JP2013106249A - 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-k is arranged such that all or part of the cell will overlap with another cell, each base station device 100-k calculates a transmission weighting coefficient Vof each mobile station device 200-j and a reception weighting coefficient Uof the base station device 100-k such that the direction of an equivalent propagation path of an interference signal received by each base station device 100-k will be orthogonal to the reception weighting coefficient Uby which the base station device 100-k multiplies the reception signal. Then, the base station device 100-k notifies the mobile station device 200-j connected to the own station of the transmission weighting coefficient V, and the mobile station device 200-j performs transmission processing by multiplying the transmission signal by the transmission weighting coefficient V.

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.

  Further, in the cellular configuration, the same frequency is repeatedly used in the cell of the base station apparatus in order to improve the frequency utilization efficiency. However, in the cellular configuration, if inter-cell interference occurs due to repetition of the same frequency, improvement in frequency utilization efficiency is limited.

  Inter-cell interference coordination (ICIC) using an indicator OI (Overload Indicator), an indicator HII (High Interference Indicator), or the like as a method for suppressing and reducing inter-cell interference in an uplink having a cellular configuration. It is used (Non-patent Document 1). The indicator OI is a control signal for notifying another base station apparatus when a certain base station apparatus has a high interference level from a mobile station apparatus connected to the other base station apparatus. The indicator HII is a control signal that is located at the cell edge of the base station device and receives a signal from a mobile station device that transmits with high transmission power, and notifies other base station devices to that effect. .

  FIG. 18 shows an outline of a conventional wireless communication system 1000 in the uplink to which the inter-cell interference adjustment ICIC is applied. Base station apparatus 1000-1 and base station apparatus 1000-2 each include cell 1000-2a with cell 1000-1a, and cell 1000-1a of base station apparatus 1000-1 and cell of base station apparatus 1000-2. Each base station apparatus is arranged with 1-cell frequency repetition so that 1000-2a partially overlaps. A plurality of mobile station apparatuses exist in each cell, and each mobile station apparatus is controlled so as to be wirelessly connected to a base station apparatus that can receive a signal with an optimum received electric field strength.

  Base station apparatus 1000-1 is connected (r11) with mobile station apparatus 2000-1. In addition, the base station apparatus 1000-1 receives interference (r21) from the mobile station apparatus 2000-2 connected to the base station apparatus 1000-2 (r22).

  The base station apparatus 1000-1 receiving the interference (r21) notifies the indicator OI to the base station apparatus 1000-2 via the backhaul line 10 (for example, an optical fiber, an X2 interface, etc.). The base station apparatus 1000-2 that has received the indicator OI suppresses and reduces inter-cell interference by causing the mobile station apparatus 2000-2 to stop transmission.

  Also, the base station apparatus 1000-2 notifies the base station apparatus 1000-1 of the indicator HII via the backhaul line 10 before the mobile station apparatus 2000-2 transmits a signal (r22). Receiving the indicator HII, the base station apparatus 1000-1 suppresses and reduces interference by performing scheduling so that the signal (r11) from the mobile station apparatus 2000-1 does not receive interference.

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 macrocells configured by the main base station apparatus (macro base station) and a small power base station (picocell base station, femtocell base station, etc.) whose maximum transmission power is smaller than that of the macro base station It is proposed that a plurality of base station apparatuses be arranged so as to overlap the cell range of () (heterogeneous network, non-patent document 2).

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

3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) Physical Layer procedures (Release 8), 3GPP TS36.213 v8.8.0 (2009-09) URL: http: // www.3gpp.org/ftp/Specs/2011-06/Rel-8/36_series/ 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

  However, in a heterogeneous network, when a large number of pico cells using the same frequency are arranged in a macro cell, and interference occurs between a plurality of cells, the indicator OI or the indicator HII extends over a plurality of base station apparatuses that cause interference. When inter-cell interference is controlled by this, the opportunity for each base station apparatus to transmit to a mobile station apparatus connected to the own station is extremely limited, and there is a problem if frequency utilization efficiency and throughput cannot be sufficiently improved.

  The present invention has been made in view of the above circumstances, and a communication system, a communication method, and a base station apparatus capable of improving frequency utilization efficiency and throughput even when inter-cell interference occurs between cells of a plurality of base station apparatuses. It is another object of the present invention to provide a mobile station 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 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, A communication system that performs communication using a propagation path between the base station device and the mobile station device, wherein the main base station device is connected to each of the plurality of base station devices. A weight coefficient control unit that calculates a transmission weight coefficient multiplied by transmission data transmitted by the apparatus and a reception weight coefficient multiplied by the transmission data received by the plurality of base station apparatuses; The station device receives a transmission unit that transmits information related to the transmission weight coefficient to the mobile station device, and the mobile station device to which the station device is connected receives a transmission signal obtained by multiplying the transmission data by the transmission weight factor. Department and An interference suppression unit that multiplies the transmission data by the transmission weighting factor and the reception weighting factor, and the mobile station apparatus determines the transmission signal by multiplying the transmission data by the transmission weighting factor. , And a transmission section for transmitting to the base station apparatus to which each is connected.

  Further, the plurality of base station devices of the communication system of the present invention includes a control signal generation unit that generates a control signal having an area for storing information on the transmission weight coefficient, and the transmission unit of each base station device includes: The control signal is transmitted to the mobile station apparatus to which each is connected.

  The master base station apparatus of the communication system according to the present invention includes an upper layer that notifies the slave base station apparatus of the transmission weight coefficient and the reception weight coefficient.

  In the communication system of the present invention, the transmission weight coefficient information is a transmission weight coefficient that is multiplied by the transmission signal transmitted by the mobile station apparatus. Further, the transmission weight coefficient information is a codebook index corresponding to a transmission weight coefficient to be multiplied with respect to the transmission signal transmitted by the mobile station apparatus.

  Further, the mobile station apparatus of the communication system according to the present invention includes a control signal detection unit that detects the transmission weight coefficient from the codebook index.

  The plurality of base station devices of the communication system of the present invention further includes a reference signal generation unit that generates a reference signal multiplied by the transmission weighting factor, and the transmission units of the base station devices are respectively The reference signal is transmitted to the mobile station apparatus to which is connected.

  Further, the reference signal in the communication system of the present invention is a part of a reference signal unique to the mobile station apparatus. The reference signal in the communication system of the present invention is a part of a reference signal specific to a cell that is a connectable range of the base station apparatus. The reference signal in the communication system of the present invention is a reference signal specific to the mobile station apparatus or a reference signal specific to the cell of the base station apparatus.

