, the pilot symbols PL are arranged at intervals of every “4” symbol sections in the time axis direction. Note that the pilot symbol interval (number of symbol intervals) in the time axis direction in the allocation patterns S1 to S3 described above is an example, and is not limited to the above-described interval. In the present embodiment, pilot symbol setting section 107 sets pilot symbol allocation to all subcarriers in the same symbol period, as shown in allocation patterns S1 to S3 in FIGS.

  Pilot symbol setting section 107 also stores assignment patterns S1 to S3 that are currently used in wireless communication with mobile terminal 200. Then, the pilot symbol setting unit 107 selects the allocation pattern S1 when the moving speed V measured by the measuring unit 105 is “V> β” which is higher than the threshold value β. In addition, when the threshold value α is exceeded and the threshold value β is equal to or less than “α <V ≦ β”, the allocation pattern S2 is selected. If the threshold α is equal to or less than “V ≦ α”, the allocation pattern S3 is selected. The pilot symbol setting unit 107 also assigns allocation patterns S1 to S3 (for example, allocation pattern S1) currently used in wireless communication with the mobile terminal 200 and selected allocation patterns S1 to S3 (for example, allocation pattern S2). ) And the pilot symbols and the data symbols to be assigned to the radio signal are set to be assigned by the selected assignment patterns S1 to S3 (for example, assignment pattern S2). In this way, the allocation patterns S1 to S3 (for example, the allocation pattern S2) set by the pilot symbol setting unit 107 become the setting results. The pilot symbol setting unit 107 stores the set allocation patterns S1 to S3 and notifies the set allocation patterns S1 to S3 to the pilot symbol notification unit 109. Pilot symbol setting section 107 may be configured not to notify pilot symbol notification section 109 when the compared allocation patterns S1 to S3 are the same. In this embodiment, the pilot symbol setting unit 107 is described as an example in which two threshold values α to β and three allocation patterns S1 to S3 are stored. However, the number of threshold values and the number of allocation patterns are described. Is not limited to this.

Pilot symbol notification section 109 is connected to radio signal processing section 103 and pilot symbol setting section 107. Pilot symbol notifying section 109 notifies mobile terminal 200 of the result of setting the interval of pilot symbols PL set by pilot symbol setting section 107. Specifically, pilot symbol notifying section 109 notifies allocation patterns S1 to S3 set by pilot symbol setting section 107 to mobile terminal 200 via radio signal processing section 103 and radio communication section 101. Pilot symbol notifying section 109 notifies allocation patterns S1 to S3 to mobile terminal 200 using a control signal of downlink radio signal RS _DOWN .

  The baseband processing unit 111 is connected to the wireless signal processing unit 103. In addition, the baseband processing unit 111 executes baseband signal processing.

(Configuration of mobile terminal)
Next, the configuration of the mobile terminal 200 will be described. FIG. 6 is a functional block configuration diagram of the mobile terminal 200. As shown in FIG. 6, mobile terminal 200 includes radio communication section 201, radio signal processing section 203, pilot symbol setting reception section 205, pilot symbol control section 207, and baseband processing section 209.

The wireless communication unit 201 is connected to the wireless signal processing unit 203. Further, the radio communication unit 201 receives the downlink radio signal RS _DOWN from the radio base station 100 and transmits the uplink radio signal RS _UP to the radio base station 100. In addition, signal processing such as up-conversion is performed on the signal transmitted from the radio signal processing unit 203, and the uplink radio signal RS _{UP is} transmitted. Further, the received downlink radio signal RS _{DOWN is} subjected to signal processing such as down conversion and transmitted to the radio signal processing unit 203. The radio communication unit 201 according to the present embodiment transmits an uplink radio signal RS _UP to which a pilot symbol is allocated according to the allocation patterns S1 to S3 according to the allocation patterns S1 to S3 notified from the radio base station 100. Send.

Radio signal processing section 203 is connected to radio communication section 201, pilot symbol setting reception section 205, pilot symbol control section 207, and baseband processing section 209. The radio signal processing unit 203 transmits and receives baseband signals to and from the baseband processing unit 209. The radio signal processing unit 203 performs OFDMA modulation processing such as inverse Fourier transform on the baseband signal, and transmits the radio communication unit 201. Radio signal processing section 203 performs OFDMA demodulation processing such as Fourier transform on the signal from radio communication section 201 and transmits the signal to baseband processing section 209. Radio signal processing section 203 allocates a preamble symbol, a data symbol, and a pilot symbol to the radio signal frame constituting uplink radio signal R _SUP and transmits the radio symbol to radio base station 100 via radio communication section 201. To do. Radio signal processing section 203 executes pilot symbol allocation in accordance with instructions from pilot symbol control section 207 described later.

