JP2013106248A - Communication system, communication method, base station device, and mobile station device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication system, communication method, base station device, and mobile station device that can improve frequency efficiency even if inter-cell interference occurs between cells of a plurality of base station devices.SOLUTION: In a communication system 1 in which each cell of a plurality of base station devices 100-j is arranged such that all or part of the cell will overlap with another cell, a master base station device 100-1 calculates a transmission weighting coefficient Vof each base station device 100-j and a reception weighting coefficient Uof a mobile station device 200-k such that the direction of an equivalent propagation path of an interference signal received by the mobile station device 200-k connected to each base station device 100-j will be orthogonal to the reception weighting coefficient by which the mobile station device 200-k multiplies the reception signal. The base station device 100-j notifies the mobile station device 200-k connected to the own station of the reception weighting coefficient U, and the mobile station device 200-k performs reception processing by multiplying the reception signal including the interference signal by the reception weighting coefficient U.

Description

  The present invention relates to a communication system, a communication method, a base station apparatus, and a mobile station apparatus.

  In a wireless communication system such as a mobile phone, a base configuring a cell (communication service area) for providing a wireless communication service to a plurality of mobile station devices (terminals: UE (User Equipment)) in a city and its surrounding area A station apparatus (eNB; eNodeB) is arranged. In particular, in a wireless communication system, a cellular configuration in which a plurality of base station devices are arranged is formed, and the communication area is expanded.

  In recent years, with the rapid urbanization, high-rise buildings, condominiums, and the like are constructed, and many reception insensitive areas or weak electric field areas are generated. In these areas, the connection between the mobile station device and the base station device is often restricted. In addition, with an increase in the speed of mobile communication systems, an improvement in throughput for mobile stations is required. Similarly, it is required that a mobile station apparatus existing at the cell edge (end area of the communication service area) can perform high-speed communication without any problem.

  As a method of improving the throughput, a part or all of the range of the macro cell formed by the main base station apparatus (macro base station), and a low power base station (pico cell base station, femto cell base having a maximum transmission power smaller than that of the macro base station) It has been proposed to arrange a plurality of base station apparatuses so as to overlap the cell range of a station etc. (heterogeneous network, Non-Patent Document 1).

  FIG. 18 shows an outline of a radio communication system 1000 in the downlink in which a plurality of base station apparatuses having different cell radii are arranged. Cell 1000-1a (macro cell) of main base station apparatus 1000-1 (macro base station apparatus) and cell 1000-2a of base station apparatus 1000-2 which is a low power base station having a maximum transmission power smaller than that of the macro base station apparatus Each base station apparatus is arranged with one-cell frequency repetition so that (picocell) and cell 1000-3a (picocell) of base station apparatus 1000-3 overlap. A plurality of mobile station apparatuses exist in the cell, and each mobile station apparatus is controlled to be wirelessly connected to a base station apparatus that can receive a signal with the maximum received electric field strength. In FIG. 18, the mobile station device 2000-1 is wirelessly connected (r11) to the base station device 1000-1, the mobile station device 2000-2 is wirelessly connected (r22) to the base station device 1000-2, and the mobile station The device 2000-3 performs wireless connection (r33) with the base station device 1000-3.

  By constructing such a heterogeneous network (heterogeneous network), it is possible to improve the total frequency utilization efficiency seen from the network side in the area covered by the macro cell.

  Further, as a method for suppressing and reducing inter-cell interference in the downlink of a heterogeneous network, a method of performing communication by transmitting a signal to a mobile station device in cooperation between a plurality of base station devices is disclosed (non-contained) Patent Document 2).

  FIG. 19 shows a transmission frame format in the downlink of the heterogeneous network. In the upper part of FIG. 19, one frame includes 10 types of subframes including a normal subframe and a resource mapping limited subframe (also referred to as a limited subframe). In the upper part of FIG. 19, subframe index # 1, subframe index # 3, subframe index # 4, subframe index # 5, and subframe index # 9 are normal subframes, subframe index # 0, and subframe. Index # 2, subframe index # 6, subframe index # 7, and subframe index # 8 are resource mapping limited subframes. The resource mapping limited subframe corresponds to ABS (Almost Blank Subframe), MBSFN (Multicast / Broadcast over Single Frequency Network), or the like.

  The normal subframe is a subframe in which the base station apparatus can perform resource mapping of information data, control data, and a reference signal. For example, as a downlink signal in LTE, a downlink common channel (PDSCH; Physical Downlink Shared Channel, a channel that mainly transmits information data), a downlink control channel (PDCCH; Physical Downlink Control Channel, horizontal stripe portion in the figure) , A synchronization signal (PSS; Primary Synchronization Signal, SSS; Secondary Synchronization Signal), a broadcast channel (PBCH; Physical Broadcast Channel), a cell-specific reference signal (CRS; Cell-Recec), and a cell-specific reference signal (CRS; Cell-Recec).

  The resource mapping restriction subframe is a subframe in which the base station apparatus restricts resource mapping to only a predetermined signal. In the ABS, only CRS and / or predetermined control signals (SSS, PSS, PBCH (lattice portion in the figure), etc.) are arranged (subframe index # 0 in the upper part of FIG. 19). In the MBSFN subframe, only the CRS is arranged (subframe index # 2, subframe index # 6, subframe index # 7, and subframe index # 8 in the upper part of FIG. 19). In the ABS and MBSFN subframes, signals other than the above-described signals (for example, PDSCH) are not allocated (shaded portion in the figure).

  The lower part of FIG. 19 shows a downlink transmission frame format when a signal is transmitted to the mobile station apparatus to which the base station apparatus 1000-2 and the base station apparatus 1000-3 are connected. In the lower part of FIG. 19, one frame is composed of 10 normal subframes. 19, information data (PDSCH) transmitted from the base station apparatus 1000-1 to the mobile station apparatus 2000-1 includes subframe index # 0, subframe index # 2, subframe index # 6, Arranged in subframes other than subframe index # 7 and subframe index # 8. The information data transmitted from the base station apparatus 1000-2 to the mobile station apparatus 2000-2 includes subframe index # 0, subframe index # 4, subframe index # 5, subframe index # 6, and subframe in the lower part of FIG. Arranged at frame index # 8. Information data transmitted from the base station apparatus 1000-3 to the mobile station apparatus 2000-3 includes subframe index # 0, subframe index # 4, subframe index # 5, subframe index # 6, and subframe in the lower part of FIG. Arranged at frame index # 8.

  Thus, base station apparatus 1000-2 and base station apparatus 1000-3 cause inter-cell interference from base station apparatus 1000-1 in a subframe synchronized with a subframe in which base station apparatus 1000-1 does not place information data. Inter-cell interference from base station apparatus 1001-1 can be reduced because information data of receiving mobile station apparatus 2000-2 and mobile station apparatus 200-4 are allocated.

3rd Generation Partnership Project; Technical Specification Group Radio Access Network; 3rd Generation Advances for E-UTRA Physical Layer. (2010-03) URL: http://www.3gpp.org/ftp/Specs/html-info/36814.htm R1-105442, 3GPP TSG RAN WG1 Meeting # 62bis

  However, in Non-Patent Document 1, when the base station device 1000-1 is transmitting a signal, the mobile station device 2000-2 connected to the pico cell 1000-2a and the mobile station connected to the pico cell 1000-3a. As illustrated in FIG. 18, the device 2000-3 has a problem that transmission efficiency is reduced by receiving interference (inter-cell interference) (r12) and (r13) from the macro cell 1000-1a. is there.

  In addition, in the method for suppressing and reducing inter-cell interference described in Non-Patent Document 2, when inter-cell interference occurs between pico cells, the SINR of the mobile station apparatuses 2000-2 and 2000-3 decreases. . In FIG. 18, the interference (r32) from the base station apparatus 1000-3 to the mobile station apparatus 2000-2 and the interference (r23) from the base station apparatus 1000-2 to the mobile station apparatus 2000-3 are the causes of the SINR reduction. Become. For this reason, there is a problem that even if a heterogeneous network is constructed, the frequency utilization efficiency cannot be sufficiently improved.

  The present invention has been made in view of the above circumstances, and a communication system, a communication method, a base station apparatus, and a mobile station that can improve frequency efficiency even when inter-cell interference occurs between cells of a plurality of base station apparatuses. The object is to provide an apparatus.

  In order to solve the above-described problem, each configuration of a communication system, a communication method, a base station apparatus, and a mobile station apparatus according to the present invention is as follows.

  The communication system of the present invention includes a plurality of base station apparatuses and a mobile station apparatus connected to at least one of the plurality of base station apparatuses, and the plurality of base station apparatuses can connect each base station apparatus. The communication system is arranged such that the entire range or a part of the range overlaps each other, and the base station device instructs the mobile station device to receive a weighting coefficient to be multiplied by the received signal received by the mobile station device. Information on the weighting factor to be notified is notified.