  The communication method of the present invention comprises 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, A communication method in a communication system that performs communication using a propagation path between the plurality of base station apparatuses and the mobile station apparatus, wherein each of the plurality of base station apparatuses is connected in the main base station apparatus. A calculation step of calculating a transmission weight coefficient to be multiplied by transmission data transmitted by the mobile station apparatus and a reception weight coefficient to be multiplied by the transmission data received by the plurality of base station apparatuses; In the base station apparatus, a transmission step of transmitting information on the transmission weight coefficient to the mobile station apparatus, and the mobile station apparatus connected to the base station apparatus multiplies the transmission data by the transmission weight coefficient. A reception step of receiving the transmitted signal; and an interference suppression step of multiplying the transmission signal by multiplying the transmission data by the transmission weight factor, and multiplying the transmission data by the reception weight factor. A transmission step of transmitting the transmission signal multiplied by a transmission weighting factor to the base station apparatus to which the transmission signal is connected is performed.

  The communication method according to the present invention includes a control signal generation step in which the plurality of base station apparatuses generate a control signal having an area for storing information on the transmission weight coefficient, and the transmission unit of each base station apparatus includes: And a transmission step of transmitting the control signal to the mobile station apparatus to which each is connected.

  The communication method of the present invention is characterized in that the master base station device performs a notification step of notifying the slave base station device of the transmission weight coefficient and the reception weight coefficient.

  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. A base station apparatus in a communication system that performs communication using a propagation path between the plurality of base station apparatuses and the mobile station apparatus, wherein the base station apparatus is connected to each of the plurality of base station apparatuses. A weighting factor control unit that calculates a transmission weighting factor to be multiplied by transmission data transmitted by the mobile station device and a reception weighting factor to be multiplied to the transmission data received by the plurality of base station devices; A transmission unit that transmits information related to the transmission weight coefficient to the mobile station device; and a reception unit that receives a transmission signal obtained by multiplying the transmission data by the transmission weight factor by the mobile station device to which each is connected, Said sending An interference suppression unit that multiplies the transmission signal by data with the transmission weighting factor and the reception weighting factor; a control signal generation unit that generates a control signal having an area for storing information on the transmission weighting factor; and the transmission And an upper layer that notifies the weighting factor and the reception weighting factor.

  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. , A mobile station apparatus in a communication system that performs communication using propagation paths between the plurality of base station apparatuses and the mobile station apparatus, wherein the mobile station apparatus includes the main base station apparatus and the propagation path. And a precoding that generates a transmission signal obtained by multiplying the transmission data transmitted by the mobile station apparatus by the transmission weight coefficient. And a transmission unit that transmits the transmission signal multiplied by the transmission weight coefficient to the base station apparatus to which the transmission signal is connected.

  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.

<First Embodiment>
In the communication system 1 according to the first embodiment, the base station apparatus 100-k and the mobile station apparatus 200-j perform DFT-s-OFDM (discrete Fourier transform-spread-Orthogonal Division Division Multiplexing; discrete Fourier transform spread orthogonal frequency). An example in which data transmission is performed using the division multiplexing method will be described. The present embodiment is not limited to this, but other transmission schemes such as single carrier transmission scheme such as SC-FDMA (single carrier-frequency division multiple access), OFDM (orthogonal) Multi-carrier transmission schemes such as frequency division multiplexing (MC) and multiple carrier-code division multiple access (MC-CDMA) 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 apparatuses 100-k (k is an arbitrary positive integer, k = 1 to 3 in FIG. 1), and a plurality of mobile station apparatuses 200- j (j is an arbitrary positive integer, j = 1 to 3 in FIG. 1).

  A plurality of base station apparatuses 100-k and a plurality of mobile station apparatuses 200-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-j in the communication system 1 includes a mobile station device connected to a cooperating base station device and a mobile station device that is a target of cooperation.

  Each base station apparatus 100-k is arranged in such a configuration that its own cell overlaps with a part of the cell of another base station apparatus or partially overlaps and uses the same frequency repeatedly in one cell. Has been. Each base station apparatus 100-k is connected by backhaul lines 10-1, 10-2 (for example, X2 interface) using optical fibers, Internet lines, radio lines or the like.

Between the base station apparatus 100-k and the mobile station apparatus 200-j is represented by an uplink 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-j is wirelessly connected to the base station device 100-k where k = j. That is, in mobile station apparatus 200-j, a signal transmitted by base station apparatus 100-k where k ≠ j is inter-cell interference.

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

As will be described in detail later, each mobile station apparatus 200-j can suppress inter-cell interference that the base station apparatus 100-k and the mobile station apparatus 200-j can cooperate with each other in the transmission signal transmitted by itself. The transmission weight coefficient V _j is multiplied. Also, each base station apparatus 100-k, the base station apparatus 100-k and the mobile station apparatus 200-j is in concert, multiplies the reception signal received weighting factor U _k that can suppress inter-cell interference that can have mutually 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) has a plurality of receiving antenna units 101-L (L is an arbitrary positive integer, and represents the number of each part hereinafter), Receiving section 102-L, propagation path estimation section 103, GI removal section 104-L, DFT section 105-L, interference suppression section 106, propagation path compensation section 107, IDFT section 108, demodulation section 109, decoding section 110, weight coefficient The control unit 111, the upper layer 112, the control signal detection unit 113, the control signal generation unit 121, the reference signal generation unit 122, the transmission unit 123, and the transmission antenna unit 124 are configured. In addition, in FIG. 2, although the base station apparatus 100-1 shows an example in case of providing two (L = 2) receiving antenna parts, it is not limited to this, You may provide how many antennas. Moreover, although it is one transmission antenna part, it is not restricted to this, A several transmission antenna part may be provided, and it is good also as a structure which shares a transmission antenna part and a reception antenna part. Further, when a part or all of the base station apparatus 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.

  Upper layer 112 acquires propagation path information from slave base station devices (base station device 100-2 and base station device 100-3) through backhaul lines 10-1 and 10-2. Further, the upper layer 112 outputs the propagation path information to the weight coefficient control unit 111. 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.

In addition, the upper layer 112 transmits propagation path information (information on the propagation path H _2j ) between the mobile station apparatus 200-j and the base station apparatus 100-2 from the base station apparatus 100-2 through the backhaul line 10-1. get. In addition, the upper layer 112 acquires propagation path information (information on the propagation path H _3j ) between the mobile station apparatus 200-j and the base station apparatus 100-3 from the base station apparatus 100-3 through the backhaul line 10-2. To do.

  Also, the upper layer 112 acquires the reception weight coefficient of the slave base station apparatus calculated by the weight coefficient control unit 111 described later and the transmission weight coefficient of the mobile station apparatus connected to the slave base station apparatus.

  Further, the upper layer 112 notifies each slave base station apparatus of the reception weight coefficient of the slave base station apparatus and the transmission weight coefficient of the mobile station apparatus connected to the slave base station apparatus via the backhaul line 10-1.