  Pilot symbol setting receiving section 205 is connected to radio signal processing section 203 and pilot symbol control section 207. When the radio signal processing unit 203 receives a control signal including the allocation patterns S1 to S3 from the radio base station 100, the pilot symbol setting reception unit 205 according to the present embodiment receives the allocation patterns S1 to S1 included in the control signal. S3 is extracted. Pilot symbol setting receiving section 205 notifies pilot symbols control section 207 of the extracted allocation patterns S1 to S3.

Pilot symbol control section 207 is connected to radio signal processing section 203 and pilot symbol setting reception section 205. In addition, the pilot symbol control unit 207 according to the present embodiment, based on the allocation patterns S1 to S3 notified from the radio base station 100, based on the allocation patterns S1 to S3 notified from the pilot symbol setting reception unit 205, It is instructed to allocate pilot symbols to the uplink radio signal RS _UP with the allocation shown in the allocation patterns S1 to S3.

  The baseband processing unit 209 is connected to the wireless signal processing unit 203. In addition, the baseband processing unit 209 executes baseband signal processing.

(Control operation of setting process in wireless base station)
Next, a control operation in which the above-described radio base station 100 sets pilot symbol allocation will be described with reference to the flowchart of FIG.

In step S10, the radio base station 100 receives the uplink radio signal RS _UP transmitted from the mobile terminal 200. At this time, the measuring unit 105 measures the moving speed V of the mobile terminal 200. Specifically, the measurement unit 105 is based on the reference frequency of the uplink radio signal RS _UP stored in advance in its own device and the Doppler frequency of the uplink radio signal RS _UP of the mobile terminal 200 received by the radio signal processing unit 103. Then, the moving speed V of the mobile terminal 200 is measured.

  In step S20, the pilot symbol setting unit 107 of the radio base station 100 determines that the moving speed V measured by the measuring unit 105 is “V ≦ α”, “α <V ≦ β”, and “V ≦ α”. It is determined which one is.

  In step S30A, if the pilot symbol setting unit 107 determines in step S20 that the moving speed V is equal to or less than the threshold value α and “V ≦ α”, the pilot symbol setting unit 107 determines the allocation pattern S1 in which the pilot symbol interval is the symbol interval “2” select.

  In step S30B, if the pilot symbol setting unit 107 determines in step S20 that the moving speed V exceeds the threshold value α and is less than or equal to the threshold value β, “α <V ≦ β”, the interval between pilot symbols is “symbol interval“ The allocation pattern S2 that is 3 ″ is selected.

  In step S30C, if the pilot symbol setting unit 107 determines in step S20 that the moving speed V is “V> β”, which is higher than the threshold value β, the allocation pattern in which the pilot symbol interval is the symbol interval “4”. Select S3.

  In step S40, the pilot symbol setting unit 107 compares the allocation patterns S1 to S3 currently used in radio communication with the mobile terminal 200 with the selected allocation patterns S1 to S3, and determines whether or not each is different. Determine. If it is determined that they are the same, the operation is terminated.

  In step S50, when the pilot symbol setting unit 107 determines that the assignment pattern is different from the currently used assignment patterns S1 to S3, the selected assignment pattern S1 to S3 is set to the selected assignment pattern S1 to S3. The information is stored and notified to the pilot symbol notification unit 109.

  In step S60, in radio base station 100, pilot symbol notification section 109 notifies mobile terminal 200 of allocation patterns S1 to S3 set by pilot symbol setting section 107.

Thereafter, the radio base station 100 receives the uplink radio signal RS _UP to which the pilot symbols are allocated with the set allocation patterns S1 to S3 from the mobile terminal 200 that has notified the allocation patterns S1 to S3. Also, the radio base station 100 performs data symbol correction processing on the uplink radio signal RS _UP based on the pilot symbols assigned to the received uplink radio signal RS _UP . Note that the operations in steps S10 to S60 described above may be performed for each radio signal frame or may be performed every predetermined period (for example, every second).

(Control operation of setting process in mobile terminal)
Next, with reference to the flowchart of FIG. 8, an operation in which the mobile terminal 200 allocates the set pilot symbol will be described.

In step S110, the pilot symbol setting reception unit 205 of the mobile terminal 200 repeats the determination of whether or not the allocation patterns S1 to S3 are included in the control signal of the downlink radio signal RS _DOWN transmitted from the radio base station 100. .

