JP5701332B2 - Base station apparatus, terminal apparatus, communication system, and communication method - Google Patents

Description

  The present invention relates to a base station device, a terminal device, a communication system, and a communication method.

  3GPP (Third Generation Partnership Project) in due WCDMA (Wideband Code Division Multiple Access), LTE (Long Term Evolution), LTE-A (LTE-Advanced) and IEEE (The Institute of Electrical and Electronics engineers) in due Wireless LAN, WiMAX (Worldwide In a wireless communication system such as Interoperability for Microwave Access, a base station (cell, transmitting station, transmitting device, eNodeB) and terminal (mobile terminal, receiving station, mobile station, receiving device, UE (User Equipment) The ent)), each comprise a plurality of receiving antennas, the MIMO (Multi Input Multi Output) technology, it is possible to achieve high-speed data transmission.

  In such a wireless communication system, a reference signal for channel state measurement (CSI-RS (Channel State Information-Reference Signal), a pilot signal, a known signal) is used that is composed of a known signal between the base station and the terminal. Thus, the transmission path condition between the base station and the terminal is measured, and based on the measurement result, the modulation scheme and the coding rate (MCS (Modulation and Coding Scheme)), the number of spatial multiplexing (number of layers, number of ranks) ), Adaptive control of precoding weights (precoding matrix, precoder) and the like makes it possible to realize more efficient data transmission. For example, the method described in Non-Patent Document 1 can be used.

  FIG. 20 is a schematic diagram illustrating an example of performing adaptive control when considering a downlink in which data transmission is performed in single cell communication. As illustrated in FIG. 20, the base station 2001 transmits (broadcasts) a transmission path condition measurement reference signal through a downlink (downlink, downlink) 2003. The terminal 2002 measures the transmission path condition of the downlink 2003 based on the received reference signal for transmission path condition measurement in the base station 2001, and transmits information (feedback information, report) for adaptive control to the uplink (uplink). (Uplink) 2004 to the base station 2001 for transmission (feedback).

  On the other hand, in a wireless communication system, a communication area can be expanded by adopting a cellular configuration in which a plurality of areas covered by a base station are arranged in a cell shape. In addition, by using different frequencies between adjacent cells (sectors), a terminal in the cell edge region can perform communication without receiving interference, but there is a problem regarding frequency utilization efficiency. Therefore, frequency utilization efficiency can be significantly improved by repeatedly using the same frequency in each cell (sector), but it is necessary to take measures against interference with terminals in the cell edge (cell edge) region.

  Under such circumstances, as multi-cell communication (cooperative communication), a method of reducing or suppressing interference with a terminal in a cell edge region by performing inter-cell cooperative communication that cooperates between adjacent cells has been studied. For example, Non-Patent Document 2 discusses a CoMP (Cooperative Multipoint) transmission system as such a system.

3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures (Release 8), 9 May 2010, 3GPP TS 36.213 V9.3.0 (2010-9 ) 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Further Advancements for E-UTRA Physical Layer.

  However, suitable feedback information differs between when the base station performs single-cell transmission to the terminal and when multi-cell transmission is performed. Since the conventional communication method is a communication system suitable for single cell communication, when a terminal performs multicell communication, if feedback information suitable for single cell communication is used, there is a problem that efficient data transmission cannot be performed. is there. Therefore, even when the base station and the terminal support both single-cell communication and multi-cell communication, it has been a factor that hinders improvement in transmission efficiency. Also in single cell communication, it is necessary to perform more flexible precoding processing, which is a factor that hinders improvement in transmission efficiency.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a base station that can efficiently support precoding processing in a communication system in which the base station can adaptively control the terminal. It is providing a terminal, a communication system, and a communication method.

  (1) The present invention has been made to solve the above-described problems, and a base station device according to one aspect of the present invention is configured such that a first base station device and a second base station device cooperate with a terminal device. The first base station apparatus in the communication system that performs communication, and the terminal apparatus selects, as feedback information, a codebook subset indicating precoding weights for performing the first communication and the second communication The terminal device is notified of codebook subset restriction information for restricting this.

  (2) Further, a base station apparatus according to an aspect of the present invention is the above base station apparatus, wherein the codebook subset restriction information for performing the first communication and the code for performing the second communication Each of the codebook subset restriction information is notified.

  (3) In addition, a base station apparatus according to an aspect of the present invention is the above base station apparatus, and notifies the shared codebook subset restriction information for performing the first communication and the second communication. It is characterized by that.

  (4) Moreover, the base station apparatus by 1 aspect of this invention is said base station apparatus, Comprising: The code book for performing the said 1st communication which the said terminal device selects using the said code book subset restriction information Switching information for designating feedback of either the information indicating the information or the information indicating the code book for performing the second communication is notified to the terminal device.

  (5) Moreover, the terminal device according to an aspect of the present invention is the terminal device in the communication system in which the first base station device and the second base station device cooperate with each other to communicate with the terminal device. Codebook for restricting selection of the terminal apparatus as feedback information with respect to a codebook subset indicating precoding weights for performing first communication and second communication notified by one base station apparatus Information indicating a code book for performing the first communication by selecting a code book for performing the first communication and a code book for performing the second communication, respectively, using subset restriction information; and Information indicating a code book for performing the second communication is notified to the first base station apparatus.

  (6) In addition, a terminal device according to an aspect of the present invention is the above-described terminal device, wherein the first base station device notifies the information indicating the codebook for performing the first communication or the first Information indicating the code book for performing the first communication or the second communication using switching information for designating feedback of any of the information indicating the code book for performing the communication of 2 Any one of the information indicating the code book for performing is notified to the first base station apparatus.

  (7) In addition, a base station apparatus according to an aspect of the present invention is a base station apparatus that communicates with a terminal apparatus, and the terminal apparatus performs a codebook subset indicating precoding weights for performing communication. It is characterized by notifying codebook subset power offset information for performing power offset control for a transmission path condition when calculating feedback information.

  (8) A terminal apparatus according to an aspect of the present invention is a terminal apparatus that communicates with a base station apparatus, and includes a codebook subset indicating precoding weights for performing communication that is notified by the base station apparatus. On the other hand, when the terminal device calculates feedback information, the codebook subset power offset information for performing power offset control for transmission path conditions is selected, and a codebook for performing the communication is selected, and the communication is performed. The base station apparatus is notified of information indicating a code book to be performed.

  (9) A communication system according to an aspect of the present invention is a communication system in which a first base station device and a second base station device cooperate with each other to communicate with a terminal device, and the first base station An apparatus provides code terminal subset restriction information for restricting selection of feedback information by the terminal apparatus for a code book subset indicating precoding weights for performing first communication and second communication. The terminal device selects the code book for performing the first communication and the code book for performing the second communication using the code book subset restriction information, and Information indicating a code book for performing communication 1 and information indicating a code book for performing second communication are notified to the first base station apparatus And wherein the Rukoto.

  (10) A communication system according to an aspect of the present invention is a communication system in which a first base station device and a second base station device cooperate with each other to communicate with a terminal device, and the first base station The apparatus includes: codebook subset restriction information for restricting the terminal apparatus from selecting as feedback information for a codebook subset indicating precoding weights for performing the first communication and the second communication; Feeding back either information indicating a code book for performing the first communication selected by the terminal device using the code book subset restriction information or information indicating a code book for performing the second communication The terminal device is notified of switching information for designating, using the codebook subset restriction information, Information indicating a code book for performing the first communication by selecting a code book for performing the first communication and a code book for performing the second communication, respectively, using the switching information, or Either of the information which shows the code book for performing said 2nd communication is notified to a said 1st base station apparatus, It is characterized by the above-mentioned.

  (11) A communication system according to an aspect of the present invention is a communication system in which a base station apparatus and a terminal apparatus communicate with each other, and the base station apparatus includes a codebook subset indicating precoding weights for performing communication. The terminal device is notified of codebook subset power offset information for performing power offset control on the transmission path status when calculating feedback information, and the terminal device uses the codebook subset power offset information. Then, a code book for performing the communication is selected, and information indicating the code book for performing the communication is notified to the base station apparatus.

  (12) In addition, in the communication method according to one aspect of the present invention, the communication of the first base station apparatus in the communication system in which the first base station apparatus and the second base station apparatus communicate with the terminal apparatus in cooperation with each other. A codebook subset restriction information for restricting selection of the terminal apparatus as feedback information for a codebook subset indicating precoding weights for performing the first communication and the second communication. It has the step which notifies to the said terminal device, It is characterized by the above-mentioned.

  (13) A communication method according to an aspect of the present invention is the communication method described above, and indicates a code book for performing the first communication selected by the terminal device using the code book subset restriction information. It has a step of notifying the terminal device of switching information for designating feedback of either information or information indicating a code book for performing the second communication.

