JP2010098580A - Mobile communication system, base station device, mobile station device, and mobile communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To demodulate an uplink signal at a base station device by appropriately processing a signal related to PMI. <P>SOLUTION: A base station device A includes a receiving circuit for receiving a plurality of spatially multiplexed different signals and has a function for notifying a mobile station device B of coefficients weighting the signals. The base station device A notifies the mobile station device B of two or more weight coefficients for weighting signals to be transmitted from the mobile station B to the base station device A while using different channels (403-405) and the mobile station device B, that communicates with the base station device A, selects any one of the weight coefficients received from the base station device A and transmits to the base station device A a first signal representing which one of the transmitted weight coefficients is selected, together with the transmission signals weighted by utilizing the weight coefficients (409). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a base station apparatus, a mobile station apparatus, and a mobile communication method for transmitting and receiving a preprocessing sequence for a system that performs preprocessing on an uplink signal. In this specification, the weighting coefficient is referred to as a precoder.

  As a method for next-generation cellular mobile communication, the international standardization project 3GPP (3rd Generation Partnership Project) has developed W-CDMA (Wideband-Code Division Multiple Access) and GSM (Global System for Mobile). Network specifications are being studied.

  In 3GPP, cellular mobile communication systems have been studied for some time, and the W-CDMA system has been standardized as a third-generation cellular mobile communication system. Also, HSDPA (High-Speed Downlink Packet Access), which further improves the communication speed, has been standardized and the service is operated. Currently, in 3GPP, the evolution of the third generation radio access technology (Long Term Evolution: hereinafter referred to as “LTE”) and LTE Advanced (hereinafter referred to as “LTE-A”) for further higher communication speeds are proposed. Is also being studied.

  In LTE, one frame (10 ms) is one unit divided by time, and one frame is composed of 10 subframes. In downlink transmission from a base station to a mobile station, a downlink control channel (PDCCH: Physical Downlink Channel) and a high-speed downlink shared channel (PDSCH: Physical Downlink Shared Channel) are included in one subframe. The PDCCH is a channel used for transmitting control information from each base station to each mobile station.

  On the other hand, PDSCH is a channel used for transmitting data based on control information transmitted by PDCCH from each base station to each mobile station. In the PDCCH, uplink data transmission-related information, downlink data transmission-related information, and the like are transmitted (each referred to as “uplink grant” and “downlink grant” together as “grant”). A plurality of grants transmitted to the mobile station are interleaved before transmission and included in the PDCCH. The uplink grant includes control information necessary for correctly receiving and demodulating uplink information, such as information on a modulation scheme, a coding rate, and allocated resources. The downlink grant includes information on a modulation scheme, a coding rate, and allocated resources.

  Here, techniques such as AMCS (Adaptive Modulation and Coding Scheme) are being studied in order to determine the modulation scheme and coding rate. Here, AMCS switches MCS (Modulation Coding Scheme: coding rate and data modulation level of error correction) according to the propagation path status of each mobile station apparatus in order to efficiently perform high-speed packet data transmission. It is a method. For example, with regard to data modulation, as the propagation path condition becomes better, switching from QPSK (Quadrature Phase Shift Keying) modulation to multi-value modulation method with higher transmission efficiency such as 16QAM (Quadrature Amplitude Modulation) modulation, 64QAM modulation, etc. Thus, the maximum throughput of the mobile communication system can be increased.

  In LTE-A, in order to significantly increase the communication capacity, application of spatial multiplexing technology using MIMO (Multiple Input Multiple Output) is being considered for the uplink. In spatial multiplexing by MIMO, high-speed signal transmission is realized by spatially multiplexing different information data sequences transmitted from a plurality of transmitters in parallel. Since the receiver receives a plurality of signals, it uses the difference in the radio transmission path to separate it into a plurality of original signal sequences. Here, the effect of increasing the throughput by the spatial multiplexing technology of MIMO greatly depends on the signal separation accuracy.

  As a technical means for improving the signal separation accuracy, it is effective to multiply the transmission signal by a weight according to the propagation path condition (this is called “precoding”). Since the optimum weight depends on the propagation environment and changes depending on the frequency used, in a system that uses different frequencies in the uplink and downlink, the precoder (weighting coefficient) calculated on the receiver side is fed back to the transmitter side. There is a need to. The precoder is information represented by a matrix corresponding to the number of transmission antennas and the number of reception antennas, and it is unrealistic to feed back this as it is from the viewpoint of overhead. On the other hand, it is effective to keep a list of precoders at the transmitter and receiver in advance (this is called “codebook”) and feed back only an index indicating one of these elements. It is. This index is referred to as “PMI (Precoding Matrix Index)”. Here, there are two types of PMI: wideband PMI and subband PMI. The wideband PMI is an effective PMI over all frequencies, and the subband PMI is an effective PMI for each frequency size. The subband PMI can be applied only to a narrower frequency region than the wideband PMI and uses a lot of frequency resources to notify the receiver, but high signal separation accuracy can be obtained. Therefore, in order to improve characteristics while suppressing overhead required for PMI, it is desirable to use one PMI (subband PMI) for each appropriate frequency size.

  On the other hand, in LTE, control signals (uplink grant, downlink grant) are transmitted from the base station apparatus to each mobile station apparatus in order to allocate uplink / downlink resources and to notify information necessary for signal transmission. Is done by doing.