  In step S120, when the pilot symbol setting reception unit 205 determines that the allocation patterns S1 to S3 are included in the control signal, the pilot symbol setting reception unit 205 extracts the allocation patterns S1 to S3 from the control signal and notifies the pilot symbol control unit 207 of them. .

In step S130, pilot symbol control section 207, based on allocation patterns S1 to S3 notified from pilot symbol setting reception section 205, transmits radio signal processing section 203 so that uplink radio signal RS _UP to which pilot symbols are allocated is transmitted. To instruct. In this manner, the mobile terminal 200 transmits an uplink radio signal _{RS UP} shown in the allocation pattern S1 to S3 to the radio base station 100.

(Action / Effect)
According to the radio base station 100 according to the present embodiment described above, in the radio base station 100, the measurement unit 105 measures the moving speed V of the mobile terminal 200 that is the communication destination, and the pilot symbol setting unit 107 moves the movement. According to the speed V, one of the allocation patterns S1 to S3 indicating a symbol configuration having a different interval (number of symbol intervals) in the time axis direction of pilot symbols is selected and set, and the pilot symbol notification unit 109 is set The allocation patterns S1 to S3 (for example, allocation pattern S1) are notified to the mobile terminal 200. Then, the mobile terminal 200 transmits, to the radio base station 100, an uplink radio signal RS _UP to which pilot symbols are allocated according to the notified allocation patterns S1 to S3. That is, for example, when the mobile terminal 200 as a communication destination moves at a high speed (for example, movement speed V> threshold β), the radio base station 100 allocates pilot symbols with a narrow interval in the time axis direction from the mobile terminal 200. The received uplink radio signal RS _UP is received, and based on the pilot symbol, data symbol correction processing is performed on the received uplink radio signal RS _UP . Therefore, according to the radio base station 100, when receiving the uplink radio signal RS _UP to which the pilot symbol and the data symbol are assigned, the mobile terminal 200 as the communication destination moves at a high speed, and the transmission path characteristics become large in a short time. Even in the case of a change, the interval of the pilot symbols in the time axis direction is set to be narrow, and the transmission path identification following the change is calculated, so that the communication quality is prevented from deteriorating.
In this way, according to the radio base station 100, in radio communication using pilot symbols and data symbols, it is possible to suppress a reduction in communication quality even when a communication destination mobile terminal moves at high speed. .

In addition, for example, when the moving speed of the mobile terminal 200 moves at a low speed (for example, moving speed V ≦ threshold α), the radio base station 100 moves the allocation patterns S1 to S3 having a wide interval in the time axis direction of the pilot symbols. The terminal 200 is notified, and the uplink radio signal RS _UP to which the pilot symbols are allocated by the notified allocation patterns S1 to S3 is received from the mobile terminal 200. Therefore, since the number of pilot symbols assigned to the uplink radio signal RS _UP can be reduced, the radio base station 100 can calculate the channel characteristics based on the pilot symbols while maintaining the communication quality with the mobile terminal 200. Can reduce the processing load.

  Also, since the radio base station 100 assigns pilot symbols and data symbols to all subcarriers in the same symbol period in the radio signal, the pilot symbol subcarrier direction (frequency axis) as in the prior art. The correction of the data symbols assigned in the time axis direction only needs to be performed by linear calculation without performing the correction processing of the data symbols assigned to (direction), thus simplifying the calculation and reducing the processing load. it can.

(Other embodiments)
As described above, the contents of the present invention have been disclosed through one embodiment of the present invention. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments will be apparent to those skilled in the art.

  For example, in the above-described embodiment, the radio signal received by the radio base station 100 from the mobile terminal 200 is configured by a plurality of subcarriers, but the radio signal is configured to be transmitted by one carrier. It may be. Specifically, the radio base station 100 has the functions of the measurement unit 105, the pilot symbol setting unit 107, and the pilot symbol notification unit 109 shown in FIG. 2, and uses a single carrier to set a plurality of time axis directions. A radio signal in which a pilot symbol and a data symbol are assigned to a radio resource area divided into symbol intervals is received from the mobile terminal 200, and correction processing for correcting the data symbol signal is executed based on the pilot symbol. It may be configured as follows.

The present invention is also effective when the radio communication unit 101 of the radio base station 100 includes a plurality of antennas and has an adaptive array control function for performing beam forming of radio signals to the mobile terminal 200. Specifically, the wireless communication unit 101, based on the pilot symbols allocated to the uplink radio signal RS _UP, the channel characteristics calculated by the radio signal processing unit 103, calculates the array weight of each antenna, moving You may be comprised so that beam forming may be performed with respect to the downlink radio signal RS _DOWN to the terminal 200. In such a case, the radio base station 100 uses the functions of the measurement unit 105, pilot symbol setting unit 107, and pilot symbol notification unit 109 shown in FIG. By appropriately setting the axial interval, the wireless communication unit 101 can appropriately calculate the transmission path characteristics and the array weights that follow the change, so that beamforming with high followability can be executed.

