JP2011244061A - Radio communication system, transmission device, communication method and transmission method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means such as a radio communication system which is capable of performing MIMO transmission with an excellent transmission characteristic even if a repeating device relays a signal by demodulating the signal.SOLUTION: A communication system comprises a transmitting device, a repeating device and a receiving device. The transmitting device transmits a part of a transmission stream to the repeating device or receiving device. The repeating device receives and demodulates a part of the stream from the transmitting device and transmits to the receiving device after reconfiguring a demodulated radio frame. The receiving device detects the stream transmitted by the transmitting device and all of a stream destined to the receiving device although the stream has been transmitted by the repeating device.

Description

  The present invention relates to a wireless communication system capable of MIMO communication including a transmission device, a relay device, and a reception device.

  In recent years, in the field of wireless communication, as a technique for realizing high-speed transmission, by using a plurality of transmission / reception antennas, a plurality of independent transmission signals are transmitted from a wireless transmission device to a wireless reception device at the same frequency and the same timing. Attention has been focused on MIMO (Multiple Input Multiple Output) transmission that can increase the transmission rate without widening the frequency bandwidth.

  However, in order to obtain good reception characteristics in MIMO transmission, there are many scatterers such as buildings between the transmission device and the reception device, and it is necessary that the spatial correlation is low as in an environment where reception is performed via various paths. . When the spatial correlation is high, it becomes difficult to separate spatially multiplexed MIMO signals, and there is a problem that transmission characteristics are greatly deteriorated.

  In response to such a problem, for example, in Patent Document 1, as shown in FIG. 11, a signal transmitted from a transmission device 5001 having a plurality of antennas is transmitted to a plurality of relay devices 5002-1 to 5002-2. A technique of receiving via a reception device 5003 including a plurality of antennas via the network is disclosed. This realizes a MIMO transmission technique with small spatial correlation by regarding a plurality of relay devices as scatterers.

JP 2003-198442 A

  However, in Patent Document 1 described above, the relay device does not perform MIMO signal separation but merely relays received signals. On the other hand, when a radio frame is reconstructed and relayed after being demodulated or error correction decoded by a relay device like a Decode-and-Forward type relay, it is necessary to perform MIMO separation at the relay device. At this time, when the number of antennas provided in the relay apparatus is smaller than the number of streams spatially multiplexed in the transmission apparatus, or when the spatial correlation between the transmission apparatus and the relay apparatus is high, MIMO separation in the relay apparatus becomes difficult. As a result, there is a problem that transmission characteristics deteriorate.

  In view of the above-described problems, the present invention aims at wireless communication that performs MIMO transmission capable of obtaining good transmission characteristics even when a relay device that relays a signal demodulates and relays the signal. To provide a system and the like.

In view of the above-described problems, the wireless communication system of the present invention is
A wireless communication system capable of MIMO communication including a transmission device, a relay device, and a reception device,
The transmitter is
A transmission unit that transmits a part of the transmission stream to the relay device or the reception device;
The relay device is
A relay receiving unit that receives a part of the stream transmitted by the transmitting device;
A demodulator for demodulating the received stream;
A reconstructing unit for reconstructing a radio frame from the demodulated stream;
A relay transmitter that transmits the reconfigured radio frame to a receiving device;
With
The reception apparatus includes a signal detection unit that receives a stream transmitted from the transmission apparatus and a stream transmitted from the relay apparatus, and performs signal detection on the received stream. .

  In the radio communication system according to the present invention, the transmission device may be configured such that the number of streams transmitted to the relay device is one in the transmission unit.

Moreover, in the wireless communication system of the present invention, the transmission device includes:
A precoding unit that performs precoding so that different streams are transmitted to the relay device or the receiving device;
The transmitting unit transmits different streams to the relay device or the receiving device.

  In the radio communication system according to the present invention, the relay device further includes a MIMO separation unit that performs MIMO separation on the stream received by the relay reception unit.

  In the radio communication system of the present invention, the reconfiguration unit reconfigures a radio frame by assigning the received stream to a time frequency resource different from the time frequency resource at the time of reception.

  In the wireless communication system of the present invention, the reconfiguration unit reconfigures a radio frame by allocating received streams to different time frequency resources.

  In the radio communication system of the present invention, the reconfiguration unit is characterized in that at least two of the reconfiguration units allocate a received stream to the same time frequency resource to reconfigure a radio frame.

  In the wireless communication system of the present invention, the receiving device performs MIMO separation with a smaller number of streams than the number of streams transmitted to the receiving device by the transmitting device.

  The transmission device of the present invention is a transmission device that transmits to at least one relay device and a reception device, and uses the report information obtained from the relay device and the reception device to transmit different streams to the relay device and the relay device. A precoding unit that performs precoding to be transmitted to each receiving apparatus is provided.

  In the transmitting apparatus of the present invention, the precoding unit performs precoding so that each of the relay apparatuses and the receiving apparatus do not interfere with each other.

  In the transmission apparatus of the present invention, the precoding unit performs precoding using linear weights.

  In the transmission apparatus according to the present invention, the precoding unit performs precoding to remove inter-stream interference in advance.

  Moreover, the transmission apparatus of the present invention includes a stream selection unit that selects the number of streams to be transmitted to each of the relay apparatuses and the reception apparatus based on the report information.

The communication method of the present invention is a communication method using a transmission device, a relay device, and a reception device,
The transmission device transmits a part of the transmission stream to a plurality of relay devices or reception devices,
The relay device demodulates at least a received signal and reconfigures and transmits a radio frame,
The receiving apparatus detects all streams transmitted from the transmitting apparatus to the receiving apparatus.

The transmission method of the present invention is a transmission method for transmitting to at least one relay device and a receiving device,
Using the report information obtained from the relay device and the receiving device,
A precoding process for performing precoding such that different streams are transmitted to each of the relay apparatus and the receiving apparatus is provided.

  According to the present invention, it is possible to improve the demodulation performance in the relay device and improve the transmission characteristics by transmitting to the relay device with a smaller number of streams than the number of streams transmitted by the transmission device.

1 is an overall view of a wireless communication system in a first embodiment. It is a figure for demonstrating the function structure of the transmitter in 1st Embodiment. It is a figure for demonstrating the function structure of the relay apparatus in 1st Embodiment. It is a figure for demonstrating the function structure of the relay apparatus in 1st Embodiment. It is a figure for demonstrating the function structure of the receiver in 1st Embodiment. It is a flowchart for demonstrating the flow of the process in 1st Embodiment. It is a whole figure of the radio | wireless communications system in 2nd Embodiment. It is a figure for demonstrating the function structure of the transmitter in 2nd Embodiment. It is a figure for demonstrating the function structure of the receiver in 2nd Embodiment. It is a flowchart for demonstrating the