JP2013046399A - Radio communication system, radio communication device and radio communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication system capable of achieving stable MIMO communication, if a transmission path of a disabled state occurs in multi-user MIMO communication.SOLUTION: In a radio transmission device 1000, a control unit 50 calculates a weight coefficient to a transmission signal for MIMO transmission, based on channel status information from the reception side. A faulty antenna detection unit 82 detects a faulty antenna from the channel status information. A channel information repair processing unit 84 repairs an element corresponding to the faulty antenna among matrix elements of the channel status information corresponding to a transmission path matrix fed back from the receiver side, so as to supply to the control unit 50.

Description

  The present invention relates to a radio communication system in which a base station having a plurality of antennas and a terminal device exist, and more particularly to a transmission beamforming technique in a radio communication system of multi-user MIMO (Multiple Input Multiple Output) communication. The present invention relates to a wireless communication system, a wireless transmission device, and a wireless communication method.

  Conventionally, multi-user MIMO technology has been proposed (Patent Document 1, Patent Document 2, and Patent Document 3). Multi-user MIMO has a large number of antenna elements on the base station (or access point) side and a relatively small number of antenna elements on the terminal side, so that a virtual MIMO channel can be formed simultaneously between the base station and a plurality of terminals. To do.

  In other words, the multi-user MIMO transmission technology is such that, on the transmitting station side, independent signals different from each other at the same frequency and the same timing are transmitted from a plurality of transmission antennas to a plurality of communication partner devices, and the entire reception antennas of the plurality of communication partner devices are huge. This is a technique for improving the downlink throughput as a receiving array.

  FIG. 14 is a conceptual diagram showing the configuration of such a multiuser MIMO communication system.

As shown in FIG. 14, the base station BS transmits transmission signals x _{1 to} x _M from antennas _{1 to M} , respectively. Terminals UE _{1 to} UE _k are each provided with two antennas, for example. Terminal UE ₁ receives transmission signals x _{1 to} x _M from the base station via its two antennas and receives signals y ₁ and y ₂ , respectively. Similarly, other terminals UE ₂ ~UE _k, by each of the two antennas, receives a transmission signal x ₁ ~x _M from the base station, the signal y ₃ and _{y 4, ..., y M-} 1 and to receive y _M.

  That is, the example of FIG. 14 illustrates a case where (the number of transmission antennas of the base station) = (the number of reception antennas on one terminal side) × (the number of terminals).

At this time, a received signal vector Y in which the received signals y _{1 to} y _M at the antennas at the receiving side terminals UE _{1 to} UE _k are collected is expressed by the following expression.

ここで、行列Ｈの各要素は、送信側の各アンテナから受信側の各アンテナへの伝送路のインパルス応答に相当し、行列Ｈは「チャネル応答マトリックス」（または「伝送路行列」）と呼ばれる。ベクトルｘは、送信機側での各アンテナへの送信信号を並べたベクトルである。また、ベクトルＮは、受信側の各アンテナで受信される信号に含まれるノイズ成分を並べたものである。

Here, each element of the matrix H corresponds to an impulse response of a transmission path from each antenna on the transmission side to each antenna on the reception side, and the matrix H is called a “channel response matrix” (or “transmission path matrix”). . A vector x is a vector in which transmission signals to each antenna on the transmitter side are arranged. The vector N is an array of noise components included in signals received by the receiving antennas.

  As a transmission beam forming (BF: Beam Forming) method in a conventional multi-user MIMO downlink, a ZF (Zero Forcing) method for forming nulls for all receiving antennas of all terminals other than the own terminal, Various beam forming methods based on the MMSE (Maximum Mean Square Error) method have been devised. The beam forming method based on the MMSE method does not form nulls for all receiving antennas of all terminals other than its own terminal, but allows a certain amount of leakage.

  Here, in the case of a single carrier, a method of estimating a “weighting coefficient” (beam forming weight matrix) for combining transmission signals to be given to each antenna by the MMSE method is disclosed in Japanese Patent Application Laid-Open No. 2007-110664. No.).

  Furthermore, as described in Patent Document 3, another example of a transmission beamforming method in the MIMO downlink is a BD (Block Diagonalization) method.

  Non-Patent Document 1 discloses a BD-VP (Vector Perturbation with Block Diagonalization) method, which is a further improvement of the BD method.

  Hereinafter, according to the disclosure of Non-Patent Document 1, first, a BD method applied to multi-user MIMO (hereinafter referred to as MU-MIMO) will be briefly described.

  That is, in the BD method, as described below, the channel response matrix is combined with a precoding matrix (a matrix for transmission beamforming that expresses a weighting coefficient, hereinafter referred to as “beamforming weight matrix”). (Referred to as a “precoding matrix”).

In the MU-MIMO system, a downlink is assumed. Assume that there are n _T transmission antennas, and n _R reception antennas are provided for each user (each terminal) for n _U users. It is assumed that n _T = n _R × n _U holds.

  At this time, it is assumed that the channel response matrix H is expressed as follows.

ここで、チャネル応答マトリックスの部分行列Ｈiは、ｉ番目のユーザについて、送信側のｎ_T本の送信アンテナと受信側のｎ_R本の受信アンテナとの間の伝送路の応答を示す。また、記号右肩の添え字Ｔは、転置行列を示す。

Here, the partial matrix Hi of the channel response matrix indicates the response of the transmission path between the n _T transmitting antennas on the transmitting side and the n _R receiving antennas on the receiving side for the i-th user. The subscript T on the right side of the symbol indicates a transposed matrix.

  According to the block diagonalization algorithm (BD algorithm) described below, it is possible to cancel interference between users.

  That is, the BD algorithm converts MU-MIMO into a single user MIMO (hereinafter referred to as SU-MIMO) channel. In order to reduce the complexity of processing at the receiver on the user side, equivalent processing for the channel is executed on the transmission side by precoding processing.

  The purpose of the BD algorithm is to find a matrix B represented by the following equation (2).

ここで、０_nRとは、ｎ_R×ｎ_Rのゼロマトリックスであり、Ｈ_eff,i＝Ｈ_iＢ_iとは、ユーザｉについての有効チャネル応答マトリックスである。

Here, 0 _nR is an n _R × n _R zero matrix, and H _{eff, i} = H _i B _i is an effective channel response matrix for user i.

  Further, by subtracting the partial channel response matrix of the user i from the channel response matrix of the entire system of Expression (1), a matrix represented by the following Expression (3) is defined.

式（３）のマトリックスの特異値分解は、以下の式（４）のように表現される。

The singular value decomposition of the matrix of Expression (3) is expressed as the following Expression (4).

そこで、ユーザｉに対するチャネル応答マトリックスＨ_iに対して、上記式（４）中のヌル空間ウェイト行列を乗算して得られる行列について、以下の式（５）で示されるように特異値分解を実行すると、プリコーディング行列Ｂiも以下の式（６）のように表現される。

Therefore, singular value decomposition is performed on the matrix obtained by multiplying the channel response matrix H _i for user i by the null space weight matrix in equation (4) as shown in equation (5) below. Then, the precoding matrix Bi is also expressed as the following equation (6).