  The plurality of base station apparatuses of the communication system according to the present invention include a plurality of base station apparatuses including a master base station apparatus and a slave base station apparatus, and the master base station apparatus includes propagation path information of the entire system. A transmission weighting factor to be multiplied for transmission data transmitted by the plurality of base station devices using a reception signal to be multiplied to a reception signal received by the mobile station device to which each of the plurality of base station devices is connected. A plurality of base station apparatuses that generate a precoding unit that multiplies the transmission data by the transmission weight coefficient, and weight coefficient information that indicates the reception weight coefficient. A weighting factor information generation unit, and information data obtained by multiplying the transmission data by the transmission weighting factor and the weighting factor information are transmitted to the mobile station device to which each of the plurality of base station devices is connected. The mobile station apparatus includes a control signal detector that detects a reception weight coefficient from the weight coefficient information, and interference suppression that multiplies the reception signal by the reception weight coefficient to obtain the information data. It is characterized by providing a part.

  In the communication system of the present invention, the weighting factor information is a control signal including a reception weighting factor for multiplying a reception signal received by each mobile station device connected by the base station device. It is what. The weighting factor information is a control signal including a codebook index corresponding to the transmission weighting factor of the plurality of base station devices and the reception weighting factor of the mobile station device. The weighting factor information is a reference signal multiplied by the reception weighting factor.

  The reference signal of the communication system according to the present invention is a part of a reference signal unique to the mobile station apparatus. The reference signal is a part of a reference signal unique to the cell of the base station apparatus. The reference signal is a reference signal specific to the mobile station apparatus or a reference signal specific to a cell of the base station apparatus.

  In the communication system of the present invention, the master base station device includes an upper layer that notifies the slave base station device of information related to the transmission weighting factor and information related to the reception weighting factor, and the slave base station device further includes: A weighting factor information generating unit that generates weighting factor information including information on the receiving weighting factor notified from the higher layer is provided.

The communication method of the present invention includes a plurality of base station devices and a mobile station device connected to at least one of the plurality of base station devices, and the plurality of base station devices are connected to each base station device. A communication method in a communication system arranged such that all or part of the connectable range overlap each other, wherein the base station device multiplies the mobile station device by a received signal received by the mobile station device A step of notifying reception weight coefficient information indicating the reception weight coefficient is performed.

  The base station apparatus of the present invention includes a plurality of base station apparatuses including a main base station apparatus and a slave base station apparatus, and a mobile station apparatus connected to at least one of the plurality of base station apparatuses. The base station apparatus in a communication system in which the plurality of base station apparatuses are arranged such that all or part of the connectable range of each base station apparatus overlaps each other, and the main base station apparatus A transmission weight coefficient that is multiplied by transmission data transmitted by the plurality of base station apparatuses using propagation path information, and a reception signal received by the mobile station apparatus to which each of the plurality of base station apparatuses is connected. A weight coefficient control unit that calculates a reception weight coefficient to be multiplied, and the plurality of base station apparatuses receive a precoding unit that multiplies the transmission data by the transmission weight coefficient, and a reception instruction that indicates the reception weight coefficient The mobile station to which each of the plurality of base station devices is connected to a weighting coefficient information generating unit that generates only coefficient information, information data obtained by multiplying the transmission data by the transmission weighting coefficient, and the reception weighting coefficient information A transmission unit for transmitting to the apparatus is provided.

The mobile station apparatus of the present invention includes a plurality of base station apparatuses including a main base station apparatus and a slave base station apparatus, and a mobile station apparatus connected to at least one of the plurality of base station apparatuses. The base station apparatus is a mobile station apparatus in a communication system arranged such that all or part of the connectable range of each base station apparatus overlaps each other, wherein the mobile station apparatus is the main base station A reception unit that receives a reception signal obtained by multiplying a transmission weighting factor calculated by the apparatus using propagation path information of the entire system and reception weighting factor information, and a control signal detection unit that detects a reception weighting factor from the reception weighting factor information And an interference suppression unit that obtains the information data by multiplying the reception signal by the reception weight coefficient.

  According to the present invention, in a communication system including a plurality of base station devices and a mobile station device connected to at least one of the plurality of base station devices, the plurality of base station devices use the same frequency. When communicating with a mobile station apparatus, a plurality of base station apparatuses and mobile station apparatuses can cooperate to suppress inter-cell interference. For this reason, the said communication system can show | play the outstanding effect that the interference between cells can be suppressed effectively and favorable transmission / reception can be established.

It is the schematic which shows the structure of the communication system which concerns on 1st Embodiment. It is the schematic which shows the structure of the main base station apparatus of the communication system which concerns on 1st Embodiment. It is an example of the format which the control signal generation part of the main base station apparatus of the communication system which concerns on 1st Embodiment outputs. It is a flowchart which shows the process which calculates a transmission weight coefficient and a reception weight coefficient in the main base station of the communication system which concerns on 1st Embodiment. It is the schematic which shows the structure of the slave base station apparatus of the communication system which concerns on 1st Embodiment. It is the schematic which shows the structure of the mobile station apparatus of the communication system which concerns on 1st Embodiment. It is a sequence diagram which shows the process which the main base station apparatus of the communication system which concerns on 1st Embodiment calculates a transmission weight coefficient and a reception weight coefficient, and notifies to a subordinate base station apparatus and a mobile station apparatus. It is an example of the code book in the communication system which concerns on 2nd Embodiment. It is an example of the format which the control signal generation part of the main base station apparatus of the communication system which concerns on 2nd Embodiment outputs. It is the schematic which shows the structure of the communication system which concerns on 3rd Embodiment. It is the schematic which shows the structure of the main base station apparatus of the communication system which concerns on 3rd Embodiment. It is the schematic which shows the structure of the slave base station apparatus which concerns on 3rd Embodiment. It is the schematic which shows the structure of the mobile station apparatus which concerns on 3rd Embodiment. It is an example of the resource mapping in the resource mapping part of the base station apparatus which concerns on 3rd Embodiment. It is another example of the resource mapping in the resource mapping part of the base station apparatus which concerns on 3rd Embodiment. It is another example of the resource mapping in the resource mapping part of the base station apparatus which concerns on 3rd Embodiment. It is another example of the resource mapping in the resource mapping part of the base station apparatus which concerns on 3rd Embodiment. It is the schematic which shows the structure of the conventional communication system. It is the transmission frame format in the downlink of the conventional heterogeneous network.

<First Embodiment>
In the communication system 1 according to the first embodiment, an example in which the base station apparatus 100-j and the mobile station apparatus 200-k perform data transmission using an OFDM (Orthogonal Frequency Division Multiplexing) scheme. explain. The present embodiment is not limited to this, but other transmission schemes, for example, SC-FDMA (single carrier-frequency division multiple access; single carrier frequency division multiple access), DFT-s-OFDM (discrete Fourier transform-spread). A single carrier transmission scheme such as OFDM (Discrete Fourier Transform Spread OFDM) or a multicarrier transmission scheme such as MC-CDMA (Multiple Carrier-Code Division Multiple Access) may be used. In addition, as examples of the communication system 1 according to the first embodiment, WCDMA (Wideband Code Division Multiple Access), LTE (Long Term Evolution), LTE-I (E), LTE-A (E), and LTE-I (E) Including, but not limited to, a wireless communication system such as WiMAX (World Wide Interoperability Access) by (The Institute of Electrical and Electronics Engineers).

  FIG. 1 is a schematic diagram showing a configuration of a communication system 1 according to the first embodiment of the present invention. The communication system 1 according to the first embodiment includes a plurality of base station devices 100-j (j is an arbitrary positive integer, j = 1 to 3 in FIG. 1), and a plurality of mobile station devices 200. −k (k is an arbitrary positive integer, and k = 1 to 3 in FIG. 1).

  The plurality of base station apparatuses 100-j in the communication system 1 are configured to suppress inter-cell interference in cooperation with each other. In addition, the mobile station device 200-k in the communication system 1 includes a mobile station device connected to a cooperating base station device and a mobile station device to be coordinated.

  Each base station apparatus 100-j is arranged in such a configuration that its own cell overlaps with the cells of other base station apparatuses in whole or in part. The base station apparatuses 100-j are connected by backhaul lines 10-1, 10-2 (for example, X2 interface) using optical fibers, Internet lines, radio lines, or the like. The communication system 1 uses so-called one-cell frequency repetition that uses the same frequency in all cells.

A _space between the base station apparatus 100-j and the mobile station apparatus 200-k is represented by each propagation path H _kj (transfer function) (k and j are arbitrary positive integers. In FIG. 3 and j = 1 to 3). Here, the propagation path H _kj between the base station apparatus and the mobile station apparatus to be coordinated is called a propagation path of the entire system. In the communication system 1, the mobile station device 200-k is wirelessly connected to the base station device 100-j where k = j. That is, in the mobile station apparatus 200-k, a signal transmitted from the base station apparatus 100-j where k ≠ j is inter-cell interference.

For example, the mobile station device 200-1, transmission signal from the base station apparatus 100-1 which receives through the channel _{H 11} is the desired signal, received through the channel _{H 12} and the channel _{H 13} base Transmission signals from the station apparatus 100-2 and the base station apparatus 100-3 become inter-cell interference (undesired signal).

As will be described in detail later, each base station apparatus 100-j can suppress inter-cell interference that the base station apparatus 100-j and the mobile station apparatus 200-k can cooperate with each other in a transmission signal transmitted by itself. The transmission weight coefficient V _j is multiplied. Also, each mobile station apparatus 200-k multiplies the received signal by a reception weight coefficient U _k that can suppress inter-cell interference that the base station apparatus 100-j and the mobile station apparatus 200-k can cooperate with each other. To do.