Specifically, the upper layer 112 of the base station 100-1, a transmission weight factor _{V 2} to be multiplied by the transmission signal of the mobile station device 200-2 multiplies the received signal of the base station device 100-2 and a reception weighting factor _{U 2,} and notifies the base station device 100-2 via the backhaul 10-1. Further, the upper layer 112 of the base station 100-1, a transmission weight factor _{V 3} to be multiplied by the transmission signal of the mobile station device 200-3, the reception weighting factors to be multiplied to the received signal of the base station device 100-3 and U _3, notifies the base station apparatus 100-3 via the backhaul 10-2.

  Further, the upper layer 112 outputs control data such as MCS (Modulation and Coding Scheme) of the transmission signal transmitted by the mobile station apparatus 200-2 and the number of spatial multiplexing to the control signal generation unit 121. The control data is set in consideration of the propagation path estimation value, the transmission weight coefficient, and the reception weight coefficient. The upper layer 112 also notifies other parameters necessary for each part of the base station device 100-1 to perform its function.

  The control signal generation unit 121 generates a control signal including control data output from the higher layer 112 and a transmission weight coefficient by which the mobile station apparatus connected to the own station multiplies the transmission signal. The control signal corresponds to, for example, a downlink control channel (PDCCH; Physical Uplink Control Channel) in LTE. Also, the transmission weighting factor can be reported using a downlink common channel (PDSCH) in LTE. 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 121. The control signal has an area for storing transmission weight coefficient information of the mobile station apparatus connected to the own station. As shown in FIG. 3, the region for storing information about the transmission weight factor of the reception weighting factor V ₁ to the mobile station device 200-1 multiplies the transmission signal is provided. The MCS area and the layer area are examples of control data included in addition to the information related to the transmission weight coefficient, and may include other control data. The MCS area is an area for storing MCS information of a signal transmitted from the mobile station apparatus 200-1 to the base station apparatus 100-1. A layer area | region is an area | region where the information regarding the spatial multiplexing number of the signal which the mobile station apparatus 200-1 transmits to the base station apparatus 100-1 is stored. Note that a control signal generation unit that generates a control signal including a weighting factor may be referred to as a weighting factor information generation unit, and a control signal including the weighting factor generated by the control signal generation unit may be referred to as weighting factor information.

  The reference signal generation unit 122 generates a reference signal (pilot signal). The reference signal is, for example, a signal used to estimate propagation characteristics from the transmission antenna unit 124 of the base station device 100-1 to each reception antenna unit of the mobile station device. 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 transmission unit 123 up-converts the downlink signal including the control signal output from the control signal generation unit 121 and the reference signal to a frequency band where transmission is possible, and connects to the base station connected via the transmission antenna unit 124. It is transmitted to the station apparatus 100-k. Note that the transmission unit 123 can apply the transmission method so that the mobile station device 200-j can receive in the downlink of the communication system 1. For example, in LTE, OFDM transmission is applicable.

  The base station device 100-1 receives the transmission signal of the mobile station device 200-j via the reception antenna unit 101-L. Here, transmission signals other than the mobile station device 200-1 cause inter-cell interference. The configuration of the mobile station apparatus that generates the transmission signal will be described later.

  The receiving unit 102-L downconverts the radio frequency signal input from the receiving antenna unit 101-L into a frequency band that can be processed by digital signals, and further performs filtering processing on the downconverted signal to perform unnecessary components (spurious; Remove Spurous). The receiving unit 102-L 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 103 and a GI removal unit. 104-L and the control signal detection unit 113.

  The GI removal unit 104-L removes the guard interval GI from the signal output from the reception unit 102-L in order to avoid distortion due to the delayed wave, and outputs the removed signal to the DFT unit 105-L.

  The DFT unit 105-L performs Discrete Fourier Transform (DFT: Discrete Fourier Transform), which converts the signal from which the guard interval GI input from the GI removal unit 104-L is removed, from a time domain signal to a frequency domain signal, and performs interference. The result is output to the suppression unit 106. Note that the DFT unit 105-L 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 control signal detection unit 113 detects a control signal included in the signal output from the reception unit 102-2. As the control signal, for example, feedback information such as CQI (Channel Quality Control) in LTE corresponds. When the control signal detection unit 113 extracts the feedback information, the control signal detection unit 113 outputs the feedback information to the control signal generation unit 121 and the upper layer 112.

  The control signal generation unit 121 and the upper layer 112 generate a downlink transmission signal (downlink information data, control signal) in consideration of feedback information such as the CQI.

  The propagation path estimation unit 103 performs propagation path estimation using the reference signal included in the signal output from the reception unit 102-L. Then, the propagation path estimation unit 103 notifies the propagation path estimation value to the propagation path compensation unit 107, the weight coefficient control unit 111, and the upper layer 112. The propagation path estimated value is, for example, a transfer function, an impulse response, or the like.

The weighting coefficient control unit 111 uses the propagation path information (propagation path estimation value) acquired from the upper layer 112 and the transmission path estimation unit 103, and multiplies the transmission weight coefficient V _j by which the signal transmitted from the mobile station apparatus 200-j is transmitted. In addition, a reception weight coefficient U _k to be multiplied with the reception signal of the master base station apparatus and the slave base station apparatus is calculated.

That is, the master base station apparatus acquires propagation path estimated values between all base station apparatuses (master base station apparatus and slave base station apparatus) that perform cooperative control and all mobile station apparatuses that participate in the cooperative control. The transmission weight coefficient V _j of the mobile station apparatus and the reception weight coefficient U _k of the base station apparatus are calculated using the propagation path estimation value.

ここで、Ｈ_ｋｊは、移動局装置２００−ｊと、協調制御の対象である基地局装置１００−ｋとの間の伝搬路行列、Ｖ_ｊは移動局装置２００−ｊの送信重み係数のベクトル、Ｕ_ｋは基地局装置１００−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。 As an example, the weighting factor control unit 111 is such that the direction (vector) of an equivalent propagation path of interference signals coming from a plurality of mobile station devices serving as interference sources is orthogonal to the reception weighting factor by which each base station device multiplies the reception signal. Thus, the transmission weighting coefficient is calculated (Equation 1).

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

Further, the weight coefficient control unit 111 notifies the upper layer 112 of the reception weight coefficient U _k of the slave base station apparatus and the transmission weight coefficient V _j of the mobile station apparatus connected to the slave base station apparatus. Also, the weight coefficient control unit 111 outputs a reception weight coefficient U ₁ to be multiplied to the reception signal of the master base station apparatus (own station) to the interference suppression unit 106. Further, the weight coefficient control unit 111 outputs the transmission weight coefficient V ₁ of the mobile station apparatus connected to the master base station apparatus (own station) to the control signal generation unit 121. The weight coefficient control unit 111 and the weight coefficient control function described above may be included in the upper layer 112.

  The interference suppression unit 106 multiplies the frequency domain signal input from the DFT unit 105 -L by the reception weight coefficient input from the weight coefficient control unit 111.