特許文献３には、さらに、このようなＢＤアルゴリズムを用いて、マルチユーザＭＩＭＯ送信技術を、マルチキャリアの伝送技術である直交周波数分割多重 （ＯＦＤＭ：Orthogonal Frequency Division Multiplexing）変調方式に適用した例について開示がある。

Patent Document 3 further describes an example in which a multi-user MIMO transmission technique is applied to an orthogonal frequency division multiplexing (OFDM) modulation scheme, which is a multi-carrier transmission technique, using such a BD algorithm. There is disclosure.

  FIG. 15 is a diagram for explaining the configuration of the wireless transmission device 9 that performs transmission beamforming using such a BD algorithm. With reference to FIG. 15, the configuration of such a transmission device 9 will be briefly described below.

  FIG. 15 is a configuration example using a BD directivity control method in the prior art that transmits data to be optimal for the propagation environment and improves the transmission rate by spatial multiplexing.

  The number of antenna elements of the communication device 9 is Mt, the number of communication partner devices is Ma, the number of reception antenna elements of the i-th communication partner device is Mr (i), and transmitted to the i-th communication partner device at the same time and frequency band. An example of a method of determining a communication partner apparatus with L (i) as the number of communication sequences to be performed, Mf as the number of subcarriers, and Mt ≧ Mr (i) is shown.

  The communication device 9 includes a data output circuit 901, a transmission signal conversion circuit 902, IFFT circuits 903-1 to 903-Mt, radio units 904-1 to 904-Mt, antenna elements 905-1 to 905-Mt, and a communication partner designation circuit. 906, a channel information acquisition circuit 907, and a transmission coding determination circuit 908.

  The antenna elements 905-1 to 905-Mt and the radio units 904-1 to 904-Mt perform transmission and reception of radio signals. The channel information acquisition circuit 907 estimates channel information of a plurality of frequencies between each antenna element 905-1 to 905-Mt and each antenna element of the communication partner apparatus. The channel information acquisition method is, for example, performing FFT on information obtained when receiving a known signal obtained via the antenna elements 905-1 to 905-Mt and converting the information into frequency domain information. There is a method for estimating channel information for each frequency band. There is also a method for acquiring channel information from information included in feedback information included in a received signal.

  When the communication partner specifying circuit 906 determines a plurality of communication partner devices with which to communicate, the communication partner specifying circuit 906 transmits the channel information of all frequency bands of the communication partner device through the channel information acquisition circuit 907. Output to. The transmission coding determination circuit 908 performs scheduling to divide communication partner devices into groups that perform simultaneous transmission using the input channel information, and determines the transmission weight and communication quality of each signal sequence for each combination of communication partner devices. The transmission mode including the number of communication streams, the modulation scheme corresponding to the communication stream, and the coding rate is determined. The transmission coding determination circuit 908 outputs the determined transmission mode to the data output circuit 901 and the transmission signal conversion circuit 902.

  The data output circuit 901 generates data to be transmitted to the communication partner apparatus, and outputs the generated data to the transmission signal conversion circuit 902. The transmission signal conversion circuit 902 performs serial-parallel conversion, input of a known signal, encoding for error detection and error correction, and outputs the input data to the IFFT circuits 903-1 to 903-Mt. IFFT circuits 903-1 to 903 -Mt convert the input transmission information in the frequency domain into transmission information for the time domain, and output the transmission information to radio units 904-1 to 904 -Mt. The radio units 904-1 to 904-Mt transmit the input time domain data as radio signals through the antennas 905-1 to 905-Mt.

  Since application of the BD algorithm to such OFDM modulation is essentially the same as in the case of the single carrier described above, description thereof will not be repeated here.

  Further, Non-Patent Document 1 discloses the above-described BD-VP method as nonlinear weighting processing for transmission beamforming.

  In brief, the BD-VP method disclosed in Non-Patent Document 1 converts a MU-MIMO channel into a parallel SU-MIMO channel without interference between users and performs nonlinear precoding by the BD method. This is a technique for reducing transmission power by a VP (Vector Perturbation) algorithm. Furthermore, it is possible to suppress the calculation load by appropriately designing the algorithm of the VP method.

  In a non-linear precoding method such as the VP method, a precoding process is performed on a transmission signal addressed to a receiving device that receives interference between receiving devices, and an interference component is thinned out in advance. However, since the signal after the precoding process has a component due to the propagation path, the transmission power may exceed the specified value.

  Therefore, modulo arithmetic processing is performed on the signal before the precoding processing. “Modulo calculation processing” is to perform a remainder calculation of a predetermined value for the real part and the imaginary part of the input signal. This is equivalent to adding a perturbation signal having a value that is an integral multiple of a specified value to the real part and imaginary part of the input signal. A signal whose transmission power is suppressed within a specified value by modulo calculation is transmitted by beam forming.

  On the other hand, in the reception processing, the modulo arithmetic processing is performed again on the reception signal in which the above-described perturbation signal is added to the desired signal (information signal including data), the perturbation signal component is removed, and the information signal is It is taken out.

  Such a “non-linear precoding method” is also disclosed in Patent Document 4, for example.

JP 2005-328312 A JP 2007-110664 A JP 2009-177616 A JP 2010-154320 A

Manar Mohaisen, Bing Hui, KyungHi Chang, Seunghwan Ji, and Jinsoup Joung, “Fixed-complexity vector perturbation with block diagonalization for MU-MIMO systems,” Proc. 2009 IEEE MICC, pp.238-243,15-17, Dec. 2009

  In the calculation of a precoding matrix for realizing MU-MIMO according to the method as described above, various methods for suppressing the amount of calculation have been proposed.

  However, in general, a dedicated software calculation module, dedicated calculation hardware, or the like is used to calculate such a precoding matrix.

  However, due to various factors such as the following, the precoding matrix calculation process may result in a state deviating from the ideal state, and if such a state occurs, Until the calculation process of the precoding matrix is broken and the calculation process returns to normal, there may be a case where a failure occurs in the transmission process for all users of MU-MIMO.

i) Hardware failure For example, when a failure occurs in some antennas on the transmitter side or some antennas on the receiver side, the channel corresponding to the antenna in which such a failure occurs is received. Since the estimation information (channel state information) about the transmission path from the machine side is not a normal value, the precoding matrix calculation process cannot be executed without failure.

ii) Design or test At the MU-MIMO design stage or test stage, tests are performed only on some terminals, or some hardware failures occur due to trial test conditions, etc. This occurs more frequently than during actual operation. Even in such a case, a state equivalent to the hardware failure of i) can be obtained. In such a case, regarding the essential processing part (arithmetic algorithm) for executing the “precoding matrix calculation process”, the precoding matrix calculation process will not be disrupted without any modification. A configuration that can be used is desirable.

  Hereinafter, a part of such a transmitting side or a receiving side (a part of a plurality of antennas of one transmitter or one receiver and an antenna of a part of receivers of a plurality of receivers) ) Means that communication is not possible, it is called the “Broken antennas effect”, and a transmission line that cannot communicate due to such a “failed antenna effect”. It will be referred to as an “impossible transmission line”.