  FIG. 3 is a diagram showing an outline of a flow of processing for searching for a plurality of grant candidates in the PDCCH in one subframe and a grant suitable for the mobile station apparatus from the candidates. As shown in FIG. 3, the subframe (310) transmitted from the base station apparatus to the mobile station apparatus is composed of a PDCCH (311) and a PDSCH (312). In the subframe 310, the horizontal axis indicates time and the vertical axis indicates frequency. Here, the grant is encoded by a convolutional code, and after check bits for error detection (here, CRC: Cyclic Redundancy Check is assumed) are added, all mobile station devices communicating with the base station device And multiplexed in a common PDCCH. Further, the grant is multiplexed on the PDCCH while being interleaved on the PDCCH. After receiving the PDCCH, each mobile station apparatus performs deinterleaving on the PDCCH (315), and can extract the multiplexed grant group (320). The multiplexed grant group 320 is multiplexed with various bit sizes from grant A to grant F. Grants A to F are a group of grants of a plurality of mobile station apparatuses including the own apparatus, but grants A to F are actually distributed.

  Subsequently, grant candidates (eg, 321, 322, 323) addressed to the own device are extracted from the grant group, the error correction-encoded signal sequence is decoded (331), and the decoded signal sequence and the mobile station device As a result of CRC error detection in the ID (333, 335), a grant addressed to the own apparatus is acquired by demodulating without error (337, 341). The mobile station apparatus ID is a unique number in each mobile station apparatus, and can be determined to be a grant addressed to itself when there is no error by using CRC. Here, since the start position of each grant can be specified in advance, the number of detection processes required for grant detection in the grant decoding process is reduced. At this time, if the grant can have various bit sizes, a decoding process is required for each candidate, and the decoding process must be performed for each candidate of the bit size. That is, as the number of grant bit size candidates increases, the receiver load increases for grant detection. Therefore, it is desirable to reduce the number of grant bit size candidates.

  From this point of view, when precoding is applied to uplink MIMO and it is assumed that the PMI is notified to the mobile station apparatus in the uplink grant, if the PMI different for each frequency is included in the uplink grant, the PMI As shown above, the number of demodulation processes when detecting an uplink grant increases, and overhead in the demodulator becomes a problem.

  On the other hand, Non-Patent Document 1 proposes to transmit the control information in the PDSCH instead of the PDCCH for the overhead problem. By extending this and assigning a plurality of PMIs in uplink MIMO, it is conceivable to use PDSCH instead of uplink grant in PDCCH. On the other hand, when a plurality of PMIs are notified using PDSCH, the allocation information of these PMIs is notified by a downlink grant.

  That is, when reporting PMI using PDSCH in uplink MIMO, PMI allocation information and PMI are transmitted separately.

“L1 / L2 Control Channel Structure for E-UTRA Downlink”, 3GPP TSG RAN WG1 LTE_Ad-hoc, R1-060032

  When performing a process related to PMI in uplink MIMO using the method as described above, it is necessary to correctly receive each of the uplink grant, the downlink grant, and the PDSCH. Note that PMI allocation information in the PDSCH is notified by a downlink grant. At this time, the PMI is valid each time, that is, only in the same subframe in which the downlink grant is acquired. If the downlink grant cannot be correctly received, the PMI cannot be acquired regardless of the PDSCH reception state. Further, the uplink grant includes information such as the modulation level and transmission timing of the uplink signal, and if the uplink grant cannot be received correctly, the signal cannot be transmitted regardless of whether or not PMI can be used.

  At this time, even when retransmission processing is performed and uplink grant is acquired, as described above, since PMI is effective only in the same subframe, a signal is transmitted within the same subframe due to a delay in retransmission processing. Cannot be transmitted and PMI cannot be used. That is, (Case 1) When the uplink grant cannot be correctly received and retransmission processing is required for uplink signal transmission, (Case 2) The uplink grant can be correctly received and the downlink grant cannot be correctly received. When PDSCH PMI cannot be acquired, (Case 3) Both uplink grant and downlink grant can be received correctly, and in three cases when PDSCH cannot be received correctly, PMI cannot be used and some measures need to be taken. There is. In these cases, since PMI cannot be used, it becomes impossible to transmit an uplink signal in accordance with an instruction from the base station apparatus, and thus it becomes difficult to detect the uplink signal in the base station apparatus, and the processing procedure corresponding to this is difficult. Definition is required.

  An object of the present invention is to appropriately process a signal related to PMI and to demodulate an uplink signal in a base station apparatus.

  A first technical means for solving the above problem is to notify wideband PMI (PMI applicable to all frequencies) using an uplink grant. If the mobile station apparatus can correctly receive the subband PMI, the mobile station apparatus performs precoding using the subband PMI. On the other hand, when the mobile station apparatus cannot correctly receive the subband PMI, precoding is performed using the wideband PMI. The base station apparatus demodulates the upstream signal assuming either case. Alternatively, information indicating whether the wideband PMI or the subband PMI is used for the uplink signal is transmitted. Information indicating whether the wideband PMI or the subband PMI is used is precoded by the wideband PMI and notified, and the uplink signal is demodulated based on the information.

  The second technical means is to demodulate the uplink signal by assuming both precoding and non-precoding cases. If the mobile station apparatus can correctly receive the subband PMI, the mobile station apparatus performs precoding using the subband PMI. On the other hand, when the mobile station apparatus cannot correctly receive the subband PMI, precoding is not performed. The mobile station apparatus transmits an uplink signal regardless of the presence or absence of precoding. When demodulating, the base station apparatus first demodulates assuming that the subband PMI is used. At this time, if demodulation is not possible correctly, demodulation is performed assuming that the subband PMI is not used. Alternatively, information indicating whether the subband PMI is used is included in the uplink signal and notified. At this time, the base station apparatus can demodulate the uplink signal even when the subband PMI cannot be used based on the information indicating the presence / absence of precoding.

  A third technical means is to perform precoding using the subband PMI used at the immediately preceding transmission timing when the subband PMI cannot be used when precoding the uplink signal. When the mobile station apparatus can correctly receive the subband PMI, the mobile station apparatus uses the subband PMI. On the other hand, when the mobile station apparatus cannot correctly receive the subband PMI, the mobile station apparatus uses the subband PMI used at the immediately preceding transmission timing. When demodulating, the base station apparatus first demodulates the uplink signal assuming that the subband PMI notified at the current transmission timing is used. At this time, if the demodulation is not correctly performed, the uplink signal is demodulated on the assumption that the subband PMI used at the immediately previous transmission timing is used.