  Hereinafter, in the communication system 1 in FIG. 1, the base station device 100-1 is a main base station device (master base station device) that calculates a transmission weight coefficient and a reception weight coefficient, and the base station device 100-2 and the base station device. Reference numeral 100-3 denotes a slave base station device (slave base station device) that operates cooperatively according to an instruction from the master base station device.

  Next, the master base station apparatus (base station apparatus 100-1) according to the first embodiment will be described.

  As shown in FIG. 2, the master base station apparatus (base station apparatus 100-1) includes an upper layer 101, an encoding unit 102, a modulation unit 103, a precoding unit 104, a weighting coefficient control unit 105, and a reference signal generation unit 106. , Control signal generation section 107, resource mapping section 108, IDFT section 109, GI insertion section 110, transmission section 111, transmission antenna section 112, reception antenna section 121, reception section 122, and control signal detection section 123. . When a part or all of the base station device 100-1 is formed into a chip to form an integrated circuit, a chip control circuit (not shown) for controlling each functional block is provided.

  The base station device 100-1 receives a signal including a control signal such as propagation path information transmitted by the mobile station device 200-1 via the uplink via the reception antenna unit 121, and the reception unit 122 receives the control signal. Are converted to a frequency band that allows digital signal processing such as signal detection processing (radio frequency conversion), and filtering processing to remove spurious is performed, and the filtered signal is converted from an analog signal to a digital signal (Analog to (Digital conversion).

  The control signal detection unit 123 performs demodulation processing, decoding processing, and the like on the control signal output from the reception unit 122. The control signal is detected from the uplink control channel (PUCCH) and the uplink common channel (PUSCH).

Upper layer 101 includes propagation path information (propagation path information H ₁₁ between base station apparatus 100-1 and mobile station apparatus 200-1, base station apparatus 100-2, included in the control signal input from control signal detection section 123. And propagation path information H ₁₂ between mobile station apparatus 200-1 and propagation path information H ₁₃ between base station apparatus 100-3 and mobile station apparatus 200-1). Here, the upper layer is a layer of functions higher than the physical layer (physical layer) among the layers of communication functions defined in the OSI reference model, for example, a data link layer, a network layer, and the like.

Further, the upper layer 101 acquires propagation path information from the slave base station devices (base station device 100-2 and base station device 100-3) through the backhaul lines 10-1 and 10-2. Specifically, the upper layer 101, (information on the propagation path _{H 21)} channel information between the base station device 100-1 and the mobile station device 200-2, the mobile station apparatus and base station apparatus 100-2 200-2 channel information between (information about the channel _{H 22),} channel information between the mobile station apparatus 200-2 and base station apparatus 100-3 (information about the channel _{H 23)} is obtained through the backhaul 10-1 and, (information on channel _{H 31)} channel information between the base station device 100-1 mobile station apparatus 200-3, the channel information (propagation path between the mobile station apparatus 200-3 and base station apparatus 100-2 Information on H ₃₂ ) and propagation path information (information on propagation path H ₃₃ ) between the base station apparatus 100-3 and the mobile station apparatus 200-3 are acquired through the backhaul line 10-2.

  That is, the master base station apparatus estimates the propagation path fluctuations with all the base station apparatuses (master base station apparatus and slave base station apparatus) that each mobile station apparatus 200-k performs cooperative control. Get road information.

  Further, the upper layer 101 inputs the propagation path information to the weight coefficient control unit 105. Here, the upper layer 101 may be configured to input the number of base station apparatuses and the number of mobile station apparatuses to cooperate to the weight coefficient control unit 105.

The upper layer 101 notifies the slave base station apparatus of the transmission weight coefficient and the reception weight coefficient calculated by the weight coefficient control unit 105 described later via the backhaul lines 10-1 and 10-2. The upper layer of the base station device 100-1 101 includes a transmission weight factor _{V 2} of the base station device 100-2 multiplies the transmission signal, the reception weighting coefficient mobile station device 200-2 multiplies the reception signal _{U 2} To the base station apparatus 100-2 via the backhaul line 10-1. The upper layer 101 of the base station 100-1, a transmission weight factor _{V 3} to the base station device 100-3 multiplies the transmission signal, the reception weighting factors _{U 3} to the mobile station device 200-3 multiplies the reception signal To the base station apparatus 100-3 via the backhaul line 10-2.

The upper layer 101 also acquires feedback information such as MCS information and the number of spatial multiplexing included in the control signal. Upper layer 101 outputs information data to encoding section 102 and outputs control data to control signal generation section 107 based on the feedback information. The upper layer 101 also notifies other parameters necessary for each part of the base station apparatus 100-1 to exhibit its function.

  The encoding unit 102 performs error correction encoding on the information data input from the upper layer 101. The information data is, for example, an audio signal accompanying a call, a still image or moving image signal representing a captured image, a character message, or the like. The encoding method used when the encoding unit 102 performs error correction encoding is, for example, turbo encoding, convolutional encoding, low density parity check encoding; LDPC).

  The encoding unit 102 performs rate matching processing on the encoded bit sequence in order to match the coding rate of the error correction encoded data sequence with the encoding rate corresponding to the data transmission rate. May be. Further, the encoding unit 102 may have a function of rearranging and interleaving the error correction encoded data series.

  Modulation section 103 modulates the signal input from encoding section 102 to generate a modulation symbol. The modulation processing performed by the modulation unit 103 includes, for example, BPSK (binary phase shift keying; two-phase phase modulation), QPSK (quadture phase shift keying; four-phase phase modulation), and M-QAM (M-quad quadrature amplitude value; Amplitude modulation, eg M = 16, 64, 256, 1024, 4096). Modulation section 103 may have a function of rearranging generated modulation symbols and interleaving them.

ここで、Ｈ_ｋｊは、基地局装置１００−ｊと、協調制御の対象である移動局装置２００−ｋとの間の伝搬路行列、Ｖ_ｊは基地局装置１００−ｊの送信重み係数のベクトル、Ｕ_ｋは移動局装置２００−ｋの受信重み係数のベクトル、ｄ_ｋはストリーム数である。_Ｈは複素共役転置である。 The weight coefficient control unit 105 uses the propagation path information (propagation path estimated value) acquired from the upper layer 101 to multiply the signal transmitted by the master base station apparatus and the slave base station apparatus, and the transmission weight coefficient V _{j and} each base. A reception weight coefficient U _k by which the mobile station apparatus connected to the station apparatus multiplies the reception signal is calculated. That is, the weight coefficient control unit 105 calculates a transmission weight coefficient and a reception weight coefficient using the propagation path information of the entire system.
As an example, the weighting factor control section 105 is such that the direction (vector) of the equivalent propagation path of interference signals arriving from a plurality of base station devices serving as interference sources is orthogonal to the reception weighting factor by which each mobile station device multiplies the received signal. Thus, the transmission weighting coefficient is calculated (Equation 1).

Here, H _kj is a propagation path matrix between the base station apparatus 100-j and the mobile station apparatus 200-k that is the target of cooperative control, and V _j is a vector of transmission weight coefficients of the base station apparatus 100-j. , U _k is a vector of reception weight coefficients of the mobile station apparatus 200-k, and d _k is the number of streams. _H is a complex conjugate transpose.

Further, the weight coefficient control unit 105 notifies the upper layer 101 of the transmission weight coefficient V _j of the slave base station apparatus and the reception weight coefficient U _k of the mobile station apparatus connected to the slave base station apparatus.
Further, the weight coefficient control unit 105 outputs a transmission weight coefficient V ₁ to be multiplied to the transmission signal of the master base station apparatus (own station) to the precoding unit 104. Also, the weight coefficient control unit 105 outputs the reception weight coefficient U ₁ of the mobile station apparatus connected to the master base station apparatus (own station) to the control signal generation unit 107.

Precoding section 104 multiplies the modulation symbol output from modulation section 103 by transmission weight coefficient V ₁ .

  The reference signal generation unit 106 generates a reference signal (pilot signal) and outputs the generated reference signal to the resource mapping unit 108. For example, the reference signal is a signal used to estimate the propagation characteristics from the transmission antenna unit 112 of the base station device to the reception antenna units 201-1 and 201-2 of each mobile station device. The estimated propagation characteristics are used for propagation path information for calculating transmission weight coefficients and reception weight coefficients, or propagation path compensation in the mobile station apparatus. The code sequence constituting the reference signal is preferably an orthogonal sequence, for example, a Hadamard code or a CAZAC (Constant Amplitude Zero Auto-Correlation) sequence.

The control signal generation unit 107 generates a control signal including the control data output from the upper layer 101 and the reception weight coefficient U ₁ (the reception weight coefficient of the mobile station apparatus connected to the own station) output from the weight coefficient control unit 105. . Here, a control signal generation unit that generates a control signal including a weight coefficient may be referred to as a weight coefficient information generation unit, and a control signal including the weight coefficient generated by the control signal generation unit may be referred to as weight coefficient information. The control signal may be subjected to error correction coding and modulation processing.