  Therefore, it is an object of the present invention to prevent the calculation processing of the precoding matrix calculation algorithm for the transmission path in the normal state from being broken even when a transmission path in the disabled state occurs in multi-user MIMO communication. A wireless communication system, a wireless transmission device, and a wireless communication method capable of realizing MIMO communication are provided.

  Another object of the present invention is that, even in the case of an incapable transmission path in multi-user MIMO communication, the precoding matrix calculation process is disrupted without any algorithm correction or hardware adjustment. A wireless communication system, a wireless transmission device, and a wireless communication method that can be prevented.

  According to an aspect of the present invention, there is provided a wireless communication system that performs wireless communication by MIMO (Multiple Input Multiple Output) between a base station and a plurality of terminals. The base station includes a plurality of first antennas, Based on channel state information corresponding to the channel response matrix of the transmission path estimated at the terminal, and for wireless transmission by MIMO from a plurality of first antennas to a plurality of terminals A weighting processing unit for generating a plurality of transmission signals by multiplying the modulated transmission symbol sequence by a weighting coefficient and combining the weighted coefficients, and a first processing unit for transmitting the outputs of the weighting processing units from the plurality of first antennas. 1 based on channel state information received from one transmission processing unit and a plurality of terminals. , A disabled antenna detection unit that detects a transmission path in a communication disabled state among the channels between the base station and the terminal, and a transmission path in the disabled state in the channel state information according to the detection result of the disabled antenna detection unit A channel information repair processing unit that repairs the elements of the channel response matrix corresponding to, and gives them to the control unit, and each of the plurality of terminals includes a plurality of second antennas and a corresponding transmission among the plurality of transmission signals. Based on the reception processing unit for receiving the signal and the reception signal received by the reception processing unit, the channel response matrix of the corresponding transmission path is estimated, and transmitted from the second antenna to the base station as channel state information A second transmission processing unit.

  Preferably, the channel information repair processing unit, based on the channel response matrix for the base station and the plurality of terminals obtained by integrating the channel state information received from the terminal, of the channel response matrix corresponding to the transmission path in the disabled state Of the row or column elements, the non-diagonal component is set to 0, and the diagonal component is set to a predetermined value, whereby the channel response matrix is repaired.

  Preferably, the disabled antenna detection unit adds the size of column or row elements in a channel response matrix for a base station and a plurality of terminals obtained by integrating channel state information received from a terminal. In response to the corresponding value being equal to or less than the predetermined value, the transmission path in the disabled state is detected.

  According to another aspect of the present invention, there is provided a radio transmission apparatus that performs radio communication with a plurality of terminals by MIMO (Multiple Input Multiple Output), wherein a plurality of antennas and channel response matrices of transmission paths estimated by the plurality of terminals are obtained. Based on the corresponding channel state information, a control unit for calculating a weighting coefficient and a transmission coefficient sequence that is modulated by a weighted coefficient for multiplication by wireless transmission from multiple antennas to multiple terminals by MIMO Based on channel state information received from a plurality of terminals, a weighting processing unit for generating a plurality of transmission signals, a transmission processing unit for transmitting the outputs of the weighting processing units from a plurality of antennas, and In the wireless communication by, communication is impossible in the channel between the base station and the terminal According to the detection result of the impossible antenna detection unit that detects a certain transmission path and the impossible antenna detection unit, the channel response matrix element corresponding to the antenna in the disabled state is restored in the channel state information, and the control unit And a channel information repair processing unit for providing.

  Preferably, the channel information repair processing unit, based on the channel response matrix for the base station and the plurality of terminals obtained by integrating the channel state information received from the terminal, of the channel response matrix corresponding to the transmission path in the disabled state Of the row or column elements, the non-diagonal component is set to 0, and the diagonal component is set to a predetermined value, whereby the channel response matrix is repaired.

  Preferably, the disabled antenna detection unit adds the size of column or row elements in a channel response matrix for a base station and a plurality of terminals obtained by integrating channel state information received from a terminal. In response to the corresponding value being equal to or less than the predetermined value, the transmission path in the disabled state is detected.

  According to still another aspect of the present invention, there is provided a wireless communication method for performing wireless communication by MIMO (Multiple Input Multiple Output) between a base station having a plurality of antennas and a plurality of terminals. A step of receiving a transmission signal from the base station, and a step of each of the plurality of terminals estimating a channel response matrix of a corresponding transmission path based on the received reception signal and transmitting the channel response information to the base station as channel state information And, in the wireless communication by MIMO, based on channel state information received from a plurality of terminals, the base station detects a transmission path in a communication disabled state among channels between the base station and the terminal, and the base station Is the channel state information that repairs the element of the channel response matrix corresponding to the transmission path in the disabled state. A base station calculates a weighting factor for wireless transmission by MIMO from a plurality of antennas to a plurality of terminals based on the restored channel state information; and The symbol sequence is multiplied and combined with a weighting coefficient to generate a plurality of transmission signals, and a plurality of transmission signals are transmitted from a plurality of antennas.

  According to the wireless communication system, the wireless transmission device, and the wireless communication method of the present invention, in the multi-user MIMO communication, even when an impossible transmission path occurs, the precoding matrix calculation algorithm for the transmission path in the normal state It is possible to avoid the breakdown of arithmetic processing.

  In addition, according to the wireless communication system, the wireless transmission device, and the wireless communication method of the present invention, in the multiuser MIMO communication, transmission in the disabled state without changing the dedicated processing part for the precoding matrix calculation process Even when a path is generated, it is possible to avoid breaking the precoding matrix calculation process.

3 is a block diagram illustrating a configuration of a wireless transmission device 1000 in the wireless communication system according to the first embodiment. FIG. 3 is a block diagram showing a configuration of terminal apparatus 1100 in the wireless communication system according to Embodiment 1. FIG. In a normal state MIMO communication system, it is a conceptual diagram which shows the relationship between the channel response matrix and the channel state information fed back. It is a conceptual diagram which shows the channel state information fed back when there exists a failed antenna in the receiver side. It is a conceptual diagram which shows the channel state information fed back when there exists a failed antenna in a transmitter. It is a conceptual diagram which shows the channel state information fed back when there exists a failed antenna in a transmitter and a receiver. 6 is a first conceptual diagram for explaining channel information restoration processing executed in radio transmission apparatus 1000 of Embodiment 1. FIG. FIG. 10 is a second conceptual diagram for explaining channel information restoration processing executed in radio transmitting apparatus 1000 according to the first embodiment. FIG. 10 is a third conceptual diagram for explaining channel information restoration processing executed in radio transmitting apparatus 1000 of the first embodiment. FIG. 11 is a diagram illustrating a simulation result of precoding matrix calculation processing in the wireless transmission device 1000. FIG. 10 is a block diagram showing a configuration of a wireless transmission device 2000 in the wireless communication system of the second embodiment. FIG. 11 is a block diagram showing a configuration of terminal apparatus 2100 in the wireless communication system according to the second embodiment. 10 is a flowchart for explaining the operation of radio transmission apparatus 2000. It is a conceptual diagram which shows the structure of a multiuser MIMO communication system. It is a figure for demonstrating the structure of the radio | wireless transmission apparatus 9 which performs transmission beam forming using BD algorithm.