  According to the present invention, when a grant and a PMI in MIMO spatial multiplexing for the uplink are transmitted separately, an available precoder is defined, or by canceling the use of the precoder, the mobile station apparatus and the base station It is possible to reduce characteristic degradation due to precoder mismatch between station apparatuses. Furthermore, since the precoder information (information used and information indicating whether or not the precoder is used) transmitted from the mobile station apparatus is transmitted simultaneously with the uplink data, the base station apparatus performs demodulation assuming a plurality of PMI candidates. You can avoid that. It is also possible to reduce the processing of the receiver.

  Hereinafter, a communication technique according to an embodiment of the present invention will be described with reference to the drawings. In the following description, the case where the present invention is embodied as a mobile communication system will be described as an example, but the present invention is not limited to this example. For example, mobile communication methods and the like fall within the scope of the present invention.

(First embodiment)
The mobile communication system according to the first embodiment of the present invention includes a base station device and a mobile station device.

  The mobile communication system according to the first embodiment of the present invention includes a base station apparatus A and a mobile station apparatus B. FIG. 1 and FIG. 2 are functional block diagrams respectively showing configuration examples of a base station apparatus and a mobile station apparatus according to this embodiment. The base station apparatus A illustrated in FIG. 1 includes a transmission unit 110, a scheduling unit 120, a reception unit 130, and an antenna 140. The transmission unit 110 includes a modulation / multiplexing / mapping unit 111 and a wireless transmission unit 112. The scheduling unit 120 includes an uplink scheduling unit 121 and a downlink scheduling unit 122. The downlink scheduling 122 unit includes an MCS control 126 and a downlink grant generation unit 126, and the uplink scheduling unit 121 includes a precoder calculation. Unit 123, MCS control unit 124, and uplink grant generation unit 125. The reception unit 130 includes a radio reception unit 132, an uplink quality calculation unit 133, and a demodulation / data separation unit 131. The operation based on the configuration of the base station apparatus will be described below.

  In the transmission unit 110, the data and control information from the higher layer and the information of the uplink scheduling unit 121 and the downlink scheduling unit 122 are input to the modulation / multiplexing / mapping unit 111 and converted into a signal sequence according to the transmission scheme. Converted. As an example, the input data is provided with modulation and error correction bits according to the MCS specified by the downlink scheduling unit, and is arranged in a data transmission channel including precoder information by the precoder calculation unit 123. The grants generated by the downlink grant generator 127 and the uplink grant generator 125 are arranged in the control channel including other control information. Further, the precoder applied to the uplink signal generated by the precoder calculation unit 123 is multiplexed with the information including data transmitted to all mobile station apparatuses, and is mapped to the signal in accordance with the transmission method. Is done. The output of the modulation / multiplexing / mapping unit 111 is supplied to the wireless transmission unit 112 and converted into a signal sequence that can be transmitted wirelessly, including conversion from a baseband to a carrier frequency. The output of the wireless transmission unit 112 is transmitted to the mobile station device via the antenna 140.

  In the reception unit 130, the radio reception unit 132 receives an uplink signal input via the antenna 140. For the received signal, the uplink quality calculation unit 133 calculates the quality of the uplink signal for each frequency band. The output is input to the uplink scheduling unit 121 and used for precoder calculation and MCS calculation. The output of the wireless reception unit 132 is further input to a demodulation / data separation unit 131, and is divided into control information used for demodulation of an uplink signal and data to be passed to an upper layer. The control information used for the demodulation of the uplink signal is, for example, a precoder applied to the uplink signal. Based on the 123 precoder calculation units in the uplink scheduling unit, 131 demodulation / data separation is referred to. Unit demodulates the uplink signal. Also, assuming that the information related to the precoder applied to the uplink signal is not included, the demodulation / data separation unit 131 demodulates based on the precoder candidate in the precoder calculation unit, or the precoder is not used. Demodulate.

  The uplink scheduling unit 121 collects information necessary for an uplink schedule, performs scheduling, and generates an uplink grant for each mobile station apparatus. Here, it has a function of calculating a precoder from uplink quality information, calculating MCS in that case, and generating an uplink ring associated therewith. The calculated precoder can calculate a different one for each frequency block, and the value is provided to the modulation / multiplexing / mapping unit of the transmission unit 110 together with the downlink grant, and is notified to the mobile station apparatus B.

  The downlink scheduling unit 122 collects information necessary for a downlink schedule, performs scheduling, and generates a downlink grant for each mobile station apparatus. It has a function of calculating MCS and generating a downlink runt associated therewith. A different precoder can be calculated for each frequency block, and the value is provided to the modulation / multiplexing / mapping unit of the transmission unit 110.

  The configuration of mobile station apparatus B is shown below. The mobile station apparatus B illustrated in FIG. 2 includes a transmission unit 210, a scheduling unit 220, a reception unit 230, and an antenna 240. In the reception unit 230, the radio reception unit 232 receives the downlink signal transmitted by the base station apparatus A input via the antenna 240. The output signal of the radio reception unit 232 is input to the demodulation / data separation unit 231 together with the output of the downlink control information management unit 221, and the precoder applied to the uplink grant, downlink grant, and uplink data, and the data signal addressed to the own station To extract. Information of the precoder applied to the uplink grant and the uplink signal is supplied to the uplink control information management unit 222 in the scheduling 220, and the downlink grant is supplied to the downlink control information management unit 221.