FIG. 3 is a conceptual diagram illustrating an example of a format of a control signal output from the control signal generation unit 107. The control signal has an area (cell information area) for storing the reception weight coefficient information of the mobile station apparatus connected to the own station. As shown in FIG. 3, the reception weighting factors U ₁ to the mobile station device 200-1 multiplies the reception signal and reception weight coefficient information, area for storing the information is provided.

  The resource mapping unit 108 maps a modulation symbol, a reference signal, and a control signal to a resource element based on scheduling information notified from the higher layer 101 (hereinafter referred to as resource mapping). This is the minimum unit for arranging a signal consisting of a carrier and one OFDM symbol.

  The IDFT unit 109 performs inverse discrete Fourier transform (IDFT) on the frequency domain signal input from the resource mapping unit 108 to convert it into a time domain signal. The IDFT unit 109 may use another processing method (for example, inverse fast Fourier transform [IFFT, inverse fast Fourier transform]) instead of the IDFT as long as the frequency domain signal can be converted into a time domain signal.

  GI insertion section 110 adds an GI (Guard Interval; also referred to as a guard interval or guard interval) to the time domain signal (referred to as an effective symbol) input from IDFT section 109 to generate an OFDM symbol. The GI is a section added for the purpose of preventing the OFDM symbols of the preceding and succeeding times from interfering with each other. For example, the GI insertion unit 110 prepends a copy of a part of the latter half of the valid symbol as a GI to the valid symbol. Therefore, an effective symbol preceded by GI is an OFDM symbol.

  The transmission unit 111 performs D / A (digital-to-analog) conversion on the OFDM symbol input from the GI insertion unit 110 to generate an analog signal. The transmitting unit 111 generates a band-limited signal by band-limiting the generated analog signal by filtering processing. Transmitting section 111 up-converts the generated band limited signal into a radio frequency band and outputs it to transmitting antenna section 112.

Next, a process of calculating the transmission weight coefficient V _j and the reception weight coefficient U _k in the communication system 1 will be described. FIG. 4 is a flowchart illustrating an example of processing in which the weighting control unit 105 calculates the transmission weight coefficient V _j and the reception weight coefficient U _k .

  In the calculation method of FIG. 4, the complex conjugate transposition matrix of the propagation path matrix from the base station apparatus to the mobile station apparatus becomes a propagation path matrix from the mobile station apparatus to the base station apparatus (reciprocity of propagation paths). Thus, the process of obtaining the weighting coefficient that minimizes the influence of interference is repeated while switching the roles of transmission and reception.

First, when the weighting factor control unit 105 acquires the propagation path information, the weighting factor control unit 105 sets an arbitrary transmission weighting factor V _j (S100).

Next, the weighting factor control unit 105 calculates the total interference Q _{k, i} received by the mobile station apparatus 200-k based on Equation 2 (S101). Here, Q is a covariance matrix of the received interference signal. Further, P is transmission power, and K is the number of mobile station apparatuses that are targets of cooperative control. _H represents complex conjugate transposition.

Next, the weighting coefficient control section 105, the sum _{Q k} of the calculated _{interference, i} and singular value decomposition, the sum _{Q k} of the _{interference,} the receiving weight coefficients _{U k} for suppressing _i, it calculates a _i (S102). In step S102 and step S103, the reception weight coefficient U _k is calculated when the mobile station device 200-k receives the transmission signal of the base station device 100-j.

Next, the roles of transmission and reception of the base station device 100-j and the mobile station device 200-k are switched (S103). That is, the mobile station apparatus 200-k are coefficients _{U k,} the case where the transmission signal a base station apparatus 100-j obtained by multiplying the _i receives, calculates a reception weighting factors _U ^{k ~} of the base station apparatus 100-j . The reception weight coefficient U _k ^˜ corresponds to the transmission weight coefficient V _k of the base station apparatus 100-j.

Regarding the calculation of the reception weight coefficient U _k ^˜ , first, the total interference Q _{j, i} ^˜ received by the base station apparatus 100-j is calculated based on the equation (3) (S104). Here, H _jk ^˜ = H _kj ^H , V _k ^˜ = U _k , P ^˜ is transmission power.

Then, the total sum _{Q j} of the _{interference,} and singular value decomposition of the ^{i ~,} the sum of the interference _{Q j,} receives the weight coefficient _{U k} for suppressing ^{i _~,} calculates the ^{i ~} (S105). Again, the roles of transmission and reception of the base station device 100-j and the mobile station device 200-k are switched (S106). In other _words, substituting _{V k, i = U k,} i ~ a.

  The counter for counting the number of processes is incremented by 1 (S107), and the processes in steps S101 to S106 are repeated until the predetermined number I is reached (N in S108). If the predetermined number of times I has been reached (S108, Y), the process is terminated.

As described above, the reception weight coefficients (U _k , U _k ^˜ ) that repeatedly reduce the interference power are updated repeatedly while switching the roles of transmission and reception of the base station device 100-j and the mobile station device 200-k. As a result, a reception weighting coefficient that allows the base station apparatus 100-j and the mobile station apparatus 200-k to suppress the influence of interference is obtained.

k = j and reception weighting factors _U ^{k ~} a made a transmission weight factor _{V j} of the base station apparatus 100-j, a reception weighting coefficient _{U k} by the receiving weighting factors _{U k} of the mobile station apparatus 200-k, a plurality The base station apparatuses 100-j can suppress the influence of interference in cooperation. This calculation method is an example, and the present invention is not limited to this. Other calculation methods may be used.

  Next, the slave base station devices (base station device 100-2 and base station device 100-3) in the first embodiment will be described. FIG. 5 is a schematic diagram illustrating a configuration of slave base station apparatuses (base station apparatus 100-2 and base station apparatus 100-3) according to the first embodiment. Hereinafter, although it demonstrates as a structure of base station apparatus 100-2, base station apparatus 100-3 also has the same structure.

    The base station apparatus 100-2 includes an upper layer 151, an encoding unit 102, a modulation unit 103, a precoding unit 154, a reference signal generation unit 106, a control signal generation unit 157, a resource mapping unit 108, an IDFT unit 109, and a GI insertion unit. 110, a transmission unit 111, a transmission antenna unit 112, a reception antenna unit 121, a reception unit 122, and a control signal detection unit 123. In addition, when part or all of the base station apparatus 100-2 is formed into a chip to form an integrated circuit, a chip control circuit (not shown) that controls each functional block is provided.

  Compared with base station apparatus 100-1, operations in higher layer 151, precoding section 154, and control signal generation section 157 in base station apparatus 100-2 are different. Hereinafter, mainly different parts will be described.

Upper layer 151 includes propagation path information (propagation path information H ₂₁ between base station apparatus 100-1 and mobile station apparatus 200-2, base station apparatus 100-2, included in the control signal input from control signal detection section 123. And propagation path information H ₂₂ between mobile station apparatus 200-2 and propagation path information H ₂₃ between base station apparatus 100-3 and mobile station apparatus 200-2).

Further, the upper layer 151 notifies the master base station apparatus that calculates the reception weighting coefficient via the backhaul line 10-1 of the propagation path information. Further, the upper layer 151 transmits the transmission weight coefficient V ₂ by which the transmission signal of the own station is multiplied through the backhaul line 10-1 and the reception weight coefficient U ₂ of the mobile station apparatus 200-2 connected to the own station. Is acquired from the master base station apparatus.
The upper layer 151 inputs the transmission weight coefficient V ₂ to the precoding unit 154. Further, the upper layer 151 inputs the reception weight coefficient U ₂ to the control signal generation unit 157.

Precoding section 154 multiplies the transmission weight factor V ₂ to a modulation symbol modulation unit 103 is output.

The control signal generation unit 157 generates a control signal including the control data output from the higher layer 151 and the reception weight coefficient U ₂ (the reception weight coefficient of the mobile station device 200-2 connected to the own station). Similarly, the format shown in FIG. 3 is applied to the format of the control signal. That has an area for storing the received weighting factor information U ₂ of the mobile station device 200-2 are connected to the local station.

  Next, the mobile station device 200-k in the first embodiment will be described. FIG. 6 is a schematic diagram illustrating a configuration of the mobile station apparatus 200-k according to the first embodiment.

  The mobile station apparatus 200-k includes a plurality of reception antenna units 201-e, a plurality of reception units 202-e, a propagation path estimation unit 203, a plurality of GI removal units 204-e, a plurality of DFT units 205-e, and interference suppression. Unit 206, propagation path compensation unit 207, demodulation unit 208, decoding unit 209, control signal detection unit 210 and higher layer 211, control signal generation unit 221, transmission unit 222, and transmission antenna unit 223. In addition, although the example in case mobile station apparatus 200-k has two (e = 2) receiving antennas is shown in FIG. 6, it is not limited to this, and any number of antennas may be provided. Moreover, although it is one transmission antenna, not only this but a several transmission antenna may be provided, and it is good also as a structure which shares a transmission antenna and a reception antenna. In addition, when a part or all of the mobile station device 200-k is formed into a chip to form an integrated circuit, a chip control circuit (not shown) that controls each functional block is provided.

  The mobile station device 200-k receives the transmission signal of the base station device 100-j via the reception antenna unit 201-e. Here, when the mobile station device 200-m (a set of mεk) is connected to the base station device 100-m, transmission signals other than the base station device 100-m cause inter-cell interference.