  Hereinafter, a radio communication system according to an embodiment of the present invention will be described with reference to the drawings. In the following embodiments, components and processing steps given the same reference numerals are the same or equivalent, and the description thereof will not be repeated unless necessary.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of radio transmission apparatus 1000 in the radio communication system according to the first embodiment.

  In FIG. 1, for simplicity of explanation, the wireless transmission device 1000 is described as having eight antennas 100-1 to 100-8, but the configuration of the MU-MIMO transmitter is more In general, the number of antennas is not limited to this.

  Referring to FIG. 1, radio transmission apparatus 1000 modulates a serial / parallel conversion unit 20 for serial / parallel conversion of transmission symbols given from input node 10, and each parallel-converted signal using a predetermined modulation scheme. Modulation units 30-1 to 30-8.

  Note that a transmission symbol may include an in-phase component and an orthogonal component, but in FIG. 1, both are represented by one signal line.

  Radio transmitting apparatus 1000 modulates a control unit 50 for calculating a precoding matrix and coefficients in the precoding matrix from control unit 50 based on channel state information (CSI) described later. Weighting processing units 40-1 to 40-8 for multiplying signals from the units 30-1 to 30-8.

  The weighting processing unit 40-1 multiplies the signal from the modulation unit 30-1 by a coefficient in the precoding matrix to generate a signal to be transmitted from each of the antennas 100-1 to 100-8. Devices 42-11 to 42-81. Here, weighting processing units 40-2 to 40-8 that perform weighting processing on signals from other modulation units 30-2 to 30-8 also have the same configuration as the weighting processing unit 40-1.

  When nonlinear precoding as described above is performed as precoding processing, modulo arithmetic processing is performed on the outputs of modulation sections 30-1 to 30-8. Such modulo arithmetic processing is also executed under the control of the control unit 50.

  In addition to such a modulo operation, DPC (Dirty Paper Coding) can be used as an encoding technique for interference cancellation.

  The outputs of the weighting processing units 40-1 to 40-8 are input to the adders 44-1 to 44-8 corresponding to the antennas 100-1 to 100-8, and are combined. For example, the adder 44-1 combines signals for the antenna 100-1 from each of the weighting processing units 40-1 to 40-8. Similarly, the other adders 44-2 to 44-8 also synthesize signals for the corresponding antennas 100-2 to 100-8.

  Further, wireless transmission apparatus 1000 includes up-converters 60-1 to 60-8 for receiving signals from adders 44-1 to 44-8 and converting them into signals to be wirelessly transmitted.

  The up-converter 60-1 receives the output of the adder 44-1, and converts the frequency of the DA converter 64 for digital-to-analog conversion and the signal of the DA converter 64 based on the signal from the local transmitter 70. A frequency conversion unit 66 for amplifying the output of the frequency conversion unit 66 and supplying the amplified signal to the antenna 100-1. The other up-converters 60-2 to 60-8 have the same configuration.

  Radio transmitting apparatus 1000 further includes feedback information receiving unit 80 for receiving channel state information from the receiver side by antennas 100-1 to 100-8, and based on the received channel state information as will be described later. The failure antenna detection unit 82 for detecting the failure antenna (that is, the transmission path in the disabled state), and the channel state information is repaired and given to the control unit 50 according to the detection result of the failure antenna detection unit 82 A channel information repair processing unit 84. Here, “restoration of channel state information” means that, as will be described later, the control unit 50 changes the algorithm of the precoding matrix calculation process even if a transmission path that is disabled occurs. This means that the channel state information is converted to a state that can be executed without any problem.

  In FIG. 1, the portion indicated by a dotted line is not particularly limited, but is, for example, dedicated hardware that operates based on an algorithm for calculating a predetermined precoding matrix, such as a feedback information receiving unit 80, a failure antenna The detection unit 82 and the channel information restoration processing unit 84 may be configured to be retrofitted to such dedicated hardware.

  FIG. 2 is a block diagram showing a configuration of terminal apparatus 1100 in the wireless communication system of the first embodiment.

  Referring to FIG. 2, terminal device 1100 includes antennas 200-1 and 200-2. The wireless communication system includes four terminals corresponding to the exemplary configuration of the wireless transmission device 1000 in FIG. 1, (total number of transmission antennas) = (number of antennas per terminal) × ( The following description will be made assuming that the relationship of the number of terminals) is established.

  Terminal apparatus 1100 includes down-converters 220-1 and 220-2 for down-converting received signals from antennas 200-1 and 200-2. The down converter 220-1 converts the frequency of the output of the low noise amplification unit 232 for amplifying the reception signal from the antenna 200-1 and the low noise amplification unit 222 by the local transmission signal from the local transmission unit 230. A frequency conversion unit 224 for performing the conversion, and an AD conversion unit 226 for performing analog-digital conversion on the output of the frequency conversion unit 224. The down converter 220-2 has the same configuration.

  The terminal device 1100 further includes a weighting processing unit 240 for receiving signals from the down converters 220-1 and 220-2 and executing weighting processing under the control of the control unit 250. The weighting processing unit 240 adds and combines the signals from the multipliers 242-1 and 242-2 for multiplying the weighting coefficients from the control unit 250 and the multipliers 242-1 and 242-2, respectively, and And adder 244 for selectively separating received signals from channels corresponding to apparatus 1100.

  In the terminal device 1100 side as well, when nonlinear precoding as described above is performed as precoding processing on the transmission side, modulo arithmetic processing is performed on the outputs of the down converters 220-1 and 220-2. The Such modulo arithmetic processing is also executed under the control of the control unit 250. In addition to such a modulo operation, when DPC (Dirty Paper Coding) is used as an encoding technique for interference cancellation, a decoding process for this is also executed.

  The output of the weighting processing unit 240 is demodulated by the demodulating unit 270, and then parallel-serial converted by the parallel-serial converting unit 280, and output from the node 290 as a received signal.

  In the calculation processing of the weighting coefficient in the control unit 250, the channel response matrix (transmission path matrix) estimation result for the terminal device 1100 in the channel response estimation unit 260 is used. Note that, for such channel response matrix estimation processing, processing similar to that disclosed in the above-described prior art can be used.

  Further, the channel response matrix for the terminal device 1100 estimated by the channel response estimation unit 260 is fed back from the antennas 200-1 and 200-2 to the radio transmission device 1000 by the channel state information transmission processing unit 262. As sent.

  FIG. 3 is a conceptual diagram showing a relationship between a channel response matrix and channel state information to be fed back in a normal state MIMO communication system.