  Based on the propagation path estimation value input from the propagation path estimation unit 103, the propagation path compensation unit 107 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 107 performs propagation path compensation by multiplying the signal input from the interference suppression unit 106 by this weight coefficient.

  The IDFT unit 108 performs an IDFT (Inverse Discrete Fourier Transform) process on the signal output from the propagation path compensation unit 107.

  Demodulation section 109 performs demodulation processing on the signal input from IDFT section 108. 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 110 performs error correction decoding processing on the encoded bit sequence (or encoded bit LLR) after demodulation output from the demodulation unit 109, calculates information data transmitted to itself, To 112. This error correction decoding processing method is a method corresponding to error correction coding such as turbo coding and convolution coding performed by a connected base station apparatus. The error correction decoding process can be applied to either hard decision or soft decision.

  When mobile station apparatus 200-j transmits interleaved data modulation symbols, decoding section 110 decodes the input coded bit sequence corresponding to the interleaving before performing error correction decoding processing. Process. Then, decoding section 110 performs error correction decoding processing on the signal that has been subjected to deinterleaving processing.

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 weight coefficient control unit 111 calculates the transmission weight coefficient V _j and the reception weight coefficient U _k .

In the calculation method of FIG. 4, the complex conjugate transpose matrix of the propagation path matrix from the mobile station apparatus to the base station apparatus is
Using the property (reciprocity of propagation path) that the base station apparatus becomes the propagation path matrix of the mobile station apparatus, processing to find the weighting coefficient that minimizes the influence of interference while switching the roles of transmission and reception Repeat.

First, when the weight coefficient control unit 111 acquires the propagation path information, the weight coefficient control unit 111 sets an arbitrary transmission weight coefficient V _j (S100).

Next, the weighting factor control unit 111 calculates the sum _{Qk, i} of interference received by the base station apparatus 100-k based on (Equation 2) (S101). Here, Q is a covariance matrix of the received interference signal. P is the transmission power, and K is the number of base station apparatuses that cooperate and suppress inter-cell interference. _H represents complex conjugate transposition.

Then, the weighting factor controller 111, the sum _{Q k} of the calculated _{interference,} and singular value decomposition _i, sum _{Q k} of the _{interference,} the receiving weight coefficients _{U k} for suppressing _i, calculates a _i (S102). In step S102 and step S103, the reception weight coefficient U _k is calculated when the base station apparatus 100-k receives the transmission signal of the mobile station apparatus 200-j.
Next, the roles of transmission and reception of the mobile station device 200-j and the base station device 100-k are switched (S103). That is, the case where base station apparatus 100-k receives the mobile station apparatus 200-j is a transmission signal multiplied by the coefficient _{U k, i,} and calculates the reception weight coefficient _U ^{k ~} of the mobile station apparatus 200-j . The reception weight coefficient U _k ^˜ corresponds to the transmission weight coefficient V _k of the mobile station device 200-j.

The reception weighting coefficient _U ^k is calculated ^in-first calculates based sum _{Q j} of interference mobile station apparatus 200-j _receives, ^{i ~} to (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). The roles of transmission and reception of the mobile station device 200-j and the base station device 100-k are switched again (S106). In other _words, substituting _{V k, i = U k,} i ~ a.

  A counter (not shown) for counting the number of processes is incremented by one (S107), and the processes of steps S101 to S106 are repeated until a predetermined number of times I is reached (S108, N). 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 ^˜ ) are repeatedly updated so that the interference power is reduced while switching the roles of transmission and reception of the base station device 100-k and the mobile station device 200-j. As a result, a reception weighting coefficient that allows the base station apparatus 100-k and the mobile station apparatus 200-j to suppress the influence of interference is obtained.

Then, by using the reception weight coefficient U _k ^˜ where k = j as the transmission weight coefficient V _j of the mobile station apparatus 200-j, a plurality of base station apparatuses 100-k cooperate to suppress the influence of interference. Can do. 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.

  As shown in FIG. 5, the slave base station devices (base station devices 100-2 and 100-3) have a plurality of receiving antenna units 101-L (L is an arbitrary positive integer and represents the number of each part. ), Receiving section 102-L, propagation path estimating section 103, GI removing section 104-L, DFT section 105-L, interference suppressing section 106, propagation path compensating section 107, IDFT section 108, demodulating section 109, decoding section 110, An upper layer 152, a control signal detection unit 113, a control signal generation unit 121, a reference signal generation unit 122, a transmission unit 123, and a transmission antenna unit 124 are configured. In addition, in FIG. 5, although the base station apparatus 100-2 shows an example in the case of providing two (L = 2) receiving antenna parts, it is not limited to this, You may provide how many antennas. Moreover, although it is one transmission antenna part, it is not restricted to this, A several transmission antenna part may be provided, and it is good also as a structure which shares a transmission antenna part and a reception antenna part. Further, when a part or all of the base station device 100-2 is formed into a chip to form an integrated circuit, it has a chip control circuit (not shown) for controlling each functional block.

  Compared with base station apparatus 100-1, operation in higher layer 152 in base station apparatus 100-2 is different. Hereinafter, mainly different parts will be described.

Upper layer 152 acquires propagation path estimation value H _2j between mobile station apparatus 200-j and its own station (base station apparatus 100-2) from propagation path estimation section 103. Upper layer 152 notifies channel estimation value H _2j to base station apparatus 100-1 via backhaul line 10-1.

Further, the upper layer 152 sets the transmission weight coefficient V ₂ of the transmission signal of the mobile station apparatus 200-2 connected to the own station and the reception weight coefficient U ₂ to be multiplied to the reception signal of the own station to the backhaul line 10- 1 from the base station apparatus 100-1. The transmission weight coefficient V ₂ and the reception weight coefficient U ₂ are calculated by the weight coefficient control unit 111 of the base station apparatus 100-1.

In addition, the upper layer 152 inputs the reception weight coefficient U ₂ to the interference suppression unit 106. Interference suppression unit 106 multiplies the received weighting factor _{U 2} into a frequency domain signal inputted from DFT105-L.

Further, the upper layer 152 inputs the transmission weight factor V ₂ of the mobile station apparatus 200-j that is connected to the own station is multiplied to the transmission signal to the control signal generator 121.

Control signal generating unit 121 generates a control signal including the control data and the transmission weight factor V ₂ the upper layer 152 outputs. Note that the format shown in FIG. 3 can be applied to the format of the control signal, similarly to the master base station apparatus 100-1. The control data includes MCS information, spatial multiplexing number, and the like.

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

  As illustrated in FIG. 6, the mobile station apparatus 200-j includes an upper layer 201, an encoding unit 202, a modulation unit 203, a DFT unit 204, a precoding unit 205, a reference signal generation unit 206, a control signal generation unit 207, a resource A mapping unit 208, an IDFT unit 209, a GI insertion unit 210, a transmission unit 211, a transmission antenna unit 212, a reception antenna unit 221, a reception unit 222, a control signal detection unit 223, and a propagation path estimation unit 224 are configured. When a part or all of the mobile station device 200-j is formed into a chip to form an integrated circuit, it has a chip control circuit (not shown) that controls each functional block.