  The scheduling unit 220 has a function of managing uplink / downlink signals based on grants. The downlink control information management unit 221 manages the downlink grant transmitted from the base station apparatus, and performs management for correctly receiving the data addressed to the own station transmitted in the schedule described in the downlink grant. . Specifically, the downlink control information management unit 221 includes a downlink grant unit 223, manages the downlink grant transmitted from the base station apparatus, and is transmitted in the schedule described in the downlink grant. A control signal for correctly extracting the signal is provided to the demodulation / data separation unit 231. The uplink control information management unit 222 includes a precoder management / control unit 224, an MCS management / control unit 225, and an uplink grant management unit 226, and manages uplink grants and precoders provided from the demodulation / data separation unit 231. Control information is provided to the modulation unit 211, the precoding unit 212, and the mapping unit 213 so as to perform uplink transmission according to the use of the MCS, precoder, and resource described in the uplink grant.

  The transmission unit 210 includes a modulation unit 211, a precoding unit 212, a mapping unit 213, and a wireless transmission unit 214. Control information and data passed from the upper layer are provided to the modulation unit 211 together with control information provided from the uplink control information management unit 222, and converted into a signal of a modulation scheme designated by the base station apparatus A. The output signal of the modulation unit 211 is input to the precoding unit 212 together with the control information provided by the uplink control information management unit 222, and precoding is performed for each frequency block designated by the base station apparatus A.

  The output signal of the precoding unit 212 is input to the mapping unit 213 together with the uplink control information management unit 222, and mapping is performed according to the instruction of the base station apparatus A. Here, if the precoder cannot be used, the precoding unit 212 passes through without performing precoding, inputs to the mapping unit 213, and performs mapping based on the instruction from the base station apparatus A. For example, when SC-FDMA is used, the transmission signal is arranged in a designated frequency band. The output signal of the mapping unit 213 is provided to the wireless transmission unit 214, converted to a carrier frequency to be used, and necessary frequency filtering, and then transmitted to the base station apparatus A via the antenna 240. On the other hand, the information related to the precoder used is converted into a signal of the modulation scheme designated by the base station apparatus A in the modulation section 211, and precoding designated by the base station is performed in the precoding section 212. After mapping according to the instruction of the base station apparatus A in the mapping unit, it may be included in the uplink signal. Here, the information about the precoder is a signal indicating whether or not the precoder is used and the type of the precoder. When the precoder cannot be used, the precoder information is converted into a modulation scheme signal of the 211 modulation unit, the precoding unit 212 does not perform precoding, and the mapping unit 213 follows the instruction of the base station apparatus A. Perform mapping.

  FIG. 4 is a sequence diagram showing a processing flow between the base station apparatus A and the mobile station apparatus B in the mobile communication system according to the present embodiment, and information included in the uplink grant, the downlink grant, and the PDSCH. FIG.

  A description will be given of the grant notification from the mobile station device B to the base station device A and the precoder notification used for uplink MIMO spatial multiplexing in FIG. 2 and the processing related to the transmission of the uplink signal using this. First, the mobile station apparatus B transmits a reference signal to the base station apparatus A (401), the base station apparatus calculates an uplink propagation path condition from the reference signal, and a precoder (applicable to each frequency block) Notification using subband PMI), and a precoder (notifying using wideband PMI) applied to all frequency blocks is calculated (402).

  Next, the base station apparatus A transmits an uplink grant to the mobile station apparatus B (403). The uplink grant includes the following two pieces of information, which are indicated by reference numeral 412 in FIG. The first of the information is information for demodulating the uplink signal, information that should be commonly recognized by the mobile station apparatus and the base station apparatus, and information on the modulation level, coding rate, In addition to the information for identifying the HARQ retransmission sequence, uplink signal transmission allocation to each mobile station apparatus, transmission timing, precoder usage request, and the like are included (412-1). Here, the usage request for the precoder is a request for the mobile station apparatus to precode the uplink signal using the subband PMI notified from the base station apparatus. The second is wideband PMI (412-2).

  Next, the base station apparatus A transmits a downlink grant to the mobile station apparatus B (404). The downlink grant includes the following two pieces of information, which are shown at 413 in FIG. 4 (b). The first of the information is information for demodulating the PDSCH. In addition to the modulation level, coding rate information, and information for specifying the HARQ retransmission sequence, PDSCH transmission timing, PDSCH transmission allocation (413-1). The second is subband PMI allocation information in PDSCH (413-2).

  Next, the base station apparatus A transmits the PDSCH including the subband PMI to the mobile station apparatus B in accordance with the downlink grant modulation level, coding rate information, PDSCH transmission timing, transmission allocation, etc. Transmit (405). The PDSCH includes the following two pieces of information, which are indicated by reference numeral 414 in FIG. The first of the information is a data signal including upper layer control information (414-1), and the second is a subband PMI (414-2). Here, the subband PMI may be notified directly, or a difference with respect to the already notified subband PMI may be notified. Here, the arrangement of the signal 414 is an example, and an arrangement in which the positional relationship between the data signal and the subband PMI in 414 is reversed or a configuration in which the data and the subband PMI are mixed may be used. , PDSCH may be configured and arranged. Further, the same modulation level and coding rate may be applied to the data signal and the subband PMI, or different modulation levels and coding rates may be applied.

  Next, the mobile station apparatus B that receives the uplink grant notified in 403, the downlink grant notified in 404, and the PDSCH notified in 405 receives the modulation level and the coding rate described in the downlink grant. The subband PMI is extracted from the PDSCH using the information of the above, the transmission timing and transmission allocation of the PDSCH, the allocation information of the subband PMI, and the like (406). Next, after modulating the uplink data based on the modulation level, coding rate information notified by the uplink grant, uplink signal transmission allocation to each mobile station apparatus, transmission timing, etc., extraction is performed according to the uplink ring. The transmitted signal is pre-recorded using the subband PMI (407).

  At this time, if the subband PMI cannot be received correctly, precoding is performed using the precoder notified by the wideband PMI. For example, when an error is detected in the subband PMI, the uplink signal is precoded using the precoder notified by the wideband PMI. On the other hand, in order to notify PMI information (subband PMI or wideband PMI) indicating the precoder used, the PMI information is precoded using the precoder notified by the wideband PMI (408).