As illustrated in FIG. 3, the transmission unit transmits transmission signals x _{1 to} x ₈ from eight antennas, and the four terminals UE1 to UE4 respectively receive the signals. Terminal UE1 receives signals y ₁ and y ₂ via two antennas. Similarly, another terminal UE2~UE4 also by the respective two antennas, receiving receives a transmission signal x ₁ ~x ₈ from the base station, the signal y ₃ and y _4, ..., the y ₇ and y ₈ To do.

When the transmission signals x _{1 to} x ₈ are integrated as one vector and the reception signals y _{1 to} y ₈ are also integrated as one vector, they are fed back to the transmitter side based on the channel response matrix estimated on the receiver side. The channel state information CSI is summarized in one matrix as follows, where M = 8.

図４は、受信機側において故障したアンテナがある場合に、フィードバックされるチャネル状態情報を示す概念図である。

FIG. 4 is a conceptual diagram showing channel state information fed back when there is a failed antenna on the receiver side.

  It is assumed that the second antenna of the terminal UE1 (second antenna as a whole terminal) has failed and the second antenna of the terminal UE3 (sixth antenna as a whole terminal) has failed.

  In this case, the matrix of the channel state information CSI fed back to the transmitter indicates that the components of the second and sixth rows are only noise components as shown in FIG. It becomes.

  Here, in the wireless communication system, assuming that the signal-to-noise ratio SNR is high, the norm of the inverse matrix of the matrix of the channel state information CSI is normally transmitted between the transmitting antenna and the receiving antenna. The value is extremely large compared to the case. This means that in the beam forming method such as the MMSE method and the BD-VP method, the absolute value of the weighting factor to the transmission signal becomes an extremely small value, and simply using the fed back channel state information. It means that the MIMO transmission fails.

  FIG. 5 is a conceptual diagram showing channel state information that is fed back when there is a failed antenna in the transmitter.

  In FIG. 5, it is assumed that the second antenna and the eighth antenna of the transmitter are out of order.

  In this case, the matrix of the channel state information CSI fed back to the transmitter indicates that the components in the second column and the eighth column are noise components as shown in FIG. It becomes only.

  Here again, assuming that the signal-to-noise ratio SNR is high in the wireless communication system, the norm of the inverse matrix of the matrix of the channel state information CSI becomes an extremely large value, and the feedbacked channel state information is simply used. And MIMO transmission breaks down.

  FIG. 6 is a conceptual diagram showing channel state information that is fed back when there is a failed antenna in the transmitter and the receiver.

  That is, FIG. 6 shows a case where the antenna failure on the receiver side shown in FIG. 4 and the antenna failure on the transmitter side shown in FIG. 5 occur simultaneously.

  Along with this, the matrix of the channel state information CSI fed back to the transmitter is that the components in the second and sixth rows and the second and eighth columns are accompanied by the failure of these antennas. As shown in FIG. 6, there are only noise components.

  Similarly, assuming that the signal-to-noise ratio SNR is high, MIMO transmission is simply broken if the fed back channel state information is used.

  FIG. 7 is a first conceptual diagram for explaining the channel information restoration processing executed in radio transmitting apparatus 1000 of the first embodiment.

  In FIG. 7, as shown in FIG. 4, it is assumed that the second antenna of the terminal UE1 on the receiver side has failed and the second antenna of the terminal UE3 has failed.

  Therefore, in the matrix of channel state information fed back from the receiver side, the components in the second and sixth rows are only noise components as shown in FIG.

  When the failure antenna detection unit 82 in the wireless transmitter 1000 detects that there is a failed antenna in the matrix of the channel state information to be fed back by the calculation described later, the failure is detected. All the elements in the row of the channel state information matrix are set to zero.

  Next, in the channel information repair processing unit 84, the diagonal element of the row corresponding to the failed antenna in the failed antenna detection unit 82 and having a value set to 0, as will be described later. Is set to a predetermined value a.

  Based on the matrix of the channel state information repaired by the channel information repair processing unit 84 as described above, the control unit 50 calculates a weighting coefficient by a predetermined algorithm for beam forming. In this case, since the diagonal element is not 0, calculation of the precoding matrix for MIMO communication does not break.

  FIG. 8 is a second conceptual diagram for explaining the channel information restoration processing executed in radio transmitting apparatus 1000 of the first embodiment.

  In FIG. 8, it is assumed that the second antenna and the eighth antenna on the transmitter side are out of order as shown in FIG.

  Therefore, in the matrix of channel state information fed back from the receiver side, the components in the second column and the eighth column are only noise components as shown in FIG.

  When the failure antenna detection unit 82 in the wireless transmitter 1000 detects that there is a failed antenna in the column of the matrix of the channel state information to be fed back by the calculation described later, the failure is detected. All the elements of the column of the channel state information matrix are set to zero.

  Next, in the channel information repair processing unit 84, the diagonal element, as will be described later, of the elements in the column corresponding to the failed antenna in the failed antenna detection unit 82 and having a value set to 0. Is set to a predetermined value a.

  Based on the matrix of the channel state information repaired by the channel information repair processing unit 84 as described above, the control unit 50 calculates a weighting coefficient by a predetermined algorithm for beam forming. Also in this case, calculation of the precoding matrix for MIMO communication does not break.

  FIG. 9 is a third conceptual diagram for explaining the channel information restoration processing executed in radio transmitting apparatus 1000 of the first embodiment.

  9, it is assumed that the antenna failure on the receiver side shown in FIG. 4 and the antenna failure on the transmitter side shown in FIG. 5 occur simultaneously as shown in FIG.

  Therefore, in the matrix of channel state information fed back from the receiver side, the components in the second and sixth rows and the second and eighth columns are only noise components as shown in FIG.

  When the failure antenna detection unit 82 in the wireless transmitter 1000 detects that there is a failed antenna in the row or column of the matrix of the channel state information to be fed back by the calculation described later, the failure is detected. Set all the row and column elements of the channel state information matrix to 0.

  Next, in the channel information repair processing unit 84, the failure antenna detection unit 82 will describe the column or row corresponding to the failure antenna and the row or column element whose value is set to 0 will be described later. The diagonal element is set to a predetermined value a.

  Based on the matrix of the channel state information repaired by the channel information repair processing unit 84 as described above, the control unit 50 calculates a weighting coefficient by a predetermined algorithm for beam forming. Also in this case, calculation of the precoding matrix for MIMO communication does not break.

  As described above, in the case of FIG. 9, both the case where a failed antenna is generated on the transmitter side and the case where a failed antenna is generated on the receiver side are included. With reference to FIG. 9, the process of the failure antenna detection unit 82 and the process of the channel information repair processing unit 84 will be described in more detail.

(Faulty antenna detection)
First, a process in which the failure antenna detection unit 82 detects a failure antenna will be described.

The failure antenna detection unit 82 calculates the sum of squares Scol (i) (i = 1, 2,..., M) of the absolute values of the elements in each column of the channel state information matrix H _fb to be fed back as follows. The square sum Srow (j) (j = 1, 2,..., M) of the elements in each row is calculated. Here, such “the sum of squares of the absolute values of the elements of each row (each column) of the matrix of the channel state information” corresponds to the signal power at the time of transmission / reception with the corresponding antenna.