The receiving unit 222 of the mobile station device 200-j receives the downlink transmission signal of the base station device 100-k with j = k via the receiving antenna unit 221. The transmission signal is a signal including a control signal such as a transmission weight coefficient. The control signal is a signal including the transmission weight coefficient V _j generated by the control signal generation unit 121 of the base station apparatus 100-k. Although details will be described later, the transmission weight coefficient V _j is multiplied by the transmission signal of the mobile station apparatus 100-j.

  The receiving unit 222 down-converts (radio frequency conversion) the signal output from the receiving antenna unit 221 to a frequency band where digital signal processing such as signal detection processing can be performed, and further performs filtering processing to remove spuriousness, The filtered signal is converted from an analog signal to a digital signal (Analog to Digital conversion).

  The propagation path estimation unit 224 performs propagation path estimation using the reference signal included in the signal output from the reception unit 222. The propagation path estimation is for estimating a propagation path between the base station apparatus 100-k and the mobile station apparatus 200-j in the downlink.

The control signal detection unit 223 performs propagation path compensation, demodulation processing, decoding processing, and the like on the control signal output from the reception unit 222, and extracts a transmission weight coefficient _Vj . The control signal detection unit 223 uses the result of propagation channel estimation (propagation channel estimation value) by the propagation channel estimation unit 224 for propagation channel compensation, demodulation processing, and decoding processing.

  In addition, the control signal detection unit 223 extracts feedback information such as MCS information (Modulation and Coding Scheme) of the transmission signal of the mobile station device 100-j and the number of spatial multiplexing.

The upper layer 112 acquires the transmission weight coefficient V _j included in the control signal. The upper layer 112 also acquires feedback information such as MCS information and spatial multiplexing number included in the control signal.

  Further, upper layer 112 outputs information data to be transmitted on the uplink to encoding section 202 based on the feedback information. 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 upper layer 112 outputs control data (including MCS information, the number of spatial multiplexing, etc.) to be transmitted on the uplink. The upper layer 201 also notifies other parameters necessary for each part of the mobile station device 200-j to perform its function.

  The encoding unit 202 performs error correction encoding on the information data input from the upper layer 201. Examples of the encoding scheme used when the encoding unit 202 performs error correction encoding include turbo encoding, convolutional encoding, and low density parity check encoding; LDPC).

  Note that the encoding unit 202 performs rate matching processing on the encoded bit sequence in order to match the coding rate of the data sequence subjected to error correction encoding with the encoding rate corresponding to the data transmission rate. May be. In addition, the encoding unit 202 may have a function of rearranging and interleaving the error correction encoded data series.

  Modulation section 203 modulates the signal input from encoding section 202 to generate a modulation symbol. The modulation processing performed by the modulation unit 203 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). Note that the modulation unit 203 may have a function of rearranging generated modulation symbols and interleaving them.

  The DFT unit 204 performs DFT processing (discrete Fourier transform processing) on the modulation symbol output from the modulation unit 203.

  Precoding section 205 multiplies the output signal of DFT section 204 by a transmission weight coefficient. As shown in FIG. 6, the precoding unit 205 acquires the transmission weighting factor via the higher layer 201, but may be configured to acquire directly from the control signal detection unit 223.

  The reference signal generation unit 206 generates a reference signal (pilot signal) and outputs the generated reference signal to the resource mapping unit 208. The reference signal is a signal used to estimate the propagation characteristics from the transmitting antenna of the mobile station device 200-j to each receiving antenna of the base station device 100-k in the base station device 100-k. 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 base station apparatus 100-k.

  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 207 generates a control signal including downlink control data output from the higher layer 201. For example, CQI (Channel Quality Control) in LTE is applicable. The control signal may be subjected to error correction coding and modulation processing.

The resource mapping unit 208 maps modulation symbols, reference signals, and control signals to resource elements based on scheduling information notified from the upper layer 201 (hereinafter referred to as resource mapping). The resource element is a minimum unit for arranging a signal composed of one subcarrier and one OFDM symbol.
The IDFT unit 209 performs inverse discrete Fourier transform (IDFT) on the frequency domain signal input from the resource mapping unit 208 to convert it into a time domain signal. The IDFT unit 209 may be configured to 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.

  The GI insertion unit 210 adds a 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 the IDFT unit 209 and generates an SC-FDMA symbol. The guard interval GI is intended to allow the receiving side (base station apparatus 100-k) to maintain the periodicity and perform DFT processing (DFT unit 105-l of the base station apparatus 100-k). This is the section to add. For example, the GI insertion unit 210 prepends a copy (copy) of a part of the latter half of the effective symbol as the guard interval GI to the effective symbol. Therefore, the effective symbol preceded by the guard interval GI is the SC-FDMA symbol.

  The transmission unit 211 performs D / A (digital-to-analog) conversion on the SC-FDMA symbol input from the GI insertion unit 210 to generate an analog signal. The transmission unit 211 generates a band limited signal by performing band limitation on the generated analog signal by filtering processing. The transmission unit 211 up-converts the generated band limited signal to a radio frequency band and outputs the signal to the transmission antenna unit 212.

  Next, the process of the interference suppression unit 106 in the base station apparatus 100-k that has received the transmission signal of the mobile station apparatus 200-j (j = 1 to 3) will be specifically described. The following is an example when the base station apparatus has two antennas (L = 2).

ここで、Ｒ_ｋ、Ｌは基地局装置ｋのＤＦＴ部１０５−Ｌから入力される信号、Ｈ_ｋｊ、Ｌは移動局装置２００−ｊ（ｊ＝１〜３）の送信信号を基地局装置１００−ｋがアンテナ部１０１−Ｌを介して受信した場合の伝搬路（伝達関数）、Ｖ_ｊは移動局装置２００−ｊの送信信号に乗算されている送信重み係数（各移動局装置のプレコーディング部２０５で乗算）、Ｓ_ｊは移動局装置２００−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 base station apparatus 100-k, when the signal input from DFT section 105-1 and DFT section 105-2 to interference suppression section 106 is vector R _k , it can be expressed as (Equation 4).

Here, R _{k and L} are signals input from the DFT unit 105- _L of the base station apparatus k, H _{kj and L} are transmission signals of the mobile station apparatus 200-j (j = 1 to 3), and the base station apparatus 100. channel when -k is received via the antenna unit 101-L (transfer function), V _j is the transmission weight factor that is multiplied to the transmission signal of the mobile station apparatus 200-j (precoding of each mobile station apparatus S _j is a data modulation symbol of mobile station apparatus 200-j. Further, + (represented by a circle plus in Equations 4 and 5) is addition for each element.