  The receiving unit 202-e down-converts the radio frequency signal input from the receiving antenna unit 201-e into a frequency band in which digital signal processing is possible, and further performs filtering processing on the down-converted signal to remove unnecessary components (spurious; Remove Spurous). The receiving unit 202-e converts the filtered signal from an analog signal to a digital signal (A / D; Analog-to-Digital), and the converted digital signal is a propagation path estimation unit 203 and a GI removal unit. 204-e and the control signal detection unit 210.

  The GI removal unit 204-e removes the guard interval GI from the signal output from the reception unit 202-e in order to avoid distortion due to the delayed wave, and outputs the removed signal to the DFT unit 205-e.

  The DFT unit 205-e performs Discrete Fourier Transform (DFT: Discrete Fourier Transform) that converts the signal from which the guard interval GI input from the GI removal unit 204-e is removed from a time domain signal to a frequency domain signal, and performs interference. Output to the suppression unit 206. Note that the DFT unit 205-e is not limited to the DFT as long as it can convert the signal from the time domain to the frequency domain, and may perform other methods, for example, Fast Fourier Transform (FFT).

  The propagation path estimation unit 203 performs propagation path estimation using the reference signal included in the signal output from the reception unit 202-e. Then, the propagation path estimation unit 203 notifies the propagation path estimation value to the propagation path compensation unit 207, the control signal generation unit 221, and the upper layer 211. The propagation path estimated value is, for example, a transfer function, an impulse response, or the like.

  The control signal detection unit 210 detects a control signal included in the signal output from the reception unit 202-e. Then, when the control signal detection unit 210 extracts the reception weight coefficient information (see FIG. 3) included in the control signal, the control signal detection unit 210 inputs the information to the interference suppression unit 206. In addition, when the control signal detection unit 210 extracts the information about the MCS and the number of layers applied to the information data included in the control signal, the control signal detection unit 210 notifies the demodulation unit 208 and the decoding unit 209 of the information.

  The interference suppression unit 206 multiplies the frequency domain signal input from the DFT unit 205-e by the reception weight coefficient input from the control signal detection unit 210.

  The propagation path compensation unit 207, based on the propagation path estimation value input from the propagation path estimation unit 203, performs ZF (Zero Forcing) equalization, MMSE (Minimum Mean Square Error) equalization, etc. Using a method, a weighting factor for correcting propagation path distortion due to fading is calculated. The propagation path compensation unit 207 performs propagation path compensation by multiplying the signal input from the interference suppression unit 206 by this weight coefficient.

  Demodulation section 208 performs demodulation processing on the signal (data modulation symbol) after propagation path compensation input from propagation path compensation section 207. The demodulation process may be either a hard decision (calculation of a coded bit sequence) or a soft decision (calculation of a coded bit LLR).

  The decoding unit 209 performs error correction decoding processing on the encoded bit sequence (or encoded bit LLR) after demodulation output from the demodulation unit 208, calculates information data transmitted to itself, 211 is output. This error correction decoding processing method is a method corresponding to error correction coding such as turbo coding and convolution coding performed by the connected base station apparatus 100-m. Either a hard decision or a soft decision can be applied to the error correction decoding process.

  When base station apparatus 100-j transmits interleaved data modulation symbols, decoding section 209 performs the deinterleaving corresponding to the interleaving on the input coded bit sequence before performing the error correction decoding process. Process. Then, the decoding unit 209 performs error correction decoding processing on the signal that has been subjected to deinterleaving processing.

The control signal generation unit 221 generates a control signal including propagation path information between the own station and the base station device 100-j. For example, in the communication system 1 in FIG. 1, the control signal of the mobile station device 200-1 includes the propagation path H ₁₁ between the mobile station device 200-1 and the base station device 100-1 that cooperates with the mobile station device 200-1. Includes propagation path information of propagation path H ₁₂ between base station apparatus 100-2 cooperating with 200-1 and propagation path H ₁₃ between base station apparatus 100-3 cooperating with mobile station apparatus 200-1. It is.

  Further, the control signal generation unit 221 generates a control signal for transmitting feedback information (including CQI, RI, and PMI) to the base station apparatus. The feedback information is determined by the upper layer 211 based on the channel estimation value calculated by the channel estimation unit 203.

  Further, the control signal generation unit 221 generates control signals by performing error correction coding and modulation mapping on control data indicating feedback information. The signal including the control signal output from the control signal generation unit 221 is up-converted by the transmission unit 222 before the frequency band that can be transmitted in the downlink, and is connected via the transmission antenna unit 223 to the base station apparatus 100- sent to j.

  Next, the process in the interference suppression unit 206 of the mobile station device 200-k will be specifically described. The following is an example when the mobile station has two antennas (e = 2).

ここで、Ｒ_ｋ、ｅは移動局装置ｋのＤＦＴ部２０５−ｅから入力される信号、Ｈ_ｋｊ、ｅは基地局装置１００−ｊ（ｊ＝１〜３）の送信信号を移動局装置２００−ｋが受信アンテナ部２０１−ｅを介して受信した場合の伝搬路（伝達関数）、Ｖ_ｊは基地局装置１００−ｊの送信信号に乗算されている送信重み係数（各基地局装置のプレコーディング部１０４で乗算）、Ｓ_ｊは基地局装置１００−ｊのデータ変調シンボルである。また、＋（式４及び式５では丸プラスで表す）は要素毎の加算である。 In the mobile station apparatus 200-k, a signal input from DFT section 205-1 and the DFT unit 205-2 to the interference suppression unit 206 as a vector _{R k,} can be expressed as follows using Equation 4.

Here, R _{k and e} are signals input from the DFT unit 205- _e of the mobile station apparatus k, H _{kj and e} are transmission signals of the base station apparatus 100-j (j = 1 to 3), and the mobile station apparatus 200. channel when -k is received through the reception antenna unit 201-e (transfer function), up to V _j is the transmission weight factor that is multiplied to the transmission signal of the base station apparatus 100-j (each base station apparatus S _j is a data modulation symbol of base station apparatus 100-j. Further, + (represented by a circle plus in Equations 4 and 5) is addition for each element.

Further, when the interference suppression unit 206 multiplies the above R _k by the reception weight coefficient U _k as Y _k , it can be expressed as Equation 5. Here, U _{k and e} are reception weighting factors by which a signal input from the DFT unit 205- _e of the mobile station apparatus 200-k is multiplied.

Next, the notification procedure of the transmission weight coefficient V _j and the reception weight coefficient U _k in the communication system 1 will be described.

In FIG. 7, the master base station apparatus (base station apparatus 100-1) of the communication system 1 calculates the transmission weight coefficient V _j and the reception weight coefficient U _k , and the slave base station apparatuses (base station apparatuses 100-2 and 100-). It is a sequence diagram which shows the operation example notified to 3) and the mobile station apparatus 200-k.

  First, the master base station apparatus makes a channel information notification request to the slave base station apparatus that cooperatively transmits data (S201).

  Each slave base station apparatus that has received the notification request in step S201 makes a propagation path information notification request to each of the connected mobile station apparatuses 200-2 and 200-3 (S202).

  On the other hand, the mobile station apparatus 200-1 connected to the master base station apparatus receives a propagation path information notification request directly from the master base station apparatus.

    Upon receiving the propagation path information notification request (S202), all mobile station apparatuses 200-k estimate the propagation path with each of the cooperating base station apparatuses (S203).

In the communication system 1, the mobile station device 200-k estimates the propagation path H _k1 , the propagation paths H _k2 and H _k3 . Propagation path estimation is performed using the reference signal which each base station apparatus 200-j transmits, for example.

  Next, the mobile station device 200-k notifies the base station device 100-j, which is the request source of the propagation path information notification, of the propagation path estimation result (propagation path information) (S204).

  Next, the slave base station apparatuses (base station apparatuses 100-2 and 100-3) that have received the notification of the propagation path information (S204) notify the master base station apparatus (base station apparatus 100-1) of the propagation path information. (S205).

  Specifically, in the communication system 1, the base station device 100-1 requests the base station device 100-2 to notify the channel information of the connected mobile station device 200-2. Then, base station apparatus 100-2 requests propagation path information notification to mobile station apparatus 200-2. Similarly, the base station apparatus 100-3 requests for propagation path information notification.

  On the other hand, the mobile station apparatus 200-1 connected to the master base station apparatus notifies the master base station apparatus of the propagation path information directly.

  As a result, the master base station apparatus obtains all propagation path information between all base station apparatuses and mobile station apparatuses that perform data transmission in a coordinated manner.

Next, the master base station apparatus calculates a transmission weight coefficient V _j and a reception weight coefficient U _k using the propagation path information obtained in step S205 (S206).

Then, the master base station apparatus notifies the calculated transmission weight coefficient V _j to the slave base station apparatus 100-j using the backhaul line (S207).

Also, the master base station apparatus notifies the reception weight coefficient U _k of each mobile station apparatus via the base station apparatus to which each mobile station apparatus is connected (S207, S208). For example, the mobile station device 200-2 that are connected to the slave base station device 100-2 via the slave base station device 100-2, to obtain the receive weighting factors _{U 2} from the master base station device 100-1 become.