故障アンテナ検知部８２は、Ｓｃｏｌ（ｉ）の値が、所定の値（たとえば、β）よりも小さい列を故障アンテナに対応すると判断し、あるいは、Ｓｒｏｗ（ｊ）の値が、所定の値（たとえば、β）よりも小さい行を故障アンテナに対応すると判断する。

The failure antenna detection unit 82 determines that a column having a value of Scol (i) smaller than a predetermined value (for example, β) corresponds to the failure antenna, or the value of Srow (j) is a predetermined value ( For example, it is determined that a row smaller than β) corresponds to a failed antenna.

(Restore channel state information)
Subsequently, the failure antenna detection unit 82 sets all elements of the matrix H _fb to 0 for the rows and columns determined to correspond to the failure antenna.

Subsequently, the channel information repair processing unit 84 sets the diagonal component of the row or column in which the element is set to 0 among the rows or columns of the matrix H _fb to the value a calculated as follows. To do. Here, as shown in FIG. 9, the total number of antennas on the transmitting side and the receiving side is eight, and in the matrix of channel state information to be fed back, the second row, the sixth row, the second column, The component in the eighth column is exemplified for the case where the failure antenna detection unit 82 sets the value to 0.

That is, the channel information repair processing unit 84 calculates the average sum of squares of the absolute values of elements whose element values are not set to 0 by the failure antenna detection unit 82 among the elements of the rows or columns of the matrix H _fb . By setting the value a, a matrix of repaired channel state information is generated.

  In this case, there are a total of 36 elements whose element values are not set to zero.

無線送信装置１０００の制御部５０は、このようにして修復されたチャネル状態情報の行列に基づいて、所定のビームフォーミングのアルゴリズムに従い、プリコーディング行列を算出する。ここで、制御部５０は、送信アンテナが故障アンテナに相当している場合は、プリコーディング行列の行（プリコーディングの重み）のうち、故障アンテナに相当するものを０ベクトルに設定する。これにより、故障アンテナに相当する送信アンテナへは、送信信号が供給されない。

The control unit 50 of the wireless transmission device 1000 calculates a precoding matrix according to a predetermined beamforming algorithm based on the matrix of the channel state information restored in this way. Here, when the transmission antenna corresponds to the failure antenna, the control unit 50 sets the vector corresponding to the failure antenna among the rows of the precoding matrix (precoding weight) to the 0 vector. As a result, the transmission signal is not supplied to the transmission antenna corresponding to the failed antenna.

  FIG. 10 is a diagram illustrating a simulation result of the precoding matrix calculation process in the wireless transmission device 1000 as described above.

  In FIG. 10, the horizontal axis represents the signal-to-noise ratio (SNR) per user, and the vertical axis represents the bit error rate (BER) simulated under various conditions. Here, the simulated-Shun channel condition is an i.i.d. (independent and identically distributed) MIMO channel in which each path is distributed independently.

  Also in this simulation, it is assumed that the number of antennas on the transmitter side is 8 in total, the number of terminals is 4, and each terminal has two antennas.

Here, let N _T be the number of failure antennas on the transmitter side, and let N _r be the number of failure antennas on the receiver side. Also, a set of numbers of antennas is malfunctioning at the transmitter (index) and S _T, the number of antennas is malfunctioning at the receiver side (index) and S _r.

  The simulation conditions are as follows.

  Note that BD-VP indicates the case where the BD-VP method is used as the beam forming algorithm, and MMSE indicates the case where the MMSE method is used as the beam forming algorithm. All simulations are performed for a single carrier.

1) BD-VP (1): N _T = N _r = 0; S _T = S _r = {φ}
2) BD-VP (2): N _T = 0, N _r = 4; S _T = {φ}, S _r = {2, 3, 5, 7}
3) BD-VP (3): N _T = 2, N _r = 2; S _T = {3, 5}, S _r = {2, 7}
4) BD-VP (4): N _T = 1, N _r = 0; S _T = {1}, S _r = {φ} (no restoration of channel state information)
5) MMSE (1): N _T = N _r = 0; S _T = S _r = {φ}
6) MMSE (2): N _T = 0, N _r = 4; S _T = {φ}, S _r = {2, 3, 5, 7}
7) MMSE (3): N _T = 2, N _r = 2; S _T = {3, 5}, S _r = {2, 7}
8) MMSE (4): N _T = 1, N _r = 0; S _T = {1}, S _r = {φ} (no restoration of channel state information)
The BD in the BD-VP algorithm simulation Shun is a 2BD block (a 4 × 4 matrix in the diagonal direction of the 8 × 8 matrix), and the VP processing is performed for each of such BD blocks. It is supposed to be executed against.

  From FIG. 10, when channel state information is not repaired (BD-VP (4) and MMSE (4)), one transmission antenna fails and signal transmission for MIMO transmission is broken. I understand.

  On the other hand, when channel state information is restored (BD-VP (1) to (3) and MMSE (1) to (3)), MIMO transmission is performed even when a failure antenna exists on the transmission side or reception side. Does not break, indicating that signal separation is taking place.

With the configuration as described above, in the wireless transmission device 1000, due to a hardware failure or a perspective effect, the signal strength of some transmission or reception antennas is remarkably reduced, and the corresponding transmission path becomes incapable of communication. Even in this case, the breakdown of the MIMO transmission is avoided. Further, in order to avoid such a breakdown of the MIMO transmission, in the wireless transmission device 1000, it is not necessary to change the beam forming algorithm itself for signal separation executed by the control unit 50.
(Embodiment 2)
FIG. 11 is a block diagram showing a configuration of radio transmission apparatus 2000 in the radio communication system according to the second embodiment.

  In FIG. 11, it is assumed that a signal to be MIMO transmitted is OFDM-modulated.

It is assumed that there are N subcarriers of the OFDM signal and N _T transmit antennas for NS streams (NS / 2 users). As will be described later, it is assumed that there are two antennas on each receiver side.

  In FIG. 11, differences from the configuration of radio transmitting apparatus 1000 in the case of the single carrier of Embodiment 1 shown in FIG. 1 will be mainly described, and description of common parts will be omitted as appropriate. As described in the description of Patent Document 3 above, the calculation of the precoding matrix for beamforming is essentially the same as in the case of a single carrier even for a multicarrier OFDM signal. is there.

  Referring to FIG. 11, radio transmission apparatus 2000 performs serial / parallel conversion on a transmission symbol provided from input node 10, and parallel conversion with serial / parallel conversion unit 20 for grouping each of N signals. In addition, modulation units 30-1 to 30-NS for modulating each signal with a predetermined modulation method for every N groups are included.

  Note that a transmission symbol may include an in-phase component and an orthogonal component, but both are represented by one signal line in FIG.

  Based on the channel state information, radio transmission apparatus 2000 calculates a control unit 50 for calculating a precoding matrix and coefficients in the precoding matrix from control unit 50 from modulation units 30-1 to 30-8. Weighting processing units 40-1 to 40-N for multiplying signals.