If the interference suppression unit 106 multiplies the R _k by the reception weight coefficient U _k as Y _K , it can be expressed as (Equation 5). Here, U _{k and L} are reception weight coefficients for multiplying the signal input from the DFT section 105-L.

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-j.

  First, the mobile station device 200-j transmits a reference signal to the master base station device and the slave base station device (S201, S202).

The master base station apparatus and slave base station apparatus that have received the reference signal in steps S201 and S202 use the reference signal to estimate the propagation path between the local station and the mobile station apparatus 200-j (S203, S204). ). In the communication system 1, the base station device 100-k estimates the propagation path H _k1 , the propagation path H _k2, and the propagation path H _k3 .

  Further, the slave base station apparatus notifies the master base station apparatus of the result of propagation path estimation (propagation path information) (S205).

  Next, the master base station apparatus calculates a transmission weight coefficient and a reception weight coefficient using the propagation path information (S206).

Further, the master base station apparatus notifies the slave base station apparatus of the calculated transmission weight coefficient V _j and reception weight coefficient U _k via the backhaul line (S207).

Further, the slave base station apparatus notifies the transmission weight coefficient V _j to each mobile station apparatus to which the own station 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 transmission weight factor _{V 2} from the master base station device 100-1 become.

  Further, the master base station apparatus directly transmits the transmission weight coefficient of the mobile station apparatus connected to the own station to the mobile station apparatus (S209).

  Subsequently, each mobile station apparatus multiplies its own information data to be transmitted by a transmission weight coefficient (S210), and transmits the multiplied information data (S211 and S212).

As described above, in the first embodiment, in the communication system 1 in which the cells of the plurality of base station devices 100-k are arranged so that all or some of them overlap, the master base station device Transmission weight coefficient V _{j of} each mobile station apparatus 200-j so that the direction of the equivalent propagation path of the interference signal received by apparatus 100-k is orthogonal to the reception weight coefficient by which base station apparatus 100-k multiplies the received signal. And the reception weight coefficient U _k of the base station apparatus 100- _k is calculated.

Then, base station apparatus 100-k notifies transmission weight coefficient V _j to mobile station apparatus 200-j connected to the own station, and mobile station apparatus 200-j multiplies the transmission signal by transmission weight coefficient V _j. To perform transmission 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 part of the cells, this is caused when a 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 weight coefficient control unit 111 of the base station apparatus 100-1 may be included in the upper layer 112. Further, the weight coefficient control unit 111 may be included in a base station management unit that is located outside the cooperating base station devices 100-k and controls these base station devices 100-k.

<Second Embodiment>
In the second embodiment, in the communication system 1 in which the plurality of base station apparatuses 100-k 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 _k notifies the transmission weight coefficient U _k to the mobile station apparatus 200-j 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-k 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-j Are configured to share at least the code book of the reception weight coefficient U _k of the mobile station apparatus 200-j.

An example of the code book is shown in FIG. In FIG. 8, the transmission weight coefficient V _{j, n} is the nth transmission weight coefficient candidate in the j-th mobile station apparatus (j and n are arbitrary positive integers). Further, the reception weighting coefficient U _{k, n} is the nth reception weighting coefficient candidate in the kth base 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 four base station apparatuses and 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 apparatus 100-1 holds the code book in the weight coefficient control unit 111. First, the weight coefficient control unit 111 selects codebook candidates from the number of cooperating base station apparatuses and the number of mobile station apparatuses input from the upper layer 112.

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

Next, the weighting factor control unit 111 uses the propagation path information H _kj input from the propagation path estimation unit 103 and the upper layer 112 and the selected codebook index # candidate to minimize the influence of interference. A process for obtaining such a weighting coefficient 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 (Equation 2) and (Equation 3), and the total interference Q _{k, i} and the sum Q _{j, i} ^~ selects a codebook index # to be minimized.

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 transmission weight coefficient” (S208 and S209) in FIG. 7 are replaced with “Codebook index notification”.

  Next, the format of the control signal output by the control signal generator 121 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 121.

The control signal has a codebook index # area for notifying information on the transmission weight coefficient UV _j of the mobile station apparatus connected to the own station. 9, as an example, shows a case where the mobile station device 200-1 is provided 4-bit codebook index corresponding to the transmission weight factor V ₁ to be multiplied by the transmission signal as an area for storing information about the transmission weight factor Yes.

Similarly, the control signal generation unit 121 of the slave base station apparatus notifies the transmission weight coefficient V _j to the mobile station apparatus 200-j in the format of the control signal shown in FIG.

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

<Third Embodiment>
In the third embodiment, in the communication system 1a in which a plurality of base station apparatuses 300-k cooperate to suppress inter-cell interference, the base station apparatus 300-k uses a plurality of reference signals to cause the mobile station apparatus 400- A mode in which a method for notifying j of the transmission weighting factor V _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. As shown in FIG. 11, the master base station apparatus (base station apparatus 300-1) receives a plurality of reception antenna units 101-L (hereinafter, L is an arbitrary positive integer and represents the number of each part), Unit 102-L, channel estimation unit 103, GI elimination unit 104-L, DFT unit 105-L, interference suppression unit 106, channel compensation unit 107, IDFT unit 108, demodulation unit 109, decoding unit 110, weight coefficient control Unit 111, upper layer 112, control signal detection unit 113, control signal generation unit 121, reference signal generation unit 322, transmission unit 123, and transmission antenna unit 124. In addition, in FIG. 11, although an example in case the base station apparatus 300-1 is provided with two (L = 2) receiving antenna parts is shown, it is not limited to this, You may provide how many antennas. Moreover, although it is one transmission antenna part, it is not restricted to this, A several transmission antenna part may be provided, and it is good also as a structure which shares a transmission antenna part and a reception antenna part. Further, when a 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 reference signal generation unit 322 is different. Hereinafter, these parts will be mainly described.

Reference signal generating unit 322, a first reference signal used for estimating the propagation characteristic to each receive antenna of the mobile station apparatus 400-k from the transmission antenna of the base station apparatus 300-j, the transmission weight factor V ₁ A second reference signal used for notifying the mobile station apparatus is generated. The transmission transmission weight coefficient V ₁ is input from the weight coefficient control unit 111 to the reference signal generation unit 322. Second reference signal is generated by multiplying a transmission weight factor V 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 predetermined known code sequences in communication systems 1a and _{S RS,} the first reference _signal, becomes _{S RS,} the second reference _signal, the V _{1 S RS.} The code sequence may be an orthogonal sequence, such as a Hadamard code or a CAZAC (Constant Amplitude Zero Auto-Correlation) sequence.

  The transmission unit 123 has a function of performing resource mapping of the first reference signal, the second reference signal, and the control signal to resource elements. Then, the transmission unit 123 up-converts a signal including the control signal output from the control signal generation unit 121, the first reference signal, and the second reference signal to a frequency band that can be transmitted in the downlink, and a transmission antenna unit It transmits to the connected base station apparatus via 124.