  The uplink signal including the PMI information is transmitted to the base station apparatus A based on the resource according to the uplink grant (409). Here, the transmitted uplink signal includes the following two pieces of information, which are indicated by reference numeral 415 in FIG. 4B. The first information is a data signal including upper layer control information (415-1), and the second is PMI information indicating the precoder used (415-2). The arrangement of PMI information in 415 is an example, and in order to obtain the effect of frequency diversity by interleaving, it may be distributed in uplink data signals. Further, the PMI information is notified using, for example, one bit of the uplink signal. As indicated by reference numeral 416 in FIG. 4C, this 1 bit is used when the precoder notified of “0” by the subband PMI is used and the precoder notified of “1” by the wideband PMI. (416). Alternatively, the assignment may be reversed. Further, in order to improve the communication quality, error correction coding may be performed on this 1 bit.

  The base station apparatus A first extracts PMI information from the uplink signal according to the modulation level, coding rate information, uplink signal transmission assignment, transmission timing, and wideband PMI in the uplink grant (410). Next, the uplink data signal is demodulated according to the uplink grant information used to demodulate the PMI information at 410 and the PMI information extracted at 410 (411).

  On the other hand, when PMI information indicating the precoder used by the mobile station apparatus is not included in the uplink signal at 408, the base station apparatus skips without performing 410 extraction processing, and at 411, first, the subband is skipped. An uplink signal is demodulated on the assumption that precoding is performed using a precoder notified by PMI. At this time, if the demodulator cannot correctly demodulate, the uplink signal is demodulated on the assumption that precoding was performed using the precoder notified by the wideband PMI. Here, either the precoder notified by the subband PMI or the precoder notified by the wideband PMI may be assumed and demodulated first. Further, these two kinds of decoding processes may be demodulated in parallel, and the resulting demodulated signal may be used as an uplink data signal.

  Through the above processing, in a situation where the subband PMI allocation information and the subband PMI are transmitted separately, even when the subband PMI cannot be correctly received by notifying the wideband PMI using the uplink grant, The mobile station apparatus B can prevent a situation in which an uplink signal cannot be transmitted by performing precoding using the precoder notified by the wideband PMI.

(Second Embodiment)
FIG. 5 is a sequence diagram showing a processing flow between a base station apparatus and a mobile station apparatus in the mobile communication system according to the present embodiment, and information included in uplink grant, downlink grant, and downlink data. It is a figure which shows the example of a structure. In the time range of the sequence diagram shown in FIG. 5 (a), the uplink data signal communication between the mobile station apparatus B and the base station apparatus A is in the time range shown in the present embodiment. It is assumed that spatial multiplexing by the MIMO / SM system is performed. In the present embodiment, the process (procedure) between the base station apparatus and one mobile station apparatus has been described, but the same process is performed when a plurality of mobile station apparatuses communicate with the base station apparatus. Such processing (means) falls within the scope of the present invention.

  FIG. 5 is a sequence diagram illustrating a flow of processing between the base station apparatus and the mobile station apparatus, and an uplink grant, a downlink grant, and a PDSCH in the mobile communication system according to the present embodiment.

  In the mobile communication system according to the present embodiment, PMI is not notified using an uplink grant, and when the precoder notified by PDSCH is not used, the mobile station apparatus transmits an uplink signal without performing the precoder. Transmission differs from the first embodiment.

  First, the mobile station apparatus B transmits a reference signal to the base station apparatus A (501), and the base station apparatus A calculates an uplink propagation path condition from the reference signal, and an optimum precoder (subband) is obtained for each frequency block. (Notify using PMI) is calculated (502). Next, the base station apparatus A transmits an uplink grant to the mobile station apparatus B (503). The uplink grant is indicated by reference numeral 312 in FIG. 5 (b). As information for demodulating an uplink signal, information on modulation level, coding rate information, and information for specifying a HARQ retransmission sequence is provided. In addition, uplink signal transmission allocation to each mobile station apparatus, transmission timing, precoder usage request, and the like are included.

  Next, the base station apparatus transmits a downlink grant to the mobile station apparatus (504). The downlink grant is indicated at 513 and includes the following two pieces of information. The first is information for demodulating the PDSCH, which includes the modulation level, coding rate information, information for specifying the HARQ retransmission sequence, PDSCH transmission timing, PDSCH transmission allocation, and the like ( 513-1). The second is subband PMI allocation information in PDSCH (513-2).

  Next, the base station apparatus transmits PDSCH to the mobile station apparatus (505). PDSCH is shown by 514 in FIG. 5B and includes the following two pieces of information. The first information is a data signal including upper layer control information (514-1). The second information is subband PMI (514-2). At this time, the subband PMI may notify directly, or may notify the difference with respect to the already notified PMI. Here, the arrangement of the signal 514 is an example, and an arrangement in which the positional relationship between the data signal and PMI in 514 is reversed or a configuration in which data and PMI are mixed may be adopted. Any configuration and arrangement may be used. Further, the same modulation level and coding rate may be applied to the data signal and the subband PMI, or different modulation levels and coding rates may be applied.

  Next, the mobile station apparatus B that has received the uplink grant notified in 503, the downlink grant notified in 504, and the PDSCH notified in 505, uses the information described in the downlink grant from the PDSCH. A subband PMI is extracted (506). Here, when the downlink grant cannot be correctly received, for example, when an error is detected in the downlink grant, the subband PMI cannot be used.

  Next, the mobile station apparatus B modulates the uplink data based on the modulation level notified by the uplink grant, the coding rate information, the transmission assignment of the uplink signal to each mobile station apparatus B, the transmission timing, etc. Thereafter, the transmission signal is precoded using the subband PMI extracted according to the uplink grant (507). On the other hand, for example, when an error is detected by adding a CRC to the subband PMI in advance at 506, precoding is not performed.