The weighting processing unit 40-1 multiplies the signal from the modulation unit 30-1 by a coefficient in the precoding matrix to generate a signal to be transmitted from each of the antennas 100-1 to 100- _NT. Multipliers 42-11-42-N _T 1 are included. The weighting processing unit 40-1 includes the same configuration as that corresponding to the modulation unit 30-1, corresponding to the modulation units 30-2 to 30-NS. For example, the weighting processing unit 40-1 multiplies the signal from the modulation unit 30-NS by a coefficient in the precoding matrix and transmits the signals from the antennas 100-1 to 100- _NT , respectively. Includes multipliers 42-1NS-42-N _T NS. Furthermore, the weighting processing unit 40-1 integrates signals from the multipliers 42-11 to 42-1NS corresponding to the antenna 100-1 and generates an adder 44-1 that generates a signal for the antenna 100-1. Including. It is compatible with other antennas 100 - 2 to _{100-N T,} similar adder 44-2 (not shown) includes a ~ _{44-N T.} Here, the other weighting processing units 40-2 to 40-N that execute weighting processing on the signals from the modulation units 30-1 to 30-NS also have the same configuration as the weighting processing unit 40-1.

  Note that when nonlinear precoding as described above is performed as the precoding process, a modulo arithmetic process is performed on the outputs of the modulation units 30-1 to 30-NS. Such modulo arithmetic processing is also executed under the control of the control unit 50.

  In addition to such a modulo operation, DPC (Dirty Paper Coding) can be used as an encoding technique for interference cancellation.

Radio transmission apparatus 2000 further includes receiving the weighting processing unit 40-1 to 40-N of the outputs, an up converter 60-1 to _{60-N T} for converting a signal to be wirelessly transmitted.

The up-converter 60-1 receives the output of the weighting processing unit 40-1 and performs an inverse Fourier transform unit 62 for performing an inverse Fourier transform, a DA conversion unit 64 for performing digital-analog conversion, and a signal from the DA conversion unit 64 Includes a frequency conversion unit 66 for frequency conversion based on a signal from the local transmission unit 70, and a power amplification unit 68 for amplifying the output of the frequency conversion unit 66 and supplying it to the antenna 100-1. The other up-converters 60-2 to 60- _NT have the same configuration.

  Other configurations, for example, the configuration of the feedback information receiving unit 80, the failure antenna detection unit 82, the channel information repair processing unit 84, and the like are the same as those of the wireless transmission device 1000 in FIG.

  In FIG. 11, the portion indicated by a dotted line is not particularly limited, but is, for example, dedicated hardware that operates based on a predetermined precoding matrix calculation processing algorithm, such as feedback information receiving unit 80, failure The antenna detection unit 82 and the channel information restoration processing unit 84 may be retrofitted to such dedicated hardware.

  FIG. 12 is a block diagram showing a configuration of terminal apparatus 2100 in the wireless communication system according to the second embodiment.

  In FIG. 12, since the received signal is an OFDM signal, the down converters 220-1 to 220-2 are calculated by the control unit 250 except that a Fourier transform unit 228 is provided. The basic configuration is the same as that of the terminal device 1100 of the first embodiment shown in FIG. 2 except that the weighting factor corresponding to the OFDM transmission is used.

  Also in terminal apparatus 2100, the channel response matrix for terminal apparatus 1100 estimated by channel response estimation section 260 is transmitted from antennas 200-1 and 200-2 to radio transmission apparatus 2000 by channel state information transmission processing section 262. Is transmitted as feedback information.

  FIG. 13 is a flowchart for explaining the operation of radio transmission apparatus 2000.

  Referring to FIG. 13, when the process is started, first, control unit 50 manages period T of the period in which the failure antenna is registered in accordance with the failure antenna state monitoring. The value of the time variable t is incremented (S100).

  Subsequently, the failed antenna detection unit 82 determines whether there is an error in receiving feedback information (channel state information) from the receiving terminal (S102).

  Here, the receiving terminal is set to UE (m) (m = 1, 2, 3, 4). When the signal from the terminal UE (m) is an error, that is, when reception of the channel state information from the receiver side fails, the failed antenna detection unit 82 determines that the state of the failed antenna is present, and the terminal that is in error , The variable UEFBErr (m) for managing the error state is incremented by 1 (S106).

On the other hand, when failure antenna detection unit 82 determines in step S104 that there is no error in receiving channel state information from terminal UE (m), matrix H _{fb of} channel state information received and stored so far. (T, f) is overwritten and updated (S108). Here, f represents a subcarrier in OFDM.

  Furthermore, the failure antenna detector 82 accumulates metrics M (t) for failure antenna detection according to the following equation (S110). Here, the (i, j) component of metrics is as follows.

メトリックスＭ（ｔ）は、したがって、（受信アンテナ本数）×（送信アンテナ本数）の大きさの行列であり、各要素は、時間軸おおよび周波数軸方向におけるパワーの合計に相当する。

The metrics M (t) is therefore a matrix having a size of (the number of reception antennas) × (the number of transmission antennas), and each element corresponds to the total power in the time axis and frequency axis directions.

  Subsequently, when the operation mode is set to “2”, the channel information repair processing unit 84 executes a channel information repair process based on information (failed antenna index) about the detected failed antenna. Then, the control unit 50 calculates a precoding matrix (S122).

  When there is a transmission antenna that is a failed antenna and is not used (S124), the control unit 50 sets a row corresponding to the transmission antenna that is not used in the precoding matrix as a zero vector (S126). As a result, the transmission signal is not supplied to the transmission antenna corresponding to the failed antenna. Subsequently, based on the weighting coefficients from the control unit 50, the weighting processing units 40-1 to 40-N execute transmission signal weighting processing (S130). On the other hand, when there is no unused antenna (S124), the process proceeds to step S130.

On the other hand, if the operation mode is set to “1” in step S112, the control unit 50 calculates a precoding matrix based on the matrix H _fb of the current channel state information (S114), and the control unit Based on the weighting coefficient from 50, the weighting processing units 40-1 to 40-N execute transmission signal weighting processing (S130).

  After the transmission signal weighting process, the transmission signal is transmitted from the antenna (S132).

  Subsequently, the control unit 50 determines whether or not the time variable t is equal to the period T. When the period T has not been reached (S134), the process is returned to step S100.

  On the other hand, when the time variable t has reached the period T (S134), the control unit 50 sets the operation mode to “1” (S136). That is, the mode is set so as not to execute the channel repair process.

  Next, the control unit 50 calculates the average as CheErr (m) for the period T obtained by integrating the variable UEFBErr (m) with respect to the period T, and resets the value of UEFBErr (m) to 0 (S138). ).

  When the failure antenna detection unit 82 determines that the value of CheErr (m) exceeds the predetermined value φ (S140), the failure antenna detection unit 82 sets the operation mode to “2” (restoration of channel state information). (Mode to execute) is notified, and an antenna corresponding to the failure antenna (transmission path in an incapable state) of the antenna of the m-th terminal is added to the failure antenna index (S142).