  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.

  As shown in FIG. 12, the slave base station devices (base station devices 300-2 and 300-3) have a plurality of reception antenna units 101-L (L is an arbitrary positive integer and represents the number of each part. ), Receiving section 102-L, propagation path estimating section 103, GI removing section 104-L, DFT section 105-L, interference suppressing section 106, propagation path compensating section 107, IDFT section 108, demodulating section 109, decoding section 110, An upper layer 152, a control signal detection unit 113, a control signal generation unit 121, a reference signal generation unit 352, a transmission unit 123, and a transmission antenna unit 124 are configured. In addition, in FIG. 12, although an example in case the base station apparatus 300-2 is provided with two (L = 2) receiving antenna parts is shown, it is not limited to this, You may provide how many antennas. Moreover, although it is one transmission antenna part, it is not restricted to this, A several transmission antenna part may be provided, and it is good also as a structure which shares a transmission antenna part and a reception antenna part. Further, 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) for controlling 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 reference signal generation unit 352 is different. Hereinafter, these parts will be mainly described.

The reference signal generation unit 352 uses the first reference signal used for estimating the propagation characteristics from the transmission antenna of the base station apparatus to the reception antenna of each mobile station apparatus, and the transmission weight coefficient V ₂ as the mobile station apparatus 400-2. And a second reference signal used for notifying.

For example, when a known code sequence previously determined in the communication system 1a and _{S RS,} the first reference signal _{S RS,} the second reference signal is _V 2 _{S RS.} The transmission weight coefficient V ₂ is acquired from the base station apparatus 300-1 through the backhaul line 10-1 and is input via the upper layer 152.

  The transmission unit 123 has a function of performing resource mapping of the first reference signal, the second reference signal, and the control signal to resource elements. The control signal is a signal including control data such as MCS information and spatial multiplexing information of the transmission signal of the mobile station device 400-2 generated by the control signal generation unit 121. As described above, the same resource mapping format in the transmission unit 123 of the base station apparatus 300-1 can be applied as the resource mapping format.

  The transmission unit 123 up-converts a signal including the control signal output from the control signal generation unit 121, the first reference signal, and the second reference signal to a frequency band that can be transmitted in the downlink, and a transmission antenna unit It transmits to the connected base station apparatus via 124.

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

  FIG. 13 is a schematic diagram illustrating a configuration of a mobile station device 400-j according to the third embodiment. As shown in FIG. 13, the mobile station apparatus 400-j includes an upper layer 201, an encoding unit 202, a modulation unit 203, a DFT unit 204, a precoding unit 205, a reference signal generation unit 206, a control signal generation unit 207, resources A mapping unit 208, an IDFT unit 209, a GI insertion unit 210, a transmission unit 211, a transmission antenna unit 212, a reception antenna unit 221, a reception unit 222, a control signal detection unit 423, and a propagation path estimation unit 224 are configured. When a part or all of the mobile station device 400-j is formed into a chip to form an integrated circuit, it has a chip control circuit (not shown) that controls each functional block.

  In the mobile station device 400-j, the components having the same reference numbers as those in FIG. When compared with the mobile station apparatus 400-j of the third embodiment and the mobile station apparatus 200-j of the first embodiment, the control signal detection unit 423 is different. In the following, the description will be made centering on the portion.

The propagation path estimation unit 224 performs propagation path estimation using the first reference signal _SRS1 included in the signal output from the reception unit 222. Then, the propagation path estimation value (for example, transfer function) is notified to the control signal detection unit 423.

More specifically, the propagation path estimation unit 224 includes the first reference signal H _k S _RS1 output from the reception unit 222 (where H _k is the base station device 300-j (where j = k) and the mobile station device). The propagation path estimated value H ^ is calculated by dividing the propagation path between 400-k) by the known signal _SRS1 .

In addition, the propagation path estimation value of the subcarriers where the known signal S _RS1 is not arranged is an interpolation technique such as linear interpolation or FFT interpolation using the propagation path estimation value of the subcarrier where the first reference signal HS _RS1 is arranged. Can be calculated.

  The control signal detection unit 423 detects a control signal included in the signal output from the reception unit 222. When the information of the MCS and the number of layers applied to the information data included in the control signal is extracted, the higher layer 201 is notified.

Further, the control signal detection unit 423 calculates the transmission weight coefficient V _k ^ using the second reference signal S _RS2 (= V _k S _RS1 ) included in the signal output from the reception unit 222. Then, the transmission weight coefficient V _k ^ is input to the upper layer 201. The calculated transmission weight coefficient information V _k ^ can be expressed by the following (formula 6). Here, H _k ^ is a propagation path estimated value.

The precoding unit 205 multiplies the output signal of the DFT unit 204 by a transmission weight coefficient V _k ^.

  Next, resource mapping when transmitting by the transmission antenna unit 124 of the base station apparatus 300-1 according to the third embodiment will be described with reference to FIG.

In FIG. 14, the horizontal direction indicates time T, and the vertical direction indicates frequency F. The white portion RE1 is a resource element that maps a control signal and downlink information data. A thick frame range MA represents an area in which information data addressed to the mobile station apparatus to which the base station apparatus 300-1 notifies the transmission weight coefficient V _j is mapped.

  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 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 cell-specific reference signal by the transmission weight coefficient V _j , the transmission weight coefficient V _j is notified 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 when transmission is performed by the transmission antenna unit 124 of the base station device 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, an outline part RE1 is a resource element that maps a control signal and downlink information data. Range MA of bold frame represents a region where the base station apparatus 300-1 maps the information data addressed to the mobile station apparatus to notify the transmission weight factor V _j.

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 downlink information data of the mobile station apparatus that notifies the transmission weighting factor V _j 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 transmission weight coefficient V _j , the transmission weight coefficient V _j is notified to the mobile station apparatus.

  FIG. 16 is another example of resource mapping when transmission is performed by the transmission antenna unit 124 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, an outline part RE1 is a resource element that maps a control signal and downlink information data. A thick line area MA is an area MA to which information data of a mobile station apparatus that notifies a transmission 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. It is also possible to arrange the second reference signal in the painted part RE3 and arrange the second reference signal in the shaded part RE2.

Thus, by multiplying either the user-specific reference signal or the cell-specific reference signal by the transmission weight coefficient V _j , the transmission weight coefficient V _j is notified to the mobile station apparatus.

  FIG. 17 is another example of resource mapping when transmission is performed by the transmission antenna unit 124 of the base station device 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 area RE1 is a resource element that maps a control signal and downlink information data. A thick line region RB is a resource block. A resource block is a unit of resources in which a plurality of resource elements are collected, and is a minimum unit of resources to allocate downlink information data 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.