  (14) A communication method according to an aspect of the present invention is a communication method for the terminal apparatus in a communication system in which the first base station apparatus and the second base station apparatus communicate with the terminal apparatus in cooperation. In order to restrict the terminal device from selecting as feedback information for the codebook subset indicating the precoding weight for performing the first communication and the second communication notified by the first base station device Selecting a code book for performing the first communication and a code book for performing the second communication using the code book subset restriction information, and a code for performing the first communication A step of notifying the first base station apparatus of information indicating a book and information indicating a code book for performing the second communication. And butterflies.

  (15) A communication method according to an aspect of the present invention is the communication method described above, wherein the first base station apparatus notifies the information indicating the code book for performing the first communication or the first Information indicating the code book for performing the first communication or the second communication using switching information for designating feedback of any of the information indicating the code book for performing the communication of 2 A step of notifying the first base station apparatus of any information indicating a code book for performing

  (16) A communication method according to an aspect of the present invention is a communication method of a base station apparatus that communicates with a terminal apparatus, wherein the terminal is applied to a codebook subset indicating precoding weights for performing communication. The apparatus includes a step of notifying codebook subset power offset information for performing power offset control on a transmission path condition when calculating feedback information.

  (17) A communication method according to an aspect of the present invention is a communication method for a terminal apparatus that communicates with a base station apparatus, and is a code indicating precoding weight for communication that is notified by the base station apparatus. A step of selecting a codebook for performing the communication using codebook subset power offset information for performing power offset control for transmission path conditions when the terminal apparatus calculates feedback information for the book subset. And a step of notifying the base station apparatus of information indicating a code book for performing the communication.

  According to the present invention, the base station can efficiently support the precoding process for the terminal.

It is the schematic which shows an example which performs adaptive control at the time of considering the downlink which performs data transmission in the multicell communication which concerns on the 1st Embodiment of this invention. It is a schematic block diagram which shows the structure of the primary base station 101 which concerns on the 1st Embodiment of this invention. It is a schematic block diagram which shows the structure of the secondary base station 102 which concerns on the 1st Embodiment of this invention. It is a schematic block diagram which shows the structure of the terminal 103 which concerns on the 1st Embodiment of this invention. It is a schematic block diagram which shows the structure of the feedback information generation part 404 which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the reference signal for a 1st transmission line condition which the primary base station 101 maps, a data signal or a control information signal, and the muted resource element. It is a figure which shows an example of the 2nd transmission-path condition measurement reference signal, the data signal or control information signal which the secondary base station 102 maps, and the muted resource element. It is a figure which shows an example of the code book subset when the number of antenna ports is 2. It is a figure which shows an example of the number of code books with respect to the number of antenna ports. It is a figure which shows an example of the notification procedure of the control information which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the notification procedure of the control information which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the notification procedure of the control information which concerns on the 1st Embodiment of this invention. It is a schematic block diagram which shows the structure of the feedback information generation part 404 which concerns on the 2nd Embodiment of this invention. It is a figure which shows an example of the notification procedure of the control information which concerns on the 2nd Embodiment of this invention. It is a figure which shows an example of the notification procedure of the control information which concerns on the 2nd Embodiment of this invention. It is a figure which shows an example of the measurement sub-frame identification information which concerns on the 2nd Embodiment of this invention. It is a figure which shows an example of the notification procedure of the control information which concerns on the 2nd Embodiment of this invention. It is a figure which shows an example of the codebook subset electric power offset information which concerns on the 3rd Embodiment of this invention. It is a schematic block diagram which shows the structure of the feedback information generation part 404 which concerns on the 3rd Embodiment of this invention. It is the schematic which shows an example which performs adaptive control at the time of considering the downlink which performs data transmission in single cell communication.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described. The communication system according to the first embodiment includes a primary base station (first base station, first node) as a base station (transmitter, cell, transmission point, transmission antenna group, transmission antenna port group, component carrier, eNodeB). Communication device, serving base station, anchor base station, first component carrier) and secondary base station (second base station device, cooperative base station group, cooperative base station set, second communication device, cooperative base station, 2nd component carrier), a terminal (terminal device, mobile terminal, receiving point, receiving terminal, receiving device, third communication device, receiving antenna group, receiving antenna port group, UE). A plurality of secondary base stations may be provided.

  FIG. 1 is a schematic diagram illustrating an example in which adaptive control is performed when considering a downlink in which data transmission is performed in multi-cell communication according to the first embodiment of the present invention. In FIG. 1, the terminal 103 is located in each cell edge region (boundary region) in the primary base station 101 and the secondary base station 102, and performs multicell communication from the primary base station 101 and the secondary base station 102. The terminal 103 receives the reference signal for transmission path condition measurement in the primary base station 101 transmitted through the downlink 104 between the primary base station 101 and the terminal 103. Further, the terminal 103 receives a reference signal for transmission path condition measurement in the secondary base station 102 transmitted through the downlink 105 between the secondary base station 102 and the terminal 103. The terminal 103 estimates the transmission path conditions of the downlink 104 and the downlink 105 by using the transmission path condition measurement reference signals in the primary base station 101 and the secondary base station 102. Terminal 103 generates information (feedback information) for performing adaptive control based on the estimated transmission path condition. Terminal 103 transmits the feedback information to primary base station 101 using uplink 1606. The primary base station 101 performs adaptive control and scheduling of the data signal for the terminal 103 based on the feedback information, and performs multi-cell communication with the primary base station 102 through a line (X2 interface) 107 using an optical fiber, a relay technology, or the like. Control information is transmitted. The primary base station 101 and the secondary base station 102 use the downlink 104 and the downlink 105 to transmit data signals directed to the terminal 103 in cooperation with each other.

  Even when a data signal is transmitted by multi-cell communication between the primary base station 101 and the secondary base station 102, the terminal 103 can receive the data signal without recognizing that the secondary base station 102 is performing cooperative communication. Processing can be performed. That is, the primary base station 101 can use control information used when performing single cell communication even when performing multicell communication with the terminal 103. Specifically, when the primary base station 101 and the secondary base station 102 transmit the same data signal to the terminal 103, the terminal 103 transmits the control information notified from the primary base station as in the case of single cell communication. By performing processing, reception processing can be performed without performing special processing.

  FIG. 2 is a schematic block diagram showing the configuration of the primary base station 101 according to the first embodiment of the present invention. Here, the primary base station 101 is a base station that receives feedback information from the terminal 103, a base station that transmits control information for the terminal 103 (for example, information transmitted by PDCCH (Physical Downlink Control Channel), etc.), etc. 103 is one of base stations that perform cooperative communication with 103. 2, the primary base station 101 includes a transmission signal generation unit 201, a first transmission path condition measurement reference signal multiplexing unit 202, a transmission unit 203, a reception unit 204, a feedback information processing unit 205, and an upper layer 206. Yes.

  The receiving unit 204 receives a data signal including feedback information transmitted from the terminal 103 through an uplink 106 (for example, PUCCH (Physical Uplink Channel), PUSCH (Physical Uplink Shared Channel, etc.)) 106.

  The reception unit 204 performs reception processing for transmission processing performed by the terminal 103 for signal transmission, such as OFDM demodulation processing, demodulation processing, and decoding processing, on the signal received by the reception antenna, and from among the received signals The feedback information is identified and output to the feedback information 205.

  In addition, when there are a plurality of terminals 103 that communicate with the primary base station 101, SC-FDMA (Single carrier-division multiple access), Clustered DFT-S-OFDM (Discrete Fourier Transform- The data signal of the terminal 103 can be multiplexed using various multiple access schemes such as (Spread-OFDM), OFDMA, time division multiple access, and code division multiple access. Further, in the primary base station 101, various methods can be used as a method for identifying feedback information for each terminal 103. For example, the primary base station 101 designates resources (elements for signal transmission divided by time, frequency, code, spatial domain, etc.) for each terminal 103 to transmit feedback information, and the terminal 103 designates the designated information By transmitting feedback information with resources, the primary base station 101 can be identified. It can also be realized by adding identification information unique to each terminal 103 to each feedback information.

  The feedback information processing unit 205 generates adaptive control information for performing adaptive control on the data signal to be transmitted to the terminal 103 based on the input feedback information. When feedback information for the primary base station 101 is included, adaptive control information in the primary base station 101 is generated and output to the transmission signal generation unit 201.

  The transmission signal generation unit 201 can adaptively control encoding processing, modulation processing, layer mapping processing, precoding processing, resource element mapping processing, and the like in the primary base station 101 based on the adaptive control information. The adaptive control information may be output to an upper layer (not shown).