  In the above-described embodiment, the radio base station 100 is configured to include the measurement unit 105, the pilot symbol setting unit 107, and the pilot symbol notification unit 109. You may comprise in apparatuses other than 100. FIG. For example, these functions can be arranged in the mobile terminal 200. That is, the present invention can be applied to various apparatuses that transmit and receive radio signals to which pilot symbols and data symbols are assigned.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

1 is an overall schematic configuration diagram of a wireless communication system according to an embodiment of the present invention. It is a functional block block diagram of the radio base station which concerns on embodiment of this invention. It is a figure which shows the allocation pattern of the pilot symbol and data symbol in the radio signal frame which concerns on embodiment of this invention. It is a figure which shows the allocation pattern of the pilot symbol and data symbol in the radio signal frame which concerns on embodiment of this invention. It is a figure which shows the allocation pattern of the pilot symbol and data symbol in the radio signal frame which concerns on embodiment of this invention. It is a functional block block diagram of the mobile terminal which concerns on embodiment of this invention. It is a flowchart which shows the operation | movement of the wireless base station which concerns on embodiment of this invention. 3 is a flowchart illustrating an operation of a mobile terminal according to the embodiment of the present invention. It is a figure which shows the arrangement configuration of the pilot symbol and data symbol in the radio signal frame which concerns on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Radio base station, 101 ... Radio communication part, 103 ... Radio signal processing part, 105 ... Measurement part, 107 ... Pilot symbol setting part, 109 ... Pilot symbol notification part, 111 ... Baseband process part, 200 ... Mobile terminal, DESCRIPTION OF SYMBOLS 201 ... Wireless communication part, 203 ... Radio signal processing part, 205 ... Pilot symbol setting receiving part, 207 ... Pilot symbol control part, 209 ... Baseband processing part, (alpha) thru | or (beta) ... Threshold value, D ... Data symbol, P ... Preamble symbol , PL ... pilot symbol, RS _DOWN ... downlink radio signal, RS _UP ... uplink radio signal, S10 to S60 ... step, S110 to S130 ... step, S1 to S3 ... allocation pattern, S30A to S30C ... step, V ... moving speed

Claims (6)

A radio signal in which a pilot symbol and a data symbol are allocated to a radio resource region in which the time axis direction is divided into a plurality of symbol sections is received from a mobile terminal, and signal processing of the data symbol is executed based on the pilot symbol A wireless communication device,
A measuring unit for measuring a moving speed of the mobile terminal;
A pilot symbol setting unit that sets an interval in the time axis direction of the pilot symbol assigned to the radio signal to be received based on the measured moving speed;
A radio communication apparatus comprising: a pilot symbol notification unit that notifies the mobile terminal of a result of setting the pilot symbol interval. The radio signal is composed of a plurality of subcarriers,
The radio communication apparatus according to claim 1, wherein the pilot symbol setting unit sets the assignment of the pilot symbols to all the subcarriers in the same symbol period.     When the pilot symbol setting unit determines that the moving speed measured by the measuring unit exceeds a predetermined moving speed, the pilot symbol setting unit reduces the interval in the time axis direction of the pilot symbol assigned to the received radio signal. The wireless communication apparatus according to claim 1, wherein the wireless communication apparatus is characterized. A radio signal in which a pilot symbol and a data symbol are assigned to a radio resource region obtained by dividing the time axis direction into a plurality of symbol sections is received from a mobile terminal, and signal processing of the data symbol is performed based on the pilot symbol. A communication method in a wireless communication device to perform,
A measuring step for measuring a moving speed of the mobile terminal;
A setting step of setting an interval in the time axis direction of the pilot symbol assigned to the radio signal to be received based on the measured moving speed;
And a notification step of notifying the mobile terminal of a setting result of the pilot symbol interval. The radio signal is composed of a plurality of subcarriers,
5. The communication method according to claim 4, wherein in the setting step, assignment of the pilot symbol is set to all the subcarriers in the same symbol period.   In the setting step, when it is determined that the moving speed measured in the measuring step exceeds a predetermined moving speed, the interval in the time axis direction of the pilot symbol assigned to the radio signal to be received is narrowed. The communication method according to any one of claims 4 and 5.

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