  As described above, the reference signal is either a reference signal specific to each mobile station device or a reference signal specific to a cell, and is included in a part of resource blocks in a region to which information data of the mobile station device is mapped. By multiplying the transmission weight coefficient, the mobile station apparatus is notified of the transmission 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. And since the base station apparatus notifies the mobile station apparatus of a transmission weight coefficient for suppressing inter-cell interference using the reference signal, it is possible to 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. Further, the base station apparatus can notify the weighting factor using a reference signal unique in the cell, and can construct a communication system that can efficiently transmit and receive data corresponding to the communication environment.

  In this embodiment, the method of multiplying the reference signal by the transmission weight coefficient and notifying the mobile station apparatus of the transmission weight coefficient has been described. However, the present invention is not limited to this, and the signal multiplied by the transmission weight coefficient is a known signal. If it is. For example, a control signal that is a known signal may be multiplied by a transmission weight coefficient, and the transmission weight coefficient may be 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 102-L, 222 Reception part 101-L, 221 Reception antenna part 103 Propagation path estimation part 104-L GI removal Unit 105-L DFT unit 106 interference suppression unit 107 propagation path compensation unit 108 IDFT unit 109 demodulation unit 110 decoding unit 111 weight coefficient control units 112, 152, 201 upper layer 113 control signal detection unit 121, 207 control signal generation unit 122, 206 Reference signal generators 123, 211 Transmitters 124, 212 Transmit antenna unit 202 Encoder 203 Modulator 204 DFT unit 205 Precoding unit 208 Resource mapping unit 209 IDFT unit 210 GI insertion unit 223 Control signal detection unit 224 Channel estimation Part

Claims (15)

A communication system comprising 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,
The main base station apparatus is
The transmission weight coefficient multiplied by the transmission data transmitted by the mobile station apparatus to which each of the plurality of base station apparatuses is connected using the propagation path information of the entire system, and the plurality of base station apparatuses receive the transmission weight coefficient A weight coefficient control unit for calculating a reception weight coefficient to be multiplied with the transmission data,
The plurality of base station devices are:
A transmission unit for transmitting information on the transmission weight coefficient to the mobile station device;
The mobile station apparatus to which each is connected receives a transmission signal obtained by multiplying the transmission data by the transmission weight coefficient; and
An interference suppression unit that multiplies the transmission data by the transmission weighting factor to multiply the transmission signal by the reception weighting factor,
The mobile station device
A communication system comprising: a transmission unit configured to transmit the transmission signal obtained by multiplying the transmission data by the transmission weight coefficient to the base station apparatus to which the transmission signal is connected.   The plurality of base station apparatuses include a control signal generation unit that generates a control signal having an area for storing information on the transmission weight coefficient, and the transmission units of the base station apparatuses are connected to each other. The communication system according to claim 1, wherein the control signal is transmitted to a mobile station apparatus.   The communication system according to claim 1 or 2, wherein the master base station device includes an upper layer that notifies the slave base station device of the transmission weight coefficient and the reception weight coefficient.   The communication system according to claim 3, wherein the information on the transmission weight coefficient is a transmission weight coefficient to be multiplied with the transmission signal transmitted by the mobile station apparatus.   4. The communication system according to claim 3, wherein the information on the transmission weight coefficient is a codebook index corresponding to a transmission weight coefficient to be multiplied with respect to the transmission signal transmitted by the mobile station apparatus.   The communication system according to claim 5, wherein the mobile station apparatus includes a control signal detection unit that detects the transmission weight coefficient from the codebook index.   The plurality of base station apparatuses further include a reference signal generation unit that generates a reference signal multiplied by the transmission weighting factor, and the transmission units of the base station apparatuses are connected to the mobile stations to which the respective base station apparatuses are connected. The communication system according to claim 1, wherein the reference signal is transmitted to an apparatus.   The communication system according to claim 7, wherein the reference signal is a part of a reference signal unique to the mobile station apparatus.   The communication system according to claim 7, wherein the reference signal is a part of a reference signal unique to a cell that is a connectable range of the base station apparatus.   The communication system according to claim 7, wherein the reference signal is a reference signal specific to the mobile station apparatus or a reference signal specific to the cell of the base station apparatus. A communication method in a communication system comprising 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,
In the main base station apparatus,
The transmission weight coefficient multiplied by the transmission data transmitted by the mobile station apparatus to which each of the plurality of base station apparatuses is connected using the propagation path information of the entire system, and the plurality of base station apparatuses receive the transmission weight coefficient A calculation step of calculating a reception weight coefficient to be multiplied with the transmission data;
In the plurality of base station devices,
A transmission step of transmitting information on the transmission weight coefficient to the mobile station apparatus;
A receiving step in which the mobile station apparatus to which each is connected receives a transmission signal obtained by multiplying the transmission data by the transmission weight coefficient;
An interference suppression step of multiplying the transmission signal multiplied by the transmission weighting factor and the transmission signal multiplied by the reception weighting factor,
In the mobile station device,
A communication method comprising: performing a transmission step of transmitting the transmission signal obtained by multiplying the transmission data by the transmission weight coefficient to the base station apparatus to which the transmission signal is connected.   A control signal generating step in which the plurality of base station apparatuses generate a control signal having an area for storing information on the transmission weighting coefficient; and the movement to which the transmitting unit of each base station apparatus is connected The communication method according to claim 11, wherein a transmission step of transmitting the control signal to a station apparatus is performed.   The communication method according to claim 11 or 12, wherein the primary base station apparatus performs a notification step of notifying the slave base station apparatus of the transmission weight coefficient and the reception weight coefficient. A base station apparatus in a communication system comprising 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 device
The transmission weight coefficient multiplied by the transmission data transmitted by the mobile station apparatus to which each of the plurality of base station apparatuses is connected using the propagation path information of the entire system, and the plurality of base station apparatuses receive the transmission weight coefficient A weighting factor control unit for calculating a reception weighting factor to be multiplied with transmission data;
A transmission unit for transmitting information on the transmission weight coefficient to the mobile station device;
The mobile station apparatus to which each is connected receives a transmission signal obtained by multiplying the transmission data by the transmission weight coefficient; and
An interference suppression unit that multiplies the transmission data by the transmission weighting factor to multiply the transmission signal by the reception weighting factor;
A control signal generation unit for generating a control signal having an area for storing information on the transmission weight coefficient;
An upper layer that notifies the transmission weight coefficient and the reception weight coefficient;
A base station apparatus comprising: A mobile station device in a communication system comprising 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,
The mobile station device
The main base station apparatus receives a transmission weight coefficient among transmission weight coefficients and transmission weight coefficients calculated using propagation path information of the entire system, and
A precoding unit for generating a transmission signal obtained by multiplying the transmission data transmitted by the mobile station apparatus by the transmission weight coefficient;
A transmission unit that transmits the transmission signal multiplied by the transmission weight coefficient to the base station apparatus to which each of the transmission signals is connected;
A mobile station apparatus comprising:

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