  Subsequently, the failed antenna detector 82 calculates the time average of the metrics M (t) as Mavg (S144).

  If the failure antenna detection unit 82 determines that the sum of the Mavg element columns is equal to or less than a predetermined value and the transmission antenna is not normally connected (is a failure antenna), the failure antenna detection unit 82 82 notifies the control unit 50 that the operation mode is set to “2” (mode for executing the restoration of the channel state information), and the transmission antenna that is not normally connected (transmission path in the disabled state) Is added to the failed antenna index (S148). In addition, in the detection of the failure antenna on the receiving side and the registration of the failure antenna index, it may be used that the sum of the rows of the Mavg elements is a predetermined value or less.

  Subsequently, the control unit 50 initializes the time variable t and the metrics value to 0 (S150).

  When there is a reception antenna or a transmission antenna detected as a failed antenna for at least a predetermined number of times over the period T by the above processing, channel information repair processing by the channel information repair processing unit 84 Will be executed.

  Note that the detection of the failed antenna is not limited to the method described in FIG. 13, but Scol (i) (i = 1, 2,..., M) or Srow (j) (j = 1, 2, ..., M).

  In the radio communication system according to the second embodiment as described above, even in multicarrier transmission such as OFDM, as in the radio communication system according to the first embodiment, a part of transmission is caused by a hardware failure or a perspective effect. Alternatively, even if the signal strength of the receiving antenna is significantly reduced and the corresponding transmission path becomes incapable of communication, breakdown of the MIMO transmission is avoided. Further, in order to avoid such a breakdown of the MIMO transmission, the radio transmission apparatus 2000 does not need to change the beamforming algorithm itself for signal separation.

  Embodiment disclosed this time is an illustration of the structure for implementing this invention concretely, Comprising: The technical scope of this invention is not restrict | limited. The technical scope of the present invention is shown not by the description of the embodiment but by the scope of the claims, and includes modifications within the wording and equivalent meanings of the scope of the claims. Is intended.

  10 input nodes, 20 serial / parallel conversion units, 30-1 to 30-8 modulation units, 40-1 to 40-8 weighting processing units, 50 control units, 60-1 to 60-8 upconverters, 80 feedback information receiving units , 82 Fault antenna detection unit, 84 channel information repair processing unit, 100-1 to 100-8 antenna, CSI channel state information control unit, 100, 2000 wireless transmission device, 1100, 2100 terminal device.

Claims (7)

A wireless communication system that performs wireless communication by MIMO (Multiple Input Multiple Output) between a base station and a plurality of terminals,
The base station
A plurality of first antennas;
A control unit for calculating a weighting coefficient based on channel state information corresponding to a channel response matrix of a transmission path estimated in the plurality of terminals;
Weighting processing for generating a plurality of transmission signals by multiplying the modulated transmission symbol sequence by the weighting coefficient and combining the modulated transmission symbol sequences for wireless transmission by MIMO from the plurality of first antennas to the plurality of terminals And
A first transmission processing unit for transmitting the output of the weighting processing unit from the plurality of first antennas;
Based on the channel state information received from the plurality of terminals, in wireless communication by MIMO, an impossible antenna detection unit that detects a transmission path in a communication disabled state among channels between the base station and the terminal;
According to the detection result of the disabled antenna detection unit, a channel information repair processing unit that repairs an element of a channel response matrix corresponding to the transmission path in the disabled state in the channel state information, and gives the control unit a channel information repair processing unit With
Each of the plurality of terminals is
A plurality of second antennas;
A reception processing unit for receiving a corresponding transmission signal among the plurality of transmission signals;
Second transmission for estimating the channel response matrix of the corresponding transmission path based on the received signal received by the reception processing unit, and transmitting the channel state information from the second antenna to the base station A wireless communication system comprising a processing unit. The channel information repair processing unit
Based on the channel response matrix for the base station and the plurality of terminals obtained by integrating the channel state information received from the terminal, the row or column of the channel response matrix corresponding to the transmission path in the disabled state The wireless communication system according to claim 1, wherein the channel response matrix is repaired by setting an off-diagonal component to 0 and setting a diagonal component to a predetermined value.   In the channel response matrix for the base station and the plurality of terminals obtained by integrating the channel state information received from the terminal received from the terminal, the disabled antenna detection unit has a column or row element size. The wireless communication system according to claim 1, wherein a transmission path in the disabled state is detected when a value corresponding to the sum of the values is equal to or less than a predetermined value. A wireless transmission apparatus that performs wireless communication with a plurality of terminals by MIMO (Multiple Input Multiple Output),
Multiple antennas,
A control unit for calculating a weighting coefficient based on channel state information corresponding to a channel response matrix of a transmission path estimated in the plurality of terminals;
A weighting processing unit for generating a plurality of transmission signals by multiplying and combining the weighted coefficients to a modulated transmission symbol sequence for wireless transmission by MIMO from the plurality of antennas to the plurality of terminals;
A transmission processing unit for transmitting the output of the weighting processing unit from the plurality of antennas;
Based on the channel state information received from the plurality of terminals, in wireless communication by MIMO, an impossible antenna detection unit that detects a transmission path in a communication disabled state among channels between the base station and the terminal;
According to the detection result of the disabled antenna detection unit, a channel information repair processing unit that repairs an element of a channel response matrix corresponding to the antenna in the disabled state in the channel state information and gives the control unit a channel information repair processing unit A wireless transmission device. The channel information repair processing unit
Based on the channel response matrix for the base station and the plurality of terminals obtained by integrating the channel state information received from the terminal, the row or column of the channel response matrix corresponding to the transmission path in the disabled state The radio transmission apparatus according to claim 4, wherein the channel response matrix is repaired by setting an off-diagonal component to 0 and setting a diagonal component to a predetermined value.   In the channel response matrix for the base station and the plurality of terminals obtained by integrating the channel state information received from the terminal received from the terminal, the disabled antenna detection unit has a column or row element size. The wireless communication system according to claim 4, wherein a transmission path in the disabled state is detected when a value corresponding to the sum of the values is equal to or less than a predetermined value. A wireless communication method for performing wireless communication by MIMO (Multiple Input Multiple Output) between a base station having a plurality of antennas and a plurality of terminals,
Each of the plurality of terminals receiving a transmission signal from the base station;
Each of the plurality of terminals estimates the channel response matrix of the corresponding transmission path based on the received received signal, and transmits the estimated channel response matrix to the base station as channel state information;
The base station detecting, based on the channel state information received from the plurality of terminals, a transmission path in a communication disabled state among channels between the base station and the terminal in wireless communication by MIMO; ,
The base station repairing a channel response matrix element corresponding to the transmission path in the disabled state in the channel state information;
Calculating a weighting factor for the base station to perform radio transmission by MIMO from the plurality of antennas to the plurality of terminals based on the repaired channel state information;
The base station multiplies the modulated transmission symbol sequence by the weighting coefficient and combines them to generate a plurality of transmission signals;
Transmitting the plurality of transmission signals from the plurality of antennas.

Images