  Next, the mobile station apparatus B includes information indicating whether the precoder notified by the subband PMI in 507 is used in part of the uplink data (508). An uplink signal including information indicating whether the precoder is used is transmitted to the base station apparatus A based on resources according to the uplink grant (509). Here, the uplink signal to be transmitted includes the following two pieces of information, which is indicated by 515 in FIG. The first information is a data signal including upper layer control information (515-1), and the second information is information indicating whether the precoder notified by the subband PMI is used ( 515-2). 515 is an example of the arrangement of information indicating the presence / absence of use of the precoder, and may be distributed in order to obtain the effect of frequency diversity by interleaving. Here, the information indicating whether or not the precoder is used is notified using, for example, one bit of the uplink signal. In this 1 bit, “0” indicates that the precoder is used, and “1” indicates that the precoder is not used (516 in FIG. 5C). Alternatively, the assignment may be reversed. Further, error correction coding may be performed on the 1 bit. First, in accordance with the uplink grant, the base station apparatus A extracts information indicating whether or not the precoder is used from the uplink data signal (510). Next, the uplink data is demodulated according to the information indicating the presence or absence of the use of the precoder extracted by the uplink grant or 510 (511).

  If the information indicating whether the mobile station apparatus used the precoder is not included in the uplink data signal at 508, the base station apparatus passes through 510 without performing processing, and at 511, first, precoding is performed. Assuming that the uplink signal is demodulated. At this time, if the demodulation is not correctly performed, the uplink signal is demodulated on the assumption that precoding has not been performed. Here, either the case where precoding is performed or the case where it is not performed may be demodulated by assuming first. Further, these two kinds of decoding processes may be demodulated in parallel, and the resulting demodulated signal may be used as an uplink data signal.

  As described above, even when the subband PMI allocation information and the subband PMI are transmitted separately, even in a situation where the subband PMI cannot be correctly received, the mobile station apparatus does not use the precoding to It is possible to prevent a situation in which transmission is impossible.

(Third embodiment)
FIG. 6 is a sequence diagram (FIG. 6 (a)) showing a processing flow between the base station apparatus A and the mobile station apparatus B in the mobile communication system according to the third embodiment of the present invention, and an uplink. It is the figure (FIG.6 (b)) which showed the information contained in a grant, a downlink grant, and downlink data. In the time range of the sequence diagram shown here, the communication of the uplink data signal between the mobile station apparatus B and the base station apparatus A is the MIMO · SM in the time range shown in the present embodiment. It is assumed that spatial multiplexing by the method is performed. In the present embodiment, the processing (procedure) between the base station apparatus A and one mobile station apparatus B is described as an example, but even when a plurality of mobile station apparatuses communicate with the base station apparatus. It can be implemented by the same processing (means).

  As described above, FIG. 6 is a sequence diagram illustrating the flow of processing between the base station apparatus A and the mobile station apparatus B in the mobile communication system according to the present embodiment, and the uplink grant, the downlink grant, and the PDSCH. FIG. However, in the initial state in FIG. 6, the uplink signal obtained by performing precoding using the precoder notified by the subband PMI notified from the base station device A by the mobile station device B to the base station device A At least once after successful transmission / reception, both the mobile station apparatus B and the base station apparatus A hold the subband PMI used immediately before the current transmission timing.

  The mobile communication system according to the present embodiment does not use the precoder notified by the subband PMI at a certain transmission timing when the subband PMI cannot be used, but uses the subband PMI before the transmission timing. It differs from the first and second embodiments described above in that precoding is performed using the notified precoder. Here, since the transmission process of the precoded uplink signal performed in advance is the same as that of the second embodiment, the description thereof is omitted.

  The processing procedure between the base station apparatus A and the mobile station apparatus B is the same after transmission / reception of the precoded uplink signal. First, a reference signal is transmitted from the mobile station apparatus B to the base station apparatus A (601), the base station apparatus A calculates an uplink propagation path condition from the reference signal, and is applied to each frequency block. (Notify using subband PMI) is calculated (602).

  Next, the base station apparatus A transmits an uplink grant to the mobile station apparatus B (603). The uplink grant is indicated by reference numeral 614 in FIG. 6 (b). As information for demodulating the uplink signal, the uplink level, the coding rate information, and the information for specifying the HARQ retransmission sequence are included. , Uplink signal transmission allocation, transmission timing, precoder usage request, and the like.

  Next, the base station apparatus A transmits a downlink grant to the mobile station apparatus B (604). The downlink grant is indicated by reference numeral 615 in FIG. 6B, and includes the following two pieces of information. The first information is information for demodulating the PDSCH, and includes the modulation level, coding rate information, information for identifying the HARQ retransmission sequence, PDSCH transmission timing, transmission allocation, and the like. (615-1). The second information is PMI allocation information in the PDSCH (615-2).

  Next, the base station apparatus A transmits the PDSCH to the mobile station apparatus in accordance with the downlink grant modulation level, coding rate information, PDSCH transmission timing, transmission allocation, and the like transmitted in 604 (605). PDSCH is indicated by 616 in FIG. 6B and includes the following two pieces of information. The first information is a data signal including upper layer control information (616-1). The second information is subband PMI (616-2). Here, the subband PMI may be notified directly, or a difference with respect to the already notified subband PMI may be notified. Here, the signal arrangement of 616 is an example, and an arrangement in which the positional relationship between the data signal and the subband PMI in 616 is reversed or a configuration in which the data and the subband PMI are mixed may be used. You may comprise and arrange | position in any of PDSCH. Further, the same modulation level and coding rate may be applied to the data signal and the subband PMI, or different modulation levels and coding rates may be applied.