The master base station apparatus, the reception weighting factors U ₁ of the mobile station device 200-1 that are connected to the local station to directly notify the mobile station apparatus (S209).

Then, the master base station device and the slave base station device multiply the information data to be transmitted to the mobile station devices connected to each by the transmission weight coefficient V _j (S210, S211), and transmit (S212, S213).

As described above, in the first embodiment, in the communication system 1 in which the cells of the plurality of base station devices 100-j are arranged so that all or some of them overlap, the master base station device Each base station is configured such that the direction of the equivalent propagation path of the interference signal received by mobile station apparatus 200-k connected to apparatus 100-j is orthogonal to the reception weight coefficient that mobile station apparatus 200-k multiplies the received signal. It calculates a reception weighting factor _{U k} of the transmission weight factor _{V j} and the mobile station apparatus 200-k of the station apparatus 100-j.

Then, the base station apparatus 100-j notifies the reception weight coefficient U _k to the mobile station apparatus 200-k connected to the own station, and the mobile station apparatus 200-k receives the reception weight coefficient for the received signal (including the interference signal). Multiply U _k to perform reception processing.

  As a result, in a communication system in which cells in a plurality of base station apparatuses having different cell ranges are arranged so as to overlap all or partly, the plurality of base station apparatuses communicate using the same frequency. Inter-cell interference can be effectively suppressed and good reception characteristics can be obtained.

  Note that the weighting factor control unit 105 of the base station apparatus 100-1 may be included in the upper layer 101. Further, the weight coefficient control unit 105 may be included in a base station management unit that is located outside a plurality of cooperating base station devices 100-j and supervises these base station devices 100-j.

<Second Embodiment>
In the second embodiment, in the communication system 1 in which the plurality of base station apparatuses 100-j described in the first embodiment cooperate to suppress inter-cell interference, a code book is prepared, and the base station apparatus 100- A method in which j notifies the mobile station apparatus 200-k of the reception weight coefficient U _k will be described. The code book is a list of transmission weighting factors V _j and reception weighting factors U _k determined in advance in the communication system 1.

The base station apparatus 100-j in the communication system 1 of the second embodiment shares the codebook of the transmission weight coefficient V _j of the base station apparatus and the reception weight coefficient U _k of the mobile station apparatus, and the mobile station apparatus 200-k Are configured to share at least the code book of the reception weight coefficient U _k of the mobile station apparatus 200-k.

An example of the code book is shown in FIG. In FIG. 8, transmission weight coefficients V _{j, n} are nth transmission weight coefficient candidates in the j-th base station apparatus (j and n are arbitrary positive integers). Also, the reception weight coefficient U _{k, n} is the nth reception weight coefficient candidate in the kth mobile station apparatus (k and n are arbitrary positive integers).

In the code book of FIG. 8, code book indexes # 0 to 3 are transmission weight coefficients V _j and reception weights for suppressing inter-cell interference in cooperation between two base station apparatuses and two mobile station apparatuses. This is a candidate for the coefficient U _k . Codebook indexes # 4 to # 7 are candidates for transmission weight coefficient V _j and reception weight coefficient U _k that suppress inter-cell interference in cooperation between three base station apparatuses and three mobile station apparatuses. . Codebook indexes # 8 to 11 are candidates for transmission weight coefficient V _j and reception weight coefficient U _k that suppress inter-cell interference in cooperation between the four base station apparatuses and the four mobile station apparatuses.

Next, selection of the transmission weight coefficient V _j and the reception weight coefficient U _k will be described using a code book.

    For example, the master base station device 100-1 holds the code book in the weighting coefficient control unit 105. First, the weight coefficient control unit 105 selects codebook candidates from the number of cooperating base station apparatuses and the number of mobile station apparatuses input from the upper layer 101.

  In the case of the communication system 1 shown in FIG. 1, since the three base station devices 100-j and the three mobile station devices 200-k cooperate, codebook indexes # 4 to # 7 are selected as candidates.

Next, the weighting factor control unit 105 uses the propagation path information H _kj input from the upper layer 101 and the selected codebook index candidate, so that the receiving weighting factor U _k that minimizes the influence of interference is _obtained. The process which asks for is performed.

For example, the transmission weight coefficient V _j and the reception weight coefficient U _k of the propagation path information H _kj and the candidate codebook index are substituted into Equations 2 and 3, and the interference sums Q _{k and i} and the sum Q _{j, i} Select the codebook that minimizes ^~ .

Next, a method for notifying the transmission weight coefficient V _j and the reception weight coefficient U _k will be described using a code book.

  The sequence shown in FIG. 7 is applied to the sequence of operations for notifying the slave base station device and the mobile station device of the codebook index selected by the master base station device.

  In this case, “Notification of transmission weight coefficient and reception weight coefficient” (S207) and “Notification of reception weight coefficient” (S208 and S209) in FIG. 7 are replaced with “Notification of codebook index”.

  Then, the master base station apparatus notifies the selected codebook index to the slave base station apparatus using the backhaul lines 10-1 and 10-2.

  Next, the format of the control signal output by the control signal generation unit 107 will be described. FIG. 9 is a conceptual diagram illustrating an example of a format of a control signal output from the control signal generation unit 107.

The control signal has a codebook index area for notifying information on the reception weight coefficient U _k of the mobile station apparatus connected to the own station. 9, as an example, the reception weighting factors U ₁ to the mobile station device 200-1 multiplies the reception signal and reception weight coefficient information indicates the case where is provided a 4-bit area for storing the information.

Also, the control signal generation unit 157 of the slave base station apparatus notifies the reception weight coefficient U _k to the mobile station apparatus 200-k by the format of the control signal shown in FIG.

As described above, by sharing the code book between the base station apparatus 100-j and the mobile station apparatus 200-k, it is possible to reduce the number of repetitions when calculating the transmission weight coefficient V _j and the reception weight coefficient U _k. Therefore, it is possible to reduce the processing load on the base station device 100-j and the mobile station device 200-k. In addition, since the reception weight coefficient U _k can be notified to the mobile station apparatus 200-k by notifying the codebook index, the overhead (storage area for notifying the weight coefficient of the control signal) can be reduced.

<Third Embodiment>
In the third embodiment, in the communication system 1 in which a plurality of base station apparatuses 100-j described in the first embodiment cooperate to suppress inter-cell interference, the base station apparatus 100 is used by using a plurality of reference signals. A mode in which −j uses a method of notifying mobile station apparatus 200-k of reception weight coefficient U _k will be described.

  As illustrated in FIG. 10, the communication system 1 a according to the third embodiment includes a base station device 300-1 that is a master base station device, base station devices 300-2 and 300-3 that are slave base station devices, and a plurality of Mobile station devices 400-1 to 400-3 are provided. In the communication system 1a according to the third embodiment, the base station device 100-1 of FIG. 1 is replaced with the base station device 300-1, and the base station devices 100-2 and 100-3 of FIG. 2 and 300-3, the mobile station device 200-1 to the mobile station device 200-3 can be replaced with the mobile station device 400-1 to the mobile station device 400-3.

  FIG. 11 is a schematic diagram illustrating a configuration of a base station apparatus 300-1 according to the third embodiment. The base station apparatus 300-1 includes an upper layer 101, an encoding unit 102, a modulation unit 103, a precoding unit 104, a weight coefficient control unit 305, a reference signal generation unit 306, a control signal generation unit 107, a resource mapping unit 108, an IDFT. Unit 109, GI insertion unit 110, transmission unit 111, transmission antenna unit 112, reception antenna unit 121, reception unit 122, and control signal detection unit 123. In addition, when part or all of the base station apparatus 300-1 is formed into a chip to form an integrated circuit, a chip control circuit (not shown) that controls each functional block is provided.

  In the base station apparatus 300-1, the components having the same reference numbers as those in FIG. When compared with the base station apparatus 300-1 of the third embodiment and the base station apparatus 100-1 of the first embodiment, the weight coefficient control unit 305 and the reference signal generation unit 306 are different. Hereinafter, these parts will be mainly described.

The weight coefficient control unit 305 is connected to the transmission weight coefficient V _j to be multiplied by the signal transmitted by the base station apparatus and the slave base station apparatus and the base station apparatus using the propagation path information acquired from the upper layer 101. The mobile station apparatus calculates a reception weight coefficient U _k by which the reception signal is multiplied. As a method for calculating the transmission weight coefficient V _{j and the} reception weight coefficient U _k , the same method as in the first embodiment can be applied.

Also, the weight coefficient control unit 305 notifies the upper layer of the transmission weight coefficient V _j of the slave base station apparatus and the reception weight coefficient U _k of the mobile station apparatus connected to the slave base station apparatus. Further, the weighting factor controller 305, outputs the transmission weight factor V ₁ to be multiplied by the transmission signal of the master base station (own station) in the precoding unit 104. Furthermore, the weight coefficient control unit 305 outputs the reception weight coefficient U ₁ of the mobile station apparatus connected to the master base station apparatus (own station) to the reference signal generation unit 306.