  Further, when feedback information for the secondary base station 102 is included, adaptive control information for encoding processing, modulation processing, layer mapping processing, precoding processing, resource element mapping processing, etc. in the secondary base station 102 described later is generated, and X2 The data is output to the secondary base station 102 through a line such as an interface (preferably a wired line such as an optical fiber or a specific wireless line using a relay technology). The line connecting the base stations can be used for various purposes other than the case where the adaptive control information is communicated from the primary base station 101 to the secondary base station 102, for example, from the secondary base station 102 to the primary base station. Base station information and control information for performing cooperative communication with the station 101 can also be communicated. When feedback information for each base station is not included, the control may be performed by a predetermined method.

  Here, an adaptive control method based on feedback information will be described. Various methods can be used for the feedback information. In the following, recommended transmission format information (implicit transmission path status information) for the base station and information (explicit transmission path status, transmission channel) indicating the transmission path status (transmission path status, transmission channel). A case where the sit transmission path status information) is used will be described.

First, in the case of recommended transmission format information for the base station as feedback information, it is assumed that a known transmission format is indexed in advance for both the base station and the terminal, and the terminal feeds back information using the transmission format, and the base station Performs adaptive control using the information. Specifically, since CQI (Channel Quality Indicator) is information indicating a coding rate and a modulation scheme, the coding process and the modulation process can be controlled, respectively. Since PMI (Precoding Matrix Index) is information indicating a precoding matrix, precoding processing can be controlled. RI (Rank
Indicator) is information indicating the number of layers, and can be controlled with respect to a layer mapping process or an upper layer that generates a code word. Further, when feedback information related to mapping to resources is also included, it is possible to control the resource element mapping process. Here, the PMI can be divided into a plurality of types according to the data transmission method, purpose, application, and the like, details of which will be described later.

  Next, in the case of information indicating the transmission path condition as feedback information, the terminal feeds back the transmission path condition information with the base station using the transmission path condition measurement reference signal from the base station. At that time, the information amount of the information indicating the transmission path condition may be reduced by using various methods such as eigenvalue decomposition and quantization. In the base station, the terminal is controlled using the information on the fed back transmission path condition. For example, the base station can determine the coding rate and modulation scheme, the number of layers, and the precoding matrix based on the fed back information so that the optimum reception can be performed when the terminal receives it. Can be used.

  The upper layer 206 generates a data signal for the terminal 103 and outputs the data signal to the transmission signal generation unit 201.

  The transmission signal generation unit 201 performs adaptive control based on the adaptive control information output from the feedback information 205 on the data signal output from the higher layer 206 to generate a transmission signal for the terminal 103. Specifically, the transmission signal generation unit 201 includes an encoding process for performing error correction encoding, a scramble process for applying a scramble code unique to the terminal 103, a modulation process for using a multi-level modulation method, Layer mapping processing for performing spatial multiplexing such as MIMO, precoding processing for performing phase rotation, beam forming, and the like are performed.

Here, the precoding process is performed so that the terminal 103 can efficiently receive (for example, the reception power is maximized, the interference from the adjacent cell is reduced, or the interference to the adjacent cell is reduced). Thus, it is preferable to perform phase rotation or the like on the generated signal. Also, processing by a predetermined precoding matrix, CDD (Cyclic Delay Diversity), transmission diversity (SFBC (Spatial)
Frequency Block Code), STBC (Spatial Time
Block Code), TSTD (Time Switched Transmission Diversity), FSTD (Frequency Switched)
Transmission Diversity) etc. can be used, but is not limited thereto. Here, when a PMI divided into a plurality of types is fed back, a precoding process can be performed by performing an operation such as multiplication on the plurality of PMIs.

  Here, before performing precoding processing on the transmission signal, a reference signal for data signal demodulation (DM-RS (Demodulation Reference Signal), DRS (Dedicated Reference Signal)) for the terminal 103 to demodulate the transmission signal, Precoded RS, user-specific reference signal, UE-specific RS) can be multiplexed. The data signal demodulation reference signal is subjected to precoding processing together with a transmission signal to the terminal 103. The reference signal for data signal demodulation in each layer is either code division multiplexing (CDM; Code Division Multiplexing) or frequency division multiplexing (FDM; Frequency Division Multiplexing) using orthogonal codes such as Walsh codes or the like. Use together to make them orthogonal.

  The first transmission channel state measurement reference signal multiplexing unit 202 is configured to measure the transmission channel state (first transmission channel state) of the downlink 104 between the primary base station 101 and the terminal 103. 101 and terminal 103 generate first known transmission path condition measurement reference signals (cell-specific reference signal, CRS (Common RS), Cell-specific RS, Non-precoded RS) and transmit the input transmission signal. Multiplex on the other hand. At this time, any signal (sequence) may be used as the first transmission path condition measurement reference signal as long as both the primary base station 101 and the terminal 103 are known signals. For example, a random number or a pseudo noise sequence based on a parameter assigned in advance such as a number (cell ID) unique to the primary base station 101 can be used. In addition, as a method of orthogonalizing between antenna ports, a method of making resource elements that map the first reference signal for transmission path condition measurement mutually null (zero) between antenna ports, code division multiplexing using a pseudo-noise sequence A method, a method combining them, or the like can be used. Note that the transmission path condition measurement reference signal does not have to be multiplexed in all subframes, but may be multiplexed only in some subframes.

  The transmission unit 203 performs mapping processing of the transmission signal output from the first transmission path condition measurement reference signal multiplexing unit 202 on the resource element of each antenna port, and performs transmission processing from the transmission antenna.

  FIG. 3 is a schematic block diagram showing the configuration of the secondary base station 102 according to the first embodiment of the present invention. Here, the secondary base station 102 is a base station excluding the primary base station 101 described with reference to FIG. 1 among base stations that perform cooperative communication with the terminal 103. In FIG. 3, the secondary base station 102 includes a transmission signal generation unit 301, a second transmission path condition measurement reference signal multiplexing unit 302, a transmission unit 303, and an upper layer 304.

  The transmission signal generation unit 301 adaptively controls each of the encoding process, the modulation process, the layer mapping process, the precoding process, and the resource element mapping process based on the adaptive control information for the terminal 103 output from the primary base station. The adaptive control information is input from the primary base station 101 through a line such as an X2 interface. Further, in a cooperative communication scheme (for example, Joint Transmission, Dynamic Cell Selection, etc.) in which an information data signal is transmitted from the secondary base station 102 to the terminal 103 as well, an information data signal from the primary base station 101 to the terminal 103 is a line such as an X2 interface. Is entered through.

  Hereinafter, the operation of the secondary base station 102 will be described with a focus on the differences from the primary base station 101 described with reference to FIG.

  The operation of the precoding process in the transmission signal generation unit 301 can be changed according to the cooperative communication scheme for the terminal 103. First, in a coordinated communication scheme in which an information data signal is transmitted from the secondary base station 102 to the terminal 103, such as joint transmission, joint processing, dynamic cell selection transmission, and the like, It is preferable to perform precoding processing so that the terminal 103 can perform optimal reception in cooperation with the primary base station 101. Also, in coordinated communication schemes such as coordinated scheduling and coordinated beamforming, information data signals of other mobile terminals are reduced so as to reduce interference from the secondary base station 102 to the terminal 103. It is preferable to perform precoding processing (including transmission power control).

  The second transmission path condition measurement reference signal generation unit 302 is configured to measure the downlink 105 transmission path condition (second transmission path condition) between the secondary base station 102 and the terminal 103. 102 and the terminal 103 generate a second known transmission path condition measurement reference signal and multiplex them with the transmission signal generated by the transmission signal generation unit 301. At this time, any signal (sequence) can be used as the second transmission path condition measurement reference signal as long as both the secondary base station 102 and the terminal 103 are known signals. For example, a random number or a pseudo noise sequence based on a parameter assigned in advance such as a number (cell ID) unique to the secondary base station 102 can be used. In addition, as a method of orthogonalizing between antenna ports, a method of making resource elements that map the second transmission path condition measurement reference signal mutually null (zero) between antenna ports, code division multiplexing using a pseudo noise sequence A method or the like can be used.

  FIG. 4 is a schematic block diagram showing the configuration of the terminal 103 according to the first embodiment of the present invention. In FIG. 4, the terminal 103 includes a reception unit 401, a reception signal processing unit 402, a control unit 403, a feedback information generation unit 404, a transmission unit 405, and an upper layer 406.