  Next, the mobile station apparatus B that has received the uplink grant notified in 603, the downlink grant notified in 604, and the PDSCH notified in 605 have the modulation level and coding rate described in the downlink grant. The subband PMI is extracted from the PDSCH using information, PDSCH transmission timing and transmission allocation, subband PMI allocation information, and the like (606). Next, the uplink data is modulated based on the modulation level, coding rate information notified by the uplink grant, uplink signal transmission assignment to each mobile station apparatus, transmission timing, etc., and then extracted according to the uplink grant. Pre-recording is performed using the sub-band PMI (607). At this time, if the subband PMI cannot be correctly received, for example, if an error is detected in the downlink grant, the precoder notified by the subband PMI at the current transmission timing cannot be used.

  Next, the mobile station apparatus uses the precoder notified by the subband PMI extracted in 606, information on the modulation level and coding rate notified by the uplink grant, and the uplink signal for each mobile station apparatus B After the uplink data is modulated based on the transmission assignment, transmission timing, etc., precoding is performed using the extracted subband PMI according to the uplink grant (607). At this time, if the subband PMI cannot be received correctly, the precoder notified by the subband PMI at the timing immediately before the current time is used. At this time, if it is determined that the precoder should not be used, the precoder is not used.

  Next, the mobile station apparatus B uses the PMI information indicating the precoder used in 607 (the precoder notified by the subband PMI at the current transmission timing or the precoder notified by the subband PMI at the immediately previous transmission timing, or the precoder Is not included in the uplink signal (608).

  The uplink data signal including the PMI information is transmitted to the base station apparatus based on resources according to the uplink grant (609). Here, the uplink signal to be transmitted includes the following two pieces of information, which is indicated by reference numeral 617 in FIG. The first information is a data signal including upper layer control information (617-1), and the second information is PMI information indicating the precoder used (617-2). The arrangement of PMI information in 617 is an example, and in order to obtain the effect of frequency diversity by interleaving, it may be distributed in uplink data signals. Further, the PMI information is notified using, for example, 2 bits of the uplink data signal. These 2 bits are a subband PMI indicating a precoder using “00” at the current transmission timing (current PMI) and a subband PMI indicating a precoder using “01” at a transmission timing one past from the present. (PMI immediately before) and “11” is not used by the precoder (618 in FIG. 6C). Or bit allocation different from this may be used. Further, in order to improve the communication quality, error correction coding may be performed on these 2 bits. Next, after transmitting the uplink signal, the mobile station apparatus B holds the current precoder and discards the immediately preceding precoder (610). At this time, when the previous precoder is used in the mobile station apparatus B, the previous precoder is held.

  The base station apparatus A first extracts precoder information used from the uplink signal according to the modulation level and coding rate information in the uplink grant, transmission assignment of the uplink signal, and transmission timing (611). Next, the uplink data is demodulated according to the uplink grant information used in 611 and the PMI information extracted in 611 (612). Next, the previous PMI is discarded and the current PMI is held (613). At this time, when the immediately preceding PMI is used in the mobile station apparatus, the immediately preceding PMI is held.

  On the other hand, when the information indicating the subband PMI indicating the precoder used by the mobile station apparatus B is not included in the uplink signal at 608, the base station apparatus A passes without performing the process of 611. First, the uplink signal is demodulated assuming that the precoder notified by the current subband PMI is used. At this time, if the demodulator cannot correctly demodulate, the uplink signal is demodulated assuming that the precoder notified by the immediately preceding subband PMI is used. Further, when the demodulator cannot correctly demodulate, the uplink signal is demodulated assuming that the precoder is not used. Here, when the precoder notified by the current subband PMI is used, when the precoder notified by the immediately preceding subband PMI is used, and when the precoder is not used, which one is assumed is demodulated first. You may do it. Further, these two kinds of decoding processes may be demodulated in parallel, and the resulting demodulated signal may be used as an uplink data signal.

  As described above, in a situation where subband PMI allocation information and subband PMI are transmitted separately, even when the subband PMI cannot be received correctly, the mobile station apparatus is notified by the subband PMI at the immediately previous transmission timing. By using the precoder or not using the precoder, it is possible to prevent a situation in which an uplink signal cannot be transmitted.

  In addition, a program for realizing the functions described in the present embodiment is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed to execute processing of each unit. May be performed. The “computer system” here includes an OS and hardware such as peripheral devices.

  Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used.

  The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time, like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory in a computer system serving as a server or a client in that case is also used to hold a program for a certain period of time. The program may be a program for realizing a part of the above-described functions, or may be a program that can realize the above-described functions in combination with a program already recorded in a computer system.

    The present invention is applicable to a communication device.

It is a functional block diagram which shows the example of 1 structure of the base station apparatus by embodiment of this invention. It is a functional block diagram which shows the example of 1 structure of the mobile station apparatus by embodiment of this invention. It is a figure which shows the outline of the flow of a process which searches the grant suitable for a mobile station apparatus from the some grant candidate in PDCCH in 1 sub-frame, and the candidate. It is the sequence diagram which shows the flow of the process between a base station apparatus and a mobile station apparatus in the mobile communication system by this Embodiment, and the figure which showed the information contained in an uplink grant, a downlink grant, and PDSCH. In the mobile communication system by the 2nd Embodiment of this invention, the sequence diagram which shows the flow of a process between a base station apparatus and a mobile station apparatus, and the information contained in an uplink grant, a downlink grant, and downlink data It is a figure which shows the example of a structure. In the mobile communication system by the 3rd Embodiment of this invention, the sequence diagram (FIG. 6 (a)) which shows the flow of the process between a base station apparatus and a mobile station apparatus, an uplink grant, a downlink grant, It is the figure (FIG.6 (b)) which showed the information contained in downlink data.