The reference signal generation unit 306 uses the first reference signal used for estimating the propagation characteristics from the transmission antenna of the base station apparatus 300-j to each reception antenna of the mobile station apparatus 300-k, and the reception weight coefficient U ₁ . A second reference signal used for notifying the mobile station apparatus is generated. The second reference signal is generated by multiplying the received weighting factor U ₁ to a known code sequence previously determined by the communication system 1a. Here, a reference signal generation unit that generates a reference signal including a weight coefficient may be referred to as a weight coefficient information generation unit, and a reference signal including the weight coefficient generated by the reference signal generation unit may be referred to as weight coefficient information.

For example, when a known code sequence previously determined in the communication system 1a and _{S RS,} the first reference _signal, becomes _{S RS,} the second reference _signal, the U _{1 S RS.}

  Based on the scheduling information notified from the higher layer 101, the resource mapping unit 108 transmits the modulation symbol, the first reference signal, the second reference signal, and the control signal output from the precoding unit 104 to the resource mapping unit 108. Map resources to resource elements.

  Next, the base station apparatus 300-2 and the base station apparatus 300-3 (slave base station apparatus) according to the third embodiment will be described.

  FIG. 12 is a schematic diagram illustrating configurations of the base station device 300-2 and the base station device 300-3 according to the third embodiment. Hereinafter, the configuration of the base station apparatus 300-2 will be described, but the base station apparatus 300-3 has the same configuration. Further, the number of slave base station devices is not limited to two as long as it includes at least one base station device.

    Base station apparatus 300-2 includes higher layer 152, encoding section 102, modulation section 103, precoding section 154, reference signal generation section 356, control signal generation section 157, resource mapping section 108, IDFT section 109, and GI insertion section. 110, a transmission unit 111, a transmission antenna unit 112, a reception antenna unit 121, a reception unit 122, and a control signal detection unit 123. In addition, when a part or all of the base station apparatus 300-2 is formed into a chip to form an integrated circuit, a chip control circuit (not shown) that controls each functional block is provided.

  In the base station apparatus 300-2, the components having the same reference numbers as those in FIG. When compared with the base station apparatus 300-2 of the third embodiment and the base station apparatus 100-2 of the first embodiment, the upper layer 152 and the reference signal generation unit 356 are different. Hereinafter, these parts will be mainly described.

Upper layer 152 includes propagation path information (propagation path information H ₂₁ between base station apparatus 300-1 and mobile station apparatus 400-2, base station apparatus 300-2, included in the control signal input from control signal detection section 123. And propagation path information H ₂₂ between mobile station apparatus 400-2 and propagation path information H ₂₃ between base station apparatus 300-3 and mobile station apparatus 400-2).

Further, the upper layer 152 notifies the acquired propagation path information to the master base station apparatus that calculates the reception weight coefficient U _k through the backhaul line 10-1 (or the backhaul line 10-2).

The upper layer 152 is connected to the transmission weight coefficient V ₂ (or V ₃ ) for multiplying the transmission signal of the own station and the own station through the backhaul line 10-1 (or the backhaul line 10-2). The reception weight coefficient U ₂ (or U ₃ ) of the mobile station device 400-2 is acquired from the master base station device.

Further, the upper layer 152 inputs the transmission weight coefficient V ₂ (or V ₃ ) to the precoding unit 154. Further, the upper layer 152 inputs the reception weight coefficient U ₂ (or U ₃ ) to the reference signal generation unit 356.

The reference signal generation unit 356 includes a first reference signal _SRS1 used for estimating a propagation characteristic from the transmission antenna of the base station apparatus to the reception antenna of each mobile station apparatus, and a reception weight coefficient U ₂ (or U ₃ ). To the mobile station device 400-2, a second reference signal _SRS2 is generated. Note that the reference signal generation method in the reference signal generation unit 306 of the base station device 300-1 is applied to the reference signal generation method in the reference signal generation unit 356 of the base station devices 300-2 and 300-3.

  Based on the scheduling information notified from the higher layer 152, the resource mapping unit 108 transmits the modulation symbol, the first reference signal, the second reference signal, and the control signal output from the precoding unit 154 to the resource mapping unit 108. Map resources to resource elements. The format in the reference signal generation unit 106 of the base station apparatus 300-1 is applied as the resource mapping format.

  Next, the configuration of the mobile station apparatus 400-k according to the third embodiment will be described.

  FIG. 13 is a schematic diagram illustrating a configuration of a mobile station device 400-k according to the third embodiment. The mobile station device 400-k includes a reception antenna unit 201-e, a reception unit 202-e, a propagation path estimation unit 203, a GI removal unit 204-e, a DFT unit 205-e, an interference suppression unit 206, and a propagation path compensation unit 207. A demodulating unit 208, a decoding unit 209, a control signal detecting unit 410, an upper layer 211, a control signal generating unit 221, a transmitting unit 222, and a transmitting antenna unit 223. FIG. 13 is an example of two antennas (e = 1, 2). When a part or all of the mobile station device 400-k is formed into a chip to form an integrated circuit, a chip control circuit (not shown) that controls each functional block is provided.

  In the mobile station device 400-k, the components with the same reference numbers as those in FIG. When compared with the mobile station apparatus 400-k of the third embodiment and the mobile station apparatus 200-k of the first embodiment, the control signal detection unit 410 is different. In the following, the description will be made centering on the portion.

The propagation path estimation unit 203 performs propagation path estimation using the first reference signal _SRS1 included in the signal output from the reception unit 202-1. Then, the propagation path estimation value (for example, transfer function) is notified to the control signal detection section 410, the propagation path compensation section 207, the control signal generation section 221 and the upper layer 211.

The propagation path estimation unit 203 outputs the first reference signal HS _RS1 (H _k is a propagation path between the base station apparatus 300-j (where j = k) and the mobile station apparatus 400-k) output from the reception unit 202-e. _Is divided by the known signal _SRS1 to calculate the propagation path estimated value H ^.

Further, the channel estimation value of the subcarrier where the known signal S _RS1 is not arranged is linear interpolation, FFT interpolation, etc. using the channel estimation value H _k ^ of the subcarrier where the first reference signal HS _RS1 is arranged. It can be calculated by the interpolation technique.

  The control signal detection unit 410 detects a control signal included in the signal output from the reception unit 202-2. When the information on the MCS and the number of layers applied to the information data included in the control signal is extracted, the information is notified to the demodulation unit 208 and the decoding unit 209.

Further, the control signal detection unit 410 calculates reception weight coefficient information U _k ^ using the second reference signal S _RS2 (= U _k S _RS1 ) included in the signal output from the reception unit 202-2. Then, the reception weight coefficient information U _k ^ is input to the interference suppression unit 206. The calculated reception weight coefficient information U _k ^ can be expressed by the following Equation 6. Here, H _k ^ is a propagation path estimated value.

The interference suppression unit 206 performs processing represented by Expression 5 using the calculated reception weight coefficient information U _k ^.

  Next, resource mapping in the resource mapping unit 108 of the base station apparatus 300-1 according to the third embodiment will be described. FIG. 14 is an example of resource mapping in the resource mapping unit 108 of the base station apparatus 300-1 according to the third embodiment.

  The resource mapping in the resource mapping unit 108 shown in FIG. 14 is an example when the base station apparatus 300-1 transmits using one transmission antenna unit. In FIG. 14, the horizontal direction indicates time T, and the vertical direction indicates frequency F. In FIG. 14, an outline part RE1 is a resource element that maps a control signal and information data.

  The hatched portion RE2 and the painted portion RE3 are resource elements for mapping the reference signal. Resource elements to which the reference signal can be mapped are included in the entire system band. That is, it is a resource element that maps a cell-specific reference signal.

  Then, among the resource elements to which the reference signal is mapped, the first reference signal is arranged in the painting unit RE3. Also, the second reference signal is arranged in the shaded area RE2 among the resource elements for mapping the reference signal.

Thus, by multiplying the received weighting factor U _k to the portion of the cell-specific reference signal, and notifies the reception weighting coefficient U _k to the mobile station apparatus. The information data and the control signal may be subjected to error correction coding and modulation processing (the same applies to FIGS. 15 to 17).

  FIG. 15 is another example of resource mapping in the resource mapping unit 108 of the base station apparatus 300-1 according to the third embodiment.

  In FIG. 15, the horizontal direction indicates time T, and the vertical direction indicates frequency F. In FIG. 15, a white portion RE1 is a resource element that maps a control signal and information data. The range of the thick line is the range MA to which the modulation symbol of the mobile station apparatus that notifies the reception weight coefficient is assigned.

The hatched portion RE2 and the painted portion RE3 are resource elements for mapping the reference signal. The resource element to which the reference signal can be mapped has a range in which the modulation symbol of the mobile station apparatus that notifies the reception weight coefficient U _k is allocated. That is, it is a resource element that maps a user-specific reference signal.

  Then, among the resource elements for mapping the reference signal, the first reference signal is arranged in the painting unit RE3. Also, the second reference signal is arranged in the shaded area RE2 among the resource elements for mapping the reference signal.

Thus, by multiplying a part of the user-specific reference signal by the reception weight coefficient U _k , the reception weight coefficient is notified to the mobile station apparatus.

  FIG. 16 is another example of resource mapping in the resource mapping unit 108 of the base station apparatus 300-1 according to the third embodiment.