  The reception unit 401 receives signals transmitted from the primary base station 101 and the secondary base station 102 by using at least one reception antenna number (the number of reception antenna ports), and performs conversion processing from a radio frequency to a baseband signal. I do. The received signal processing unit 402 removes the added guard interval, performs time-frequency conversion processing by Fast Fourier Transform (FFT) or the like, and converts the signal into a frequency domain signal. Further, the received signal processing unit 402 demaps (separates) the signals mapped by the primary base station 101 and the secondary base station 102. When the demapped signal includes a data signal addressed to terminal 103, reception signal processing section 402 outputs the data signal to data signal processing section 403. When the demapped signal includes the first transmission path condition measurement reference signal and / or the second transmission path condition measurement reference signal, the reception signal processing unit 402 transmits those transmission path condition measurement reference signals. Is output to the feedback information generation unit 404. The control information signal is shared by the entire terminal 103 (including the upper layer) and is used for various controls in the terminal 103 such as demodulation of a data signal (not shown).

  The data signal processing unit 403 performs propagation path estimation processing, propagation path compensation processing (filter processing), layer demapping processing, demodulation processing, descrambling processing, decoding processing, and the like on the input data signal, and performs higher layer It outputs to 406. In the propagation path estimation process, amplitude and phase fluctuations (frequency response, transmission) in each resource element for each layer (rank, spatial multiplexing) based on the data signal demodulation reference signal multiplexed on the input data signal Function) is estimated (propagation path estimation), and a propagation path estimation value is obtained. Note that the resource element to which the data signal demodulation reference signal is not mapped is interpolated in the frequency direction and the time direction based on the resource element to which the data signal demodulation reference signal is mapped, and performs propagation path estimation. In the propagation path compensation processing, propagation path compensation is performed on the input data signal using the estimated propagation path estimation value, and the data signal for each layer is detected (restored). As the detection method, ZF (Zero Forcing) standard, MMSE (Minimum Mean Square Error) standard equalization, interference removal, or the like can be used. In the layer demapping process, the demapping process is performed on the signal for each layer to each codeword. Thereafter, processing is performed for each codeword. In the demodulation process, demodulation is performed based on the modulation method used. In the descrambling process, the descrambling process is performed based on the used scramble code. In the decoding process, an error correction decoding process is performed based on the applied encoding method.

  On the other hand, the feedback information generation unit 404 generates feedback information based on the input transmission path condition measurement reference signal.

  FIG. 5 is a schematic block diagram showing the configuration of the feedback information generation unit 404 according to the first embodiment of the present invention. In FIG. 5, the feedback information generation unit 404 includes a transmission path condition measurement unit 501 and a feedback information calculation unit 502.

  The transmission path status measurement unit 501 measures the transmission path status of the transmission antenna in each base station with respect to the reception antenna at the terminal 103 for each base station using the received transmission path status measurement reference signal, and transmits the transmission for each base station. Generate road condition measurements. Next, the feedback information calculation unit 502 calculates feedback information based on the generated transmission path condition estimated value. At this time, the feedback information calculation unit 502 also receives codebook subset restriction information included in the control information signal and the like, and is considered when calculating the feedback information. Details will be described later.

  The unit for generating feedback information is in the frequency direction (for example, for each subcarrier, for each resource element, for each resource block, for each subband composed of a plurality of resource blocks), for the time direction (for example, for each OFDM symbol, Subframes, slots, radio frames, etc.), spatial directions (for example, antenna ports, transmission antennas, reception antennas, etc.) can be used, and these can be combined.

  Moreover, when generating the recommended transmission format information for the base station as feedback information, various methods can be used for the generation. For example, first, the maximum number of layers that can be spatially multiplexed is obtained using eigenvalue decomposition or the like based on the generated transmission path condition estimated value, and an RI is generated. Based on the generated RI and transmission path condition estimation value, a precoding matrix or the like that can be optimally received is estimated, and a PMI is generated. For the generation of PMI, for example, a precoding matrix that is optimal when cooperative communication is performed may be selected by multiplying the generated channel state estimation value by generating a precoding matrix as a candidate. Further, an optimal precoding matrix may be selected from candidate precoding matrices using eigenvalue decomposition or the like. At this time, candidate precoding matrices are determined based on the input codebook subset restriction information. Next, based on the generated RI, PMI, and transmission path condition estimated value, a modulation scheme and a coding rate for the information data signal are selected, and a CQI is generated. The generation of the CQI includes, for example, a received signal power to interference / noise power ratio (SINR (Signal to Interference plus Noise power Ratio)), a received signal power to interference power ratio (SIR (Signal to Interference power Ratio)), and a received signal. When measuring the power-to-noise power ratio (SNR (Signal to Noise Power Ratio)), path loss, etc., and setting up a CQI look-up table that satisfies the required quality for those measured values, and performing collaborative communication May be obtained and the CQI may be determined from a lookup table.

  The generated feedback information is input to the transmission unit 405. The transmission unit 405 performs encoding processing, modulation processing, OFDM signal generation processing, guard interval insertion processing, frequency conversion processing, etc. in order to transmit (feedback) the feedback information output from the feedback information generation unit 404 to the primary base station 101. To generate an uplink transmission signal. Furthermore, the transmission unit 405 transmits the generated uplink transmission signal to the primary base station 101 via the uplink (PUCCH or PUSCH). The uplink transmission signal may be transmitted not only to the primary base station 101 but also to the secondary base station 102.

  Further, as a method of feeding back the uplink transmission signal including the feedback information generated as described above to the primary base station 101, for example, it is divided into a plurality of subframes and transmitted through the PUCCH designated by the primary base station 101. Can do. Also, all or part of the generated feedback information can be transmitted in one subframe through the PUSCH designated by the primary base station 101. At that time, it may be transmitted together with the information data signal from the terminal 103.

  FIG. 6 is a diagram illustrating an example of a first transmission path condition measurement reference signal, a data signal or control information signal, and a muted resource element mapped by the primary base station 101. FIG. 6 shows a case where respective signals are mapped when the number of antenna ports of the primary base station 101 is eight. FIG. 6 shows two resource blocks in one subframe, and one resource block is composed of 12 subcarriers in the frequency direction and 7 OFDM symbols in the time direction. Each subcarrier in one OFDM symbol is called a resource element. Of each subframe, the seven OFDM symbols before and after in the time direction are also called slots.

  The shaded resource elements represent the first transmission path condition measurement reference signals of the antenna ports 1 to 8 as C1 to C8, respectively. A resource element filled in with black represents a muted resource element, and the resource element is null (zero). In this example, the muted resource element corresponds to the resource element to which the second transmission path condition measurement reference signal of the secondary base station 102 shown in FIG. 7 described later is mapped. Further, the resource element filled in white maps a data signal or a control information signal. Note that the number of data signal or control information signal layers (rank number) can be a maximum of eight, for example, the number of data signal layers can be two and the number of control information signal layers can be one.

  Here, the number of resource blocks can be changed according to the frequency bandwidth (system bandwidth) used by the communication system. For example, 6 to 110 resource blocks can be used, and the total system bandwidth can be increased to 110 or more by frequency aggregation. Usually, the component carrier is composed of 100 physical resource blocks, and the total system bandwidth can be made 500 physical resource blocks with 5 component carriers with a guard band between the component carriers. Expressing this in terms of bandwidth, for example, the component carrier is configured at 20 MHz, and the total system bandwidth can be set to 100 MHz with five component carriers with the guard band between the component carriers.

  FIG. 7 is a diagram illustrating an example of a second transmission path condition measurement reference signal, a data signal or a control information signal, and a muted resource element mapped by the secondary base station 102. Here, the second transmission path condition measurement reference signal is mapped so as to be FDM with respect to the first transmission path condition measurement reference signal described in FIG. In the example of FIG. 7, the frequency direction is shifted by one subcarrier with respect to the example of FIG. Further, the muted resource element corresponds to the resource element to which the first transmission path state measurement reference signal of the primary base station 101 shown in FIG. 6 is mapped.

  The position and signal sequence to which each channel state measurement reference signal is mapped may be notified or notified to the terminal 103 as control information (including RRC (Radio Resource Control) signaling), and other control such as cell ID may be performed. The terminal 103 may be identified based on the information. Further, among the plurality of antenna ports, only the position and signal sequence to which the channel state measurement reference signal for one antenna port is mapped can be notified, broadcast, or identified. The antenna port can also be identified.

  In the example shown in FIG. 6 and FIG. 7, the primary base station 101 and the secondary base station 102 respectively select the resource elements to which the reference signals for transmission path status measurement are mapped, from among the data signal or the control information signal to be mapped. Muting. That is, the resource element of the second transmission path condition measurement reference signal mapped by the secondary base station 102 among the information data signal or control information signal mapped by the primary base station 101 is muted. Moreover, the resource element of the reference signal for the 1st transmission line condition measurement which the primary base station 101 maps among the information data signals or control information signals which the secondary base station 102 maps is muted. Note that all or part of the resource elements to be muted may be used. By muting, the terminal 103 can efficiently estimate the transmission path condition in the case of cooperative communication. As a muting method, first, a data signal or a control information signal is mapped, and then a resource element signal mapped by a reference signal for transmission path condition measurement of another base station that cooperates may be thinned out (puncturing). ). Further, the data signal or the control information signal may be mapped (rate matching) so as to avoid the resource element to which the reference signal for transmission path condition measurement of another base station that cooperates is mapped.

  Hereinafter, codebook subset restriction information and PMI feedback information used in the first embodiment will be described. In the following description, the code book is a precoding weight that is known as a code book in the primary base station 101, the secondary base station 102, and the terminal 103. A codebook subset is a small group of such codebooks.

  FIG. 8 is a diagram illustrating an example of a codebook subset when the number of antenna ports is two. In FIG. 8, four codebooks (W10, W11, W12, W13) when the rank number is 1 and two codebooks (W21, W22) when the rank number is 2 are shown. That is, when the number of antenna ports is 2, the number of codebooks is 6.

  The terminal 103 selects a suitable code book from the code book subset using the reference signal for transmission path condition measurement of each base station, and feeds it back to the primary base station 101 as PMI. At this time, each base station can make terminal 103 restrict | limit part or all of the codebook subset which can be selected as PMI. In order to realize such restriction, the primary 101 notifies the terminal 103 of codebook subset restriction information as control information for the terminal 103.

  The code book subset restriction information is control information in a bitmap format corresponding to each code book. Specifically, 1-bit control information is set for each codebook, and “0” is set to restrict selection as a PMI, and “1” is set otherwise. That is, in the example shown in FIG. 8, the codebook subset restriction information when the number of antenna ports is 2 is information in a 6-bit bitmap format. For example, when the number of ranks of 2 is restricted, the codebook subset restriction information of the codebook corresponding to W21 and W22 may be set to “0”.

  FIG. 9 is a diagram illustrating an example of the number of code books with respect to the number of antenna ports. In addition to the case where the number of antenna ports shown in FIG. 8 is 2, FIG. 9 also shows the number of codebooks for each rank when the number of antenna ports is 4 and 8. When the number of antenna ports is 4, there are 16 codebooks for each rank up to 4. The codebook subset restriction information at this time is 64-bit bitmap format information. In the case of 8 antenna ports, two partial precoding weights can be used to specify precoding weights. At this time, assuming that the partial precoding weights are W1 and W2, the precoding weights can be expressed by operations (four arithmetic operations, weighted multiplication, etc.) of W1 and W2. Also, codebooks are set for the partial precoding weights of W1 and W2, respectively. In the example shown in FIG. 9, the number of codebooks for W1 and W2 is set depending on the number of ranks. The codebook subset restriction information at this time is 109-bit bitmap format information.

  Here, the codebook subset is information that is known in advance between each base station and the terminal 103, and is information that depends on the number of antenna ports of the base station. That is, the terminal 103 can identify the number of antenna ports of the base station based on the control information broadcast by each base station, and can recognize the codebook subset used by the base station.

  The codebook subset restriction information is control information unique to the terminal 103 and is information notified from the primary base station 101. As a notification method, the primary base station 101 can be included in control information (PDCCH, RRC signaling, etc.) addressed to the terminal 103.

  In an example in the first embodiment of the present invention, the primary base station 101 is configured for multi-cell communication (second communication) in addition to codebook subset restriction information for single-cell communication (first communication). Codebook subset restriction information can also be notified. In this example, a codebook subset shared by single cell communication and multicell communication is used.

  FIG. 10 is a diagram illustrating an example of a control information notification procedure according to the first embodiment of the present invention. The primary base station 101 notifies the terminal 103 of the codebook subset restriction information for single cell communication and the codebook subset restriction information for multicell communication. Based on the restriction information, terminal 103 can select a codebook subset that can be selected as a PMI for single cell communication and a PMI for multicell communication from among predefined single cell communication / multicell communication shared codebook subsets. Set a selectable codebook subset as The primary base station 101 transmits a first transmission path condition measurement reference signal, and the secondary base station 102 transmits a second transmission path condition measurement reference signal. Terminal 103 uses each of these channel status measurement reference signals to measure each channel status, and from among the codebook subsets that can be selected as the set PMI, PMI and multicell communication suitable for single cell communication A PMI suitable for each is selected. The terminal 103 notifies the selected PMI suitable for single cell communication and PMI suitable for multicell communication. The primary base station 101 schedules data transmission to the terminal 103 based on each notified PMI.

  By using the method described above, the primary base station 101 can perform scheduling using PMI suitable for single-cell communication and PMI suitable for multi-cell communication, so that transmission characteristics can be improved. Further, it is not necessary to define a code book subset for single cell communication and a code book subset for multi cell communication, respectively, and optimization for precoding processing of single cell communication and multi cell communication can be realized.

  In another example of the first embodiment of the present invention, the codebook subset for single cell communication and the codebook subset for multicell communication are respectively defined in advance as independent codebook subsets. Shared codebook subset restriction information can be notified. In this example, the number of codebooks for single cell communication and the number of codebooks for multicell communication are preferably the same.

  FIG. 11 is a diagram illustrating an example of a control information notification procedure according to the first embodiment of the present invention. The primary base station 101 notifies the terminal 103 of single-cell communication / multi-cell communication shared codebook subset restriction information. Based on the restriction information, terminal 103 can select a codebook subset and multicell communication that can be selected as a PMI for single cell communication from codebook subsets for single cell communication and codebook subsets for multicell communication. Selectable codebook subsets are set as PMIs. The primary base station 101 transmits a first transmission path condition measurement reference signal, and the secondary base station 102 transmits a second transmission path condition measurement reference signal. Terminal 103 uses each of these channel status measurement reference signals to measure each channel status, and from among the codebook subsets that can be selected as the set PMI, PMI and multicell communication suitable for single cell communication A PMI suitable for each is selected. The terminal 103 notifies the selected PMI suitable for single cell communication and PMI suitable for multicell communication. The primary base station 101 schedules data transmission to the terminal 103 based on each notified PMI.

  By using the method described above, the primary base station 101 can perform scheduling using PMI suitable for single-cell communication and PMI suitable for multi-cell communication, so that transmission characteristics can be improved. In addition, since the codebook subset restriction information for single cell communication and the codebook subset restriction information for multicell communication are shared, optimization to single cell communication and multicell communication precoding processing can be performed without increasing the overhead of control information. realizable.

  In another example in the first embodiment of the present invention, the primary base station 101 communicates with the secondary base station in addition to the codebook subset restriction information for communication with the primary base station (first communication). The codebook subset restriction information for (second communication) can also be notified. In this example, a codebook subset shared by the primary base station and the secondary base station is used.

  FIG. 12 is a diagram illustrating an example of a control information notification procedure according to the first embodiment of the present invention. The primary base station 101 notifies the terminal 103 of the codebook subset restriction information for the primary base station and the codebook subset restriction information for the secondary base station, respectively. Based on the restriction information, the terminal 103 can select a codebook subset and a secondary base station that can be selected as a PMI for the primary base station from a predefined primary base station / secondary base station shared codebook subset. A selectable codebook subset is set as the PMI. The primary base station 101 transmits a first transmission path condition measurement reference signal, and the secondary base station 102 transmits a second transmission path condition measurement reference signal. The terminal 103 measures each transmission path condition using the reference signal for transmission path condition measurement, and selects the PMI and secondary base station suitable for the primary base station from the codebook subsets that can be selected as the set PMI. Select a PMI suitable for the station. Terminal 103 notifies PMI suitable for the selected primary base station and PMI suitable for the secondary base station, respectively. The primary base station 101 schedules data transmission to the terminal 103 based on each notified PMI.

  By using the method described above, the primary base station 101 can perform scheduling using a PMI suitable for the primary base station and a PMI suitable for the secondary base station, so that transmission characteristics can be improved. In addition, it is not necessary to define a codebook subset for the primary base station and a codebook subset for the secondary base station, respectively, and the primary base station and the secondary base station can be optimized for precoding processing.

  In another example of the first embodiment of the present invention, the primary base station codebook subset and the secondary base station codebook subset are defined in advance as independent codebook subsets, and the primary base station and the secondary base The codebook subset restriction information shared by the station can be notified. In this example, the number of codebooks for the primary base station and the number of codebooks for the secondary base station are preferably the same.

  The primary base station 101 notifies the terminal 103 of the primary base station / secondary base station shared codebook subset restriction information. Based on the restriction information, terminal 103 can select a codebook subset and secondary base station that can be selected as a PMI for the primary base station from a predefined codebook subset for primary base station and codebook subset for secondary base station. Each selectable codebook subset is set as the PMI for the station. The primary base station 101 transmits a first transmission path condition measurement reference signal, and the secondary base station 102 transmits a second transmission path condition measurement reference signal. The terminal 103 measures each transmission path condition using the reference signal for transmission path condition measurement, and selects the PMI and secondary base station suitable for the primary base station from the codebook subsets that can be selected as the set PMI. Select a PMI suitable for the station. Terminal 103 notifies PMI suitable for the selected primary base station and PMI suitable for the secondary base station, respectively. The primary base station 101 schedules data transmission to the terminal 103 based on each notified PMI.

  By using the method described above, the primary base station 101 can perform scheduling using a PMI suitable for the primary base station and a PMI suitable for the secondary base station, so that transmission characteristics can be improved. In addition, since code base subset restriction information for primary base stations and code book subset restriction information for secondary base stations are shared, it is optimal for precoding processing of primary base stations and secondary base stations without increasing the overhead of control information. Can be realized.

  The codebook subset restriction information is control information specific to each base station, and may be information broadcast from the primary base station 101. As a broadcast method, the primary base station 101 can be included in broadcast information (BCH (Broadcast Channel), MIB (Master Information Block), SIB (System Information Block), etc.).

  The code book subset restriction information is information set for each code book, but may be information set for a group of a plurality of code books. Specifically, the code book subset restriction information may be information set for a group of all or part of the code book for each rank. For example, W10 and W12 described in FIG. 8 can be grouped, and W11 and W13 can be grouped. Further, the code book subset restriction information may be information set for a group of a part or all of the code book for each code book index over a plurality of ranks. For example, W11 and W21 described in FIG. 8 can be grouped, and W12 and W22 can be grouped. As described above, the overhead of the codebook subset restriction information can be reduced by grouping a plurality of codebooks.

(Second Embodiment)
In the first embodiment, a case has been described in which a plurality of PMIs are notified based on a plurality of codebook subsets. In the second embodiment of the present invention, a case is described in which the selected PMI is notified based on a plurality of codebook subsets. The second embodiment of the present invention will be described below with reference to the drawings.

  FIG. 13 is a schematic block diagram showing the configuration of the feedback information generation unit 404 according to the second embodiment of the present invention. In FIG. 13, the feedback information generation unit 404 includes a transmission path condition measurement unit 1301, a feedback information calculation unit 1302, and a selection unit 1303.

  The transmission path condition measurement unit 1301 measures the transmission path condition of the transmission antenna in each base station with respect to the reception antenna at the terminal 103 for each base station using the received transmission path condition measurement reference signal, and transmits the transmission for each base station. Generate road condition measurements. Next, feedback information calculation section 1302 calculates feedback information based on the generated transmission path condition estimated value. At this time, the feedback information calculation unit 1302 also receives codebook subset restriction information included in the control information signal and the like, and takes it into account when calculating feedback information.

  In an example in the second embodiment of the present invention, the primary base station 101 can notify the codebook subset restriction information for multicell communication in addition to the codebook subset restriction information for single cell communication. In this example, a codebook subset shared by single cell communication and multicell communication is used. Further, the primary base station 101 can explicitly notify (explicitly) switching information specifying either the notified single cell communication codebook subset restriction information or the multicell communication codebook subset restriction information. it can.

  FIG. 14 is a diagram showing an example of a control information notification procedure according to the second embodiment of the present invention. The primary base station 101 notifies the terminal 103 of the codebook subset restriction information for single cell communication and the codebook subset restriction information for multicell communication. Further, the primary base station 101 notifies the terminal 103 of switching information for the codebook subset restriction information. This switching information is information for designating codebook subset restriction information used by the terminal 103. Based on the restriction information and the switching information, terminal 103 can select a codebook subset or multicell communication that can be selected as a PMI for single cell communication from a predefined single cell communication / multicell communication shared codebook subset. Set a selectable codebook subset as PMI for. The primary base station 101 transmits a first transmission path condition measurement reference signal, and the secondary base station 102 transmits a second transmission path condition measurement reference signal. The terminal 103 measures each transmission path condition using the reference signal for transmission path condition measurement, and selects PMI or multicell communication suitable for single cell communication from among the codebook subsets that can be selected as the set PMI. A PMI suitable for each is selected. The terminal 103 notifies the selected PMI suitable for single cell communication or PMI suitable for multicell communication. The primary base station 101 schedules data transmission to the terminal 103 based on the notified PMI.

  By using the method described above, the primary base station 101 can feed back PMI suitable for single cell communication or PMI suitable for multicell communication without increasing the overhead of feedback information from the terminal 103. Since efficient scheduling can be performed, transmission characteristics can be improved. Further, it is not necessary to define a code book subset for single cell communication and a code book subset for multi cell communication, respectively, and optimization for precoding processing of single cell communication and multi cell communication can be realized.

  In another example in the second embodiment of the present invention, the primary base station 101 can also notify the codebook subset restriction information for multicell communication in addition to the codebook subset restriction information for single cell communication. In this example, a codebook subset shared by single cell communication and multicell communication is used. Further, the primary base station 101 implicitly specifies (implicitly) one of the notified codebook subset restriction information for single cell communication and codebook subset restriction information for multicell communication by associating with other control information. can do.

  FIG. 15 is a diagram illustrating an example of a control information notification procedure according to the second embodiment of the present invention. The primary base station 101 notifies the terminal 103 of the codebook subset restriction information for single cell communication and the codebook subset restriction information for multicell communication. Further, the primary base station 101 notifies the terminal 103 of the feedback mode. At this time, the codebook subset restriction information to be used is defined in advance corresponding to the feedback mode. For example, when the feedback mode suitable for single cell communication is notified, the terminal 103 uses the codebook subset restriction information for single cell communication. Further, when a feedback mode suitable for multi-cell communication is notified, terminal 103 uses multi-cell communication codebook subset restriction information. That is, by associating with other control information, either the notified single cell communication codebook subset restriction information or the multicell communication codebook subset restriction information can be designated. Based on the restriction information and the designated codebook subset restriction information, terminal 103 can select a code that can be selected as a PMI for single-cell communication from a predefined single-cell communication / multi-cell communication shared codebook subset. Set a selectable codebook subset as a book subset or PMI for multi-cell communication. The primary base station 101 transmits a first transmission path condition measurement reference signal, and the secondary base station 102 transmits a second transmission path condition measurement reference signal. The terminal 103 measures each transmission path condition using the reference signal for transmission path condition measurement, and selects PMI or multicell communication suitable for single cell communication from among the codebook subsets that can be selected as the set PMI. A PMI suitable for each is selected. The terminal 103 notifies the selected PMI suitable for single cell communication or PMI suitable for multicell communication. The primary base station 101 schedules data transmission to the terminal 103 based on the notified PMI.

  The control information associated with the codebook subset restriction information used by the terminal 103 can use not only the feedback mode but also transmission mode, transmission power control information, retransmission control information, adaptive modulation information, and the like. Further, the codebook subset restriction information used by the terminal 103 is included in the terminal category information (UE category) and the terminal capability information (UE capability) of the terminal 103 as well as being associated with the control information notified by the primary base station 101. It can also be associated with control information, base station (cell) control information and type (attribute, state).

  By using the method described above, the primary base station 101 can feed back PMI suitable for single cell communication or PMI suitable for multicell communication without increasing the overhead of feedback information from the terminal 103. Since efficient scheduling can be performed, transmission characteristics can be improved. Further, it is not necessary to define a code book subset for single cell communication and a code book subset for multi cell communication, respectively, and optimization for precoding processing of single cell communication and multi cell communication can be realized.

  In another example in the second embodiment of the present invention, the primary base station 101 can also notify the codebook subset restriction information for multicell communication in addition to the codebook subset restriction information for single cell communication. In this example, a codebook subset shared by single cell communication and multicell communication is used. Further, primary base station 101 can notify identification information for specifying a subframe using codebook subset restriction information for single cell communication and identification information for specifying a subframe using codebook subset restriction information for multicell communication. .

  FIG. 16 is a diagram illustrating an example of measurement subframe identification information according to the second embodiment of the present invention. The measurement subframe identification information is control information for designating a subframe using the codebook subset restriction information. Specifically, the measurement subframe identification information is information in a bitmap format in which one bit corresponds to each subframe. That is, when the measurement subframe identification information is “1”, it indicates that the corresponding codebook subset restriction information is used in the subframe. Further, when the measurement subframe identification information is “0”, it indicates that the corresponding codebook subset restriction information cannot be used in the subframe. FIG. 16 shows measurement subframe identification information for single cell communication and measurement subframe identification information for multicell communication for subframe indexes 0 to 9, respectively. That is, the codebook subset restriction information for single cell communication is used when the subframe index is 0, 3, or 7. The codebook subset restriction information for multicell communication is used when the subframe index is 2, 4, 5, or 9. In this example, the measurement subframe identification information is repeatedly applied in units of 10 subframes. Note that only one type of measurement subframe identification information may be set, and the identification information may designate either single cell communication codebook subset restriction information or multicell communication codebook subset restriction information.

  FIG. 17 is a diagram illustrating an example of a control information notification procedure according to the second embodiment of the present invention. The primary base station 101 notifies the terminal 103 of the codebook subset restriction information for single cell communication and the codebook subset restriction information for multicell communication. Further, primary base station 101 notifies terminal 103 of measurement subframe identification information for single cell communication and measurement subframe identification information for multicell communication. Terminal 103 can be selected as a PMI for single cell communication from a predefined single cell communication / multicell communication shared codebook subset based on the restriction information and the subframe index corresponding to the identification information. A selectable codebook subset or a codebook subset that can be selected as a PMI for multi-cell communication. Here, the corresponding subframe may be a subframe in which terminal 103 is instructed to feed back to primary base station 101. Also, the corresponding subframe may be a subframe that the terminal 103 feeds back to the primary base station 101. The corresponding subframe may be a subframe including the first transmission path condition measurement reference signal transmitted from the primary base station 101 and the second transmission path condition measurement reference signal transmitted from the secondary base station 102. Good. The primary base station 101 transmits a first transmission path condition measurement reference signal, and the secondary base station 102 transmits a second transmission path condition measurement reference signal. The terminal 103 measures each transmission path condition using the reference signal for transmission path condition measurement, and selects PMI or multicell communication suitable for single cell communication from among the codebook subsets that can be selected as the set PMI. A PMI suitable for each is selected. The terminal 103 notifies the selected PMI suitable for single cell communication or PMI suitable for multicell communication. The primary base station 101 schedules data transmission to the terminal 103 based on the notified PMI.

  By using the method described above, the primary base station 101 can feed back PMI suitable for single cell communication or PMI suitable for multicell communication without increasing the overhead of feedback information from the terminal 103. Since efficient scheduling can be performed, transmission characteristics can be improved. Further, it is not necessary to define a code book subset for single cell communication and a code book subset for multi cell communication, respectively, and optimization for precoding processing of single cell communication and multi cell communication can be realized.

  In the example described above, the codebook subset restriction information for single cell communication and the codebook subset restriction information for multicell communication are notified and applied to a predefined single cell communication / multicell communication shared codebook subset. However, the present invention is not limited to this. For example, a codebook subset for single cell communication and a codebook subset for multicell communication may be defined in advance, and single cell communication / multicell communication shared codebook subset restriction information may be notified and applied.

  By using such a method, the primary base station 101 can feed back PMI suitable for single cell communication or PMI suitable for multicell communication without increasing the overhead of feedback information from the terminal 103, Since efficient scheduling can be performed, transmission characteristics can be improved. In addition, since the codebook subset restriction information for single cell communication and the codebook subset restriction information for multicell communication are shared, optimization to single cell communication and multicell communication precoding processing can be performed without increasing the overhead of control information. realizable.

  In the example described above, the codebook subset restriction information for single cell communication and the codebook subset restriction information for multicell communication are notified and applied to a predefined single cell communication / multicell communication shared codebook subset. However, the present invention is not limited to this. For example, the primary base station codebook subset restriction information and the secondary base station codebook subset restriction information may be notified and applied to a primary base station / secondary base station shared codebook subset defined in advance.

  By using such a method, the primary base station 101 can feed back PMI suitable for the primary base station or PMI suitable for the secondary base station without increasing the overhead of feedback information from the terminal 103. Since efficient scheduling can be performed, transmission characteristics can be improved. In addition, it is not necessary to define a codebook subset for the primary base station and a codebook subset for the secondary base station, respectively, and the primary base station and the secondary base station can be optimized for precoding processing.

  In the example described above, the codebook subset restriction information for single cell communication and the codebook subset restriction information for multicell communication are notified and applied to a predefined single cell communication / multicell communication shared codebook subset. However, the present invention is not limited to this. For example, a primary base station codebook subset and a secondary base station codebook subset may be defined in advance, and primary base station / secondary base station shared codebook subset restriction information may be notified and applied.

  By using such a method, the primary base station 101 can feed back PMI suitable for the primary base station or PMI suitable for the secondary base station without increasing the overhead of feedback information from the terminal 103. Since efficient scheduling can be performed, transmission characteristics can be improved. In addition, since code base subset restriction information for primary base stations and code book subset restriction information for secondary base stations are shared, it is optimal for precoding processing of primary base stations and secondary base stations without increasing the overhead of control information. Can be realized.

(Third embodiment)
In the first embodiment, a case has been described in which part or all of the applied codebook subset can be restricted by using the codebook subset restriction information. In the third embodiment of the present invention, a method for controlling the probability of selecting as a PMI for a part or all of the applied codebook subset using the codebook subset power offset information is described.

  In the third embodiment of the present invention, the primary base station 101 notifies the terminal 103 of codebook subset power offset information as part of the control information.

  FIG. 18 is a diagram illustrating an example of codebook subset power offset information according to the third embodiment of the present invention. In FIG. 18, the codebook subset power offset information represents four types of power offset values by 2 bits. The primary base station 101 can set a power offset value for each codebook with respect to the terminal 103, and can control the probability that the terminal 103 selects as the PMI for each codebook. For example, when increasing the selection probability of a target codebook, the primary base station 101 sets a high power offset value for the codebook. Also, when lowering the selection probability of the target codebook, the primary base station 101 sets a power offset value for that codebook low. Further, when the target codebook is not selected, the primary base station 101 sets the power offset value for the codebook to the minimum.

  FIG. 19 is a schematic block diagram showing the configuration of the feedback information generation unit 404 according to the third embodiment of the present invention. In FIG. 19, the feedback information generation unit 404 includes a transmission path condition measurement unit 1901 and a feedback information calculation unit 1902.

  The transmission path condition measurement unit 1901 measures the transmission path condition of the transmission antenna in each base station with respect to the reception antenna at the terminal 103 for each base station using the received transmission path condition measurement reference signal, and transmits the transmission for each base station. Generate road condition measurements. Next, feedback information calculation section 1902 calculates feedback information based on the generated transmission path condition estimated value. At this time, the feedback information calculation unit 1902 also receives codebook subset power offset information included in the control information signal and the like, and takes it into account when calculating feedback information.

  When performing an operation on a target code book, the feedback information calculation unit 1902 performs power offset control on the transmission path state estimated value measured by the transmission path state measurement unit using the power offset value for the code book. For example, when the power offset value is 3 dB, the power of the transmission path state measurement value after the offset is increased by 3 dB. When the power offset value is −3 dB, the power of the transmission path state measurement value after the offset is reduced by 3 dB. When the power offset value is 0 (true value), the power of the transmission path state measurement value after the offset is 0, and the codebook is not selected.

  By using the method of the third embodiment of the present invention, the primary base station 101 controls the probability that the terminal 103 will select part or all of the codebook subset to be applied as the PMI. Can do. Therefore, the primary base station 101 can increase the degree of freedom of scheduling for the terminal 103, and thus can improve the transmission efficiency.

  Note that the method of the third embodiment of the present invention, as described in the first and second embodiments of the present invention, includes a plurality of codebook subsets, that is, codes for single cell communication / multi-cell communication. The present invention can be similarly applied to the case where there is a book subset and a codebook subset for primary base station / secondary base station.

  The code book subset power offset information is information set for each code book, but may be information set for a group of a plurality of code books. Specifically, the code book subset power offset information may be information set for a group of a part or all of the code book for each rank. For example, W10 and W12 described in FIG. 8 can be grouped, and W11 and W13 can be grouped. Further, the code book subset power offset information may be information that is set for a group of a part or all of the code book for each code book index over a plurality of ranks. For example, W11 and W21 described in FIG. 8 can be grouped, and W12 and W22 can be grouped. As described above, by grouping a plurality of codebooks, the overhead of the codebook subset power offset information can be reduced.

  In each of the above embodiments, the case where the primary base station 101 and the secondary base station 102 perform communication in cooperation has been described. Of course, the base station mentioned here may be a physical base station apparatus in a cellular system, but in addition to this, a set of transmitting apparatuses (including relay apparatuses) that cooperate while extending cells. (A first transmitter and a second transmitter), or a set of transmitters that cooperate while transmitting reference signals for transmission path status measurement using different antenna ports (a first port and a second port). For example, the primary base station 101 and the secondary base station 102 can be used, and the same effects as those of the above embodiments can be obtained. For example, the primary base station 101 is a base station apparatus in a cellular system, and the secondary base station 101 is a transmission apparatus controlled by the primary base station 102 (for example, RRU (Remote Radio Unit), RRE (Remote Radio Equipment), Distributed). or the secondary base station 102 is a base station apparatus in the cellular system, and the primary base station 101 can be a transmitting apparatus controlled and operated by the secondary base station 102. Alternatively, both the primary base station 101 and the secondary base station 102 may be transmitting apparatuses that are controlled and operated by a physical base station apparatus in a cellular system.

In each of the above embodiments, the cooperative communication between the primary base station 101 and the secondary base station 102 has been described mainly in the case where the secondary base station 102 is adjacent to the primary base station 101, but the present invention is not limited to this. For example, even when the communication area of the primary base station 101 and the communication area of the secondary base station 102 overlap all or partly as in a heterogeneous network, the same effects described in the above embodiments can be obtained. . At that time, all or part of the component carriers (carrier frequencies) of the respective base stations may overlap. Specifically, the primary base station 101 is a macro cell, and the secondary base station 102 is a pico cell or femto cell (Home).
Even when a communication area smaller than the communication area of the macro cell such as eNodeB) overlaps with the communication area of the primary base station 101, the present invention can be applied.

  In each of the above embodiments, resource elements and resource blocks are used as mapping units for information data signals, control information signals, PDSCH, PDCCH, and reference signals, and subframes and radio frames are used as transmission units in the time direction. However, it is not limited to this. The same effect can be obtained even if a region and a time unit composed of an arbitrary frequency and time are used instead. In each of the above embodiments, the case of demodulating using a precoded RS is described, and the port corresponding to the precoded RS is described using a port equivalent to the MIMO layer. However, it is not limited to this. In addition, the same effect can be obtained by applying the present invention to ports corresponding to different reference signals. For example, Unprecoded RS is used instead of Precoded RS, and a port equivalent to an output end after precoding processing or a port equivalent to a physical antenna (or a combination of physical antennas) can be used as a port.

  A program that operates in the primary base station 101, the secondary base station 102, and the terminal 103 according to the present invention is a program that controls a CPU or the like (a program that causes a computer to function) so as to realize the functions of the above-described embodiments according to the present invention. It is. Information handled by these devices is temporarily stored in the RAM at the time of processing, then stored in various ROMs and HDDs, read out by the CPU, and corrected and written as necessary. As a recording medium for storing the program, a semiconductor medium (for example, ROM, nonvolatile memory card, etc.), an optical recording medium (for example, DVD, MO, MD, CD, BD, etc.), a magnetic recording medium (for example, magnetic tape, Any of a flexible disk etc. may be sufficient. In addition, by executing the loaded program, not only the functions of the above-described embodiment are realized, but also based on the instructions of the program, the processing is performed in cooperation with the operating system or other application programs. The functions of the invention may be realized.

  In the case of distribution in the market, the program can be stored and distributed in a portable recording medium, or transferred to a server computer connected via a network such as the Internet. In this case, the storage device of the server computer is also included in the present invention. Further, some or all of the primary base station 101, the secondary base station 102, and the terminal 103 in the above-described embodiment may be realized as an LSI that is typically an integrated circuit. Each functional block of the primary base station 101, the secondary base station 102, and the terminal 103 may be individually chipped, or a part or all of them may be integrated into a chip. Further, the method of circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. In addition, when an integrated circuit technology that replaces LSI appears due to progress in semiconductor technology, an integrated circuit based on the technology can also be used.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like without departing from the gist of the present invention. The present invention can be modified in various ways within the scope of the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present invention. It is. Moreover, it is the element described in each said embodiment, and the structure which substituted the element which has the same effect is also contained.

  The present invention is suitable for use in a radio base station apparatus, a radio terminal apparatus, a radio communication system, and a radio communication method.

101 Primary base station 102 Secondary base station 103 Terminal 104, 105 Downlink 106 Uplink 201, 301 Transmission signal generator 202 First transmission path condition measurement reference signal multiplexer 203, 303, 405 Transmitter 204, 401 Receiver 205 Feedback information processing units 206, 304, 406 Upper layer 302 Second transmission path state measurement reference signal multiplexing unit 402 Reception signal processing unit 403 Data signal processing unit 404 Feedback information generation units 501, 1301, 1901 Transmission path state measurement unit 502, 1302, 1902 Feedback information calculation unit 1303 Selection unit 2001 Base station 2002 Terminal 2003 Downlink 2004 Uplink

Claims (12)

A base station device that communicates with a terminal device,
An upper layer that sets first codebook subset restriction information and second codebook subset restriction information indicating precoding weights that are not permitted as a precoding matrix index report in the terminal device;
A receiving unit that receives the first transmission path condition information report based on the first codebook subset restriction information or the second transmission path condition information report based on the second codebook subset restriction information ;
The first codebook subset restriction information and the second codebook subset restriction information are associated with the same codebook subset;
The first channel-state information reports and the second channel state information reporting base station and wherein the independent der Rukoto one another. The first transmission path status information report is a report based on a first transmission path status measurement reference signal, and the second transmission path status information report is a report based on a second transmission path status measurement reference signal. Oh it is,
The base station apparatus according to claim 1, characterized in Rukoto set to each of the first channel-state reference signal and the second channel-state information reference signal measurement for the determination of the independent.   The first transmission path status information report is a report based on first measurement subframe identification information, and the second transmission path status information report is a report based on second measurement subframe identification information. The base station apparatus according to claim 1.   The said receiving part receives the said 1st transmission path condition information report or the said 2nd transmission path condition information report based on the control information notified to the said terminal device, The Claim 1 characterized by the above-mentioned. Base station device. A terminal device that communicates with a base station device,
An upper layer in which first codebook subset restriction information and second codebook subset restriction information indicating precoding weights that are not permitted as a report of the precoding matrix index are set;
A transmission unit that transmits a first transmission path condition information report based on the first codebook subset restriction information or a second transmission path condition information report based on the second codebook subset restriction information ;
The first codebook subset restriction information and the second codebook subset restriction information are associated with the same codebook subset;
The first channel-state information reports and the second channel state information report terminal device according to claim independent der Rukoto one another. The first transmission path status information report is a report based on a first transmission path status measurement reference signal, and the second transmission path status information report is a report based on a second transmission path status measurement reference signal. Oh it is,
Terminal device according to claim 5, characterized in Rukoto set to each of the first channel-state reference signal and the second channel-state information reference signal measurement for the determination of the independent.   The first transmission path status information report is a report based on first measurement subframe identification information, and the second transmission path status information report is a report based on second measurement subframe identification information. The terminal device according to claim 5.   6. The transmission unit according to claim 5, wherein the transmission unit transmits the first transmission path status information report or the second transmission path status information report based on control information notified from the base station apparatus. The terminal device described. A communication method used in a base station device that communicates with a terminal device,
Setting first codebook subset restriction information and second codebook subset restriction information indicating precoding weights not permitted as a precoding matrix index report in the terminal device;
The first channel-state information report based on the first codebook subset restriction information, or have a receiving a second channel-state information report based on the second codebook subset restriction information,
The first codebook subset restriction information and the second codebook subset restriction information are associated with the same codebook subset;
The first channel-state information reports and the second channel state information report communication method characterized by independent der Rukoto one another. A communication method used in a terminal device that communicates with a base station device,
Setting first codebook subset restriction information and second codebook subset restriction information indicating precoding weights that are not allowed as a precoding matrix index report;
The first channel-state information report based on the first codebook subset restriction information, or have a transmitting a second channel state information report based on the second codebook subset restriction information,
The first codebook subset restriction information and the second codebook subset restriction information are associated with the same codebook subset;
The first channel-state information reports and the second channel state information report communication method characterized by independent der Rukoto one another. An integrated circuit realized by a base station device that communicates with a terminal device,
A function of setting, in the terminal device, first codebook subset restriction information and second codebook subset restriction information indicating precoding weights that are not permitted as a precoding matrix index report;
The first channel-state information report based on the first codebook subset restriction information, or possess a function to receive a second channel-state information report based on the second codebook subset restriction information,
The first codebook subset restriction information and the second codebook subset restriction information are associated with the same codebook subset;
The first channel-state information reports and the second channel state information report is characterized independence der Rukoto one another integrated circuit. An integrated circuit realized by a terminal device that communicates with a base station device,
A function in which first codebook subset restriction information and second codebook subset restriction information indicating precoding weights that are not permitted as a report of the precoding matrix index are set;
The first channel-state information report based on the first codebook subset restriction information, or possess a function of transmitting a second channel state information report based on the second codebook subset restriction information,
The first codebook subset restriction information and the second codebook subset restriction information are associated with the same codebook subset;
The first channel-state information reports and the second channel state information report is characterized independence der Rukoto one another integrated circuit.