Explanation of symbols

DESCRIPTION OF SYMBOLS 110 ... Transmission part, 111 ... Modulation / multiplexing / mapping part, 112 ... Radio transmission part, 120 ... Scheduling part, 121 ... Uplink scheduling part, 122 ... Downlink scheduling part, 126 ... MCS control part, 127 ... Downlink Grant generating section, 130 ... receiving section, 132 ... radio receiving section, 133 ... uplink quality calculating section, 131 ... demodulating / data separating section, 140 ... antenna, 210 ... transmitting section, 211 ... modulating section, 212 ... precoding section 213 ... Mapping unit, 214 ... Radio transmission unit, 222 ... Uplink control information management unit, 224 ... Precoder management / control unit, 225 ... MCS management / control unit, 226 ... Uplink grant management unit, 231 ... Demodulation / data Separation unit, 233 ... downlink grant unit, 240 ... antenna.

Claims (15)

In a base station apparatus having a reception circuit for receiving a plurality of different spatially multiplexed signals and having a function of notifying a mobile station apparatus of a coefficient for weighting the signal,
A base station apparatus, wherein two or more weighting factors for weighting a signal transmitted from the mobile station apparatus to the base station apparatus are notified to the mobile station apparatus using different channels. A mobile station apparatus that communicates with the base station apparatus according to claim 1,
A first one representing which one of the weighting factors received from the base station apparatus is selected, and which one of the weighting factors transmitted is selected together with a transmission signal weighted using the weighting factor. The mobile station apparatus transmits the signal (1) to the base station apparatus.   3. A signal transmitted from the mobile station apparatus according to claim 2 is received, and after extracting the first signal, the transmission signal is demodulated based on the extracted first signal. The base station apparatus described in 1. In a base station apparatus having a reception circuit for receiving a plurality of different spatially multiplexed signals and having a function of notifying a mobile station apparatus of a coefficient for weighting the signal,
Transmitting one or more weighting factors for weighting signals transmitted from the mobile station apparatus to the base station apparatus to the mobile station apparatus;
The base station apparatus, wherein the weighting factor is notified to the mobile station apparatus using a channel different from uplink signal allocation information. A mobile station apparatus that communicates with the base station apparatus according to claim 4,
Perform transmission signal weighting using any of the weighting factors received from the base station apparatus, or perform transmission signal processing without weighting,
The mobile station apparatus according to claim 4, wherein a signal indicating which of the weighting factors transmitted together with the transmission signal is selected or not used is transmitted to the base station apparatus. A mobile station apparatus that communicates with the base station apparatus according to claim 4,
Perform transmission signal weighting using any of the weighting factors received from the base station apparatus, or do not perform weighting, or perform transmission signal processing with previously used weighting factors ,
An identification signal indicating that any of the weighting factors transmitted together with the transmission signal has been selected or not used, or that a weighting factor used in the past has been used is transmitted to the base station apparatus. Mobile station device.   The mobile station apparatus according to claim 6, wherein a weighting factor used in the past is held for a predetermined period.   The base station apparatus that communicates with the mobile station apparatus according to claim 6, wherein a signal transmitted from the mobile station apparatus is demodulated based on the identification signal. The base station apparatus according to claim 1 or 4,
A base that performs demodulation processing on a signal transmitted from the mobile station device using a plurality of weighting factors notified to the mobile station device, and uses a demodulated signal without error detection as a transmission sequence Station equipment. A base station apparatus having a receiving circuit for receiving a plurality of different spatially multiplexed signals and having a function of notifying a mobile station apparatus of a coefficient for weighting the signal, from the mobile station apparatus to the base station apparatus Two or more weighting factors for weighting a signal to be transmitted to the mobile station apparatus using different channels, and a base station apparatus,
A mobile station device that communicates with the base station device, wherein one of the weighting factors received from the base station device is selected and transmitted together with a transmission signal weighted using the weighting factor. A mobile station apparatus, comprising: a mobile station apparatus that transmits to the base station apparatus a first signal indicating which of the weighting coefficients has been selected. A base station apparatus having a receiving circuit for receiving a plurality of different spatially multiplexed signals and having a function of notifying a mobile station apparatus of a coefficient for weighting the signal, from the mobile station apparatus to the base station apparatus Transmitting one or more weighting factors for weighting a signal to be transmitted to the mobile station device, and notifying the mobile station device of the weighting factor using a channel different from uplink signal allocation information. A base station device characterized by
A mobile station apparatus that communicates with the base station apparatus, and performs transmission signal weighting using any of the weighting factors received from the base station apparatus, or transmits a transmission signal without weighting And a mobile station device characterized by transmitting to the base station device a signal indicating which of the weighting factors transmitted with the transmission signal is selected or not used. Communications system. In a base station apparatus having a reception circuit for receiving a plurality of different spatially multiplexed signals and having a function of notifying a mobile station apparatus of a coefficient for weighting the signal,
Notifying the mobile station apparatus of two or more weighting factors for weighting signals transmitted from the mobile station apparatus to the base station apparatus using different channels;
In the mobile station device communicating with the base station device,
A first one representing which one of the weighting factors received from the base station apparatus is selected, and which one of the weighting factors transmitted is selected together with a transmission signal weighted using the weighting factor. Transmitting the above signal to the base station apparatus. In a base station apparatus having a reception circuit for receiving a plurality of different spatially multiplexed signals and having a function of notifying a mobile station apparatus of a coefficient for weighting the signal,
One or more weighting factors for weighting signals transmitted from the mobile station device to the base station device are transmitted to the mobile station device, and the weighting factors use channels different from uplink signal allocation information. Notifying to the base station device,
In the mobile station device communicating with the base station device,
A weighting factor that is transmitted with the transmission signal by performing the weighting processing of the transmission signal using any of the weighting factors received from the base station apparatus or performing the processing of the transmission signal without weighting Transmitting to the base station apparatus a signal indicating which one of the above has been selected or not used.   A program for causing a computer to execute the method according to claim 12 or 13.   The computer-readable recording medium which records the program of Claim 14.

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