  In FIG. 16, the horizontal direction indicates time T, and the vertical direction indicates frequency F. In FIG. 16, a white portion RE1 is a resource element that maps a control signal and information data. The thick line area is an area MA to which the modulation symbol of the mobile station apparatus that notifies the reception weight coefficient is assigned.

  Also, the hatched part RE2 and the painted part RE3 are resource elements for mapping the reference signal. The resource element that can map the reference signal indicated by the filling unit RE3 is a resource element that maps the cell-specific reference signal. The resource element that can map the reference signal indicated by the hatched portion RE2 is a resource element that maps the user-specific reference signal.

  Then, among the resource elements for mapping the reference signal, the first reference signal is arranged in the painting unit RE3. Also, the second reference signal is arranged in the shaded area RE2 among the resource elements for mapping the reference signal.

  In this way, by multiplying either the user-specific reference signal or the cell-specific reference signal by the reception weight coefficient Uk, the mobile station apparatus is notified of the reception weight coefficient.

  FIG. 17 is another example of resource mapping in the resource mapping unit 108 of the base station apparatus 300-1 according to the third embodiment.

  In FIG. 17, the horizontal direction indicates time T, and the vertical direction indicates frequency F. In FIG. 17, a white portion RE1 is a resource element that maps a control signal and information data. The bold line area is a resource block RB. A resource block is a resource unit in which a plurality of resource elements are collected, and is a minimum resource unit to which a modulation symbol is allocated for each mobile station apparatus. In FIG. 17, the resource block RB can be a resource composed of 12 subcarriers and 7 OFDM symbols.

  The hatched portion RE2 and the painted portion RE3 are resource elements for mapping the reference signal. The resource element that can map the reference signal indicated by the filling unit RE3 is a resource element that maps the cell-specific reference signal. The resource element that can map the reference signal indicated by the hatched portion RE2 is a resource element that maps the user-specific reference signal.

  Then, among the resource elements for mapping the reference signal, the first reference signal is arranged in the painting unit RE3. Also, the second reference signal is arranged in the shaded area RE2 among the resource elements for mapping the reference signal.

  In this way, the reference signal is either a reference signal unique to each mobile station device or a reference signal unique to a cell, and is included in a part of resource blocks in a region to which modulation symbols of the mobile station device are mapped. By multiplying the reception weight coefficient, the mobile station apparatus is notified of the reception weight coefficient.

  As described above, in the communication system according to the third embodiment, the cells of the plurality of base station devices are arranged so as to overlap all or part of the cells, and are connected to the plurality of base station devices and the base station device. Each mobile station apparatus cooperates to suppress inter-cell interference. Since the base station apparatus notifies the mobile station apparatus of a reception weight coefficient for suppressing inter-cell interference using the reference signal, the base station apparatus can prevent an increase in the control signal, and a plurality of base station apparatuses and It is possible to realize a communication system that can reduce the load of control signal processing in each mobile station apparatus. In addition, the base station apparatus can notify the weighting factor using a mobile station apparatus or a cell-specific reference signal, and can construct a communication system capable of efficiently receiving and transmitting data corresponding to the communication environment.

  In this embodiment, the method of multiplying the reference signal by the reception weight coefficient and notifying the mobile station apparatus of the reception weight coefficient has been described. However, the present invention is not limited to this, and the signal multiplied by the reception weight coefficient is a known signal. If it is. For example, a configuration may be adopted in which a control signal that is a known signal is multiplied by a reception weight coefficient, and the reception weight coefficient is notified to the mobile station apparatus.

  The program that operates in the base station apparatus and the mobile station apparatus according to the present invention is a program that controls the CPU and the like (a program that causes a computer to function) so as to realize the functions of the above-described embodiments related to the present invention. 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. Moreover, you may implement | achieve part or all of the mobile station apparatus and base station apparatus in embodiment mentioned above as LSI which is typically an integrated circuit. Each functional block of the receiving apparatus may be individually formed as a chip, or a part or all of them may be integrated into a chip. When each functional block is integrated, an integrated circuit controller for controlling them is added.

  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 the design and the like within the scope not departing from the gist of the present invention are also claimed. Included in the range.

DESCRIPTION OF SYMBOLS 1 Communication system 100-1 (Master) base station apparatus 100-2, 100-3 (Slave) base station apparatus 101, 211 Upper layer 102 Encoding part 103 Modulation part 104 Precoding part 105 Weight coefficient control part 106 Reference signal generation part 107, 221 Control signal generation unit 108 Resource mapping unit 109 IDFT unit 110 GI insertion unit 111, 223 Transmission unit 112, 221 Transmission antenna unit 121, 201-1, 201-2 Reception antenna unit 122, 202-1, 202-2 Receiving unit 123 Control signal detecting unit 200-1, 200-2, 200-3 Mobile station apparatus 203 Propagation path estimating unit 204-1, 204-2 GI removing unit 205-1, 205-2 DFT unit 206 Interference suppressing unit 207 Propagation path compensator 208 Demodulator 209 Decoder 210 Control signal Detection unit

Claims (13)

A plurality of base station devices, and a mobile station device connected to at least one of the plurality of base station devices, wherein the plurality of base station devices have a total range or a part of a connectable range of each base station device. A communication system arranged to overlap each other,
The base station apparatus notifies the mobile station apparatus of information related to a weighting coefficient that indicates a reception weighting coefficient to be multiplied with a reception signal received by the mobile station apparatus. The plurality of base station devices include a master base station device and a slave base station device,
The main base station apparatus is
A transmission weight coefficient to be multiplied with transmission data transmitted by the plurality of base station apparatuses using propagation path information of the entire system, and reception received by the mobile station apparatus to which each of the plurality of base station apparatuses is connected. A weight coefficient control unit for calculating a reception weight coefficient to be multiplied with the signal,
The plurality of base station devices are:
A precoding unit that multiplies the transmission data by the transmission weighting factor, a weighting factor information generation unit that generates weighting factor information indicating the reception weighting factor, and information data obtained by multiplying the transmission data by the transmission weighting factor, A transmitter that transmits the weighting factor information to the mobile station apparatus to which each of the plurality of base station apparatuses is connected;
The mobile station device
The control signal detection unit that detects a reception weight coefficient from the weight coefficient information, and an interference suppression unit that multiplies the reception signal by the reception weight coefficient to acquire the information data. The communication system described.   3. The communication according to claim 2, wherein the weighting factor information is a control signal including a reception weighting factor for multiplying a reception signal received by each mobile station device connected by the base station device. system.   The communication according to claim 2, wherein the weighting factor information is a control signal including a codebook index corresponding to a transmission weighting factor of the plurality of base station devices and the reception weighting factor of the mobile station device. system. The communication system according to claim 2, wherein the weighting factor information is a reference signal multiplied by the reception weighting factor.   The communication system according to claim 5, wherein the reference signal is a part of a reference signal unique to the mobile station apparatus.   The communication system according to claim 5, wherein the reference signal is a part of a reference signal specific to a cell of the base station apparatus.   The communication system according to claim 5, wherein the reference signal is a reference signal specific to the mobile station apparatus or a reference signal specific to a cell of the base station apparatus. The main base station apparatus is
The communication system according to claim 2, further comprising an upper layer that notifies the slave base station apparatus of information related to the transmission weight coefficient and information related to the reception weight coefficient. The slave base station device
The communication system according to claim 9, further comprising a weighting factor information generation unit that generates weighting factor information including information on the reception weighting factor notified from the higher layer. A plurality of base station devices, and a mobile station device connected to at least one of the plurality of base station devices, wherein the plurality of base station devices have a total range or a part of a connectable range of each base station device. A communication method in a communication system arranged to overlap each other,
The base station apparatus performs a step of notifying the mobile station apparatus of reception weight coefficient information indicating a reception weight coefficient to be multiplied by a reception signal received by the mobile station apparatus. A plurality of base station devices including a main base station device and a slave base station device; and a mobile station device connected to at least one of the plurality of base station devices, wherein the plurality of base station devices A base station apparatus in a communication system arranged so that all or part of the connectable range of station apparatuses overlap each other,
The main base station apparatus is
A transmission weight coefficient to be multiplied with transmission data transmitted by the plurality of base station apparatuses using propagation path information of the entire system, and reception received by the mobile station apparatus to which each of the plurality of base station apparatuses is connected. A weight coefficient control unit for calculating a reception weight coefficient to be multiplied with the signal,
The plurality of base station devices are:
Precoding unit for multiplying the transmission weight factor by the transmission weight factor, weight factor information generating unit for generating reception weight factor information for instructing the reception weight factor, and information data by multiplying the transmission data by the transmission weight factor And a reception weight coefficient information to the mobile station apparatus to which each of the plurality of base station apparatuses is connected. A plurality of base station devices including a main base station device and a slave base station device; and a mobile station device connected to at least one of the plurality of base station devices, wherein the plurality of base station devices A mobile station apparatus in a communication system arranged so that all or part of the connectable range of the station apparatus overlaps each other,
The mobile station device
A receiving unit that receives a reception signal and reception weight coefficient information multiplied by a transmission weight coefficient calculated by the main base station apparatus using propagation path information of the entire system;
A mobile station apparatus comprising: a control signal detector that detects a reception weight coefficient from the reception weight coefficient information; and an interference suppression unit that multiplies the reception weight coefficient by the reception signal to acquire the information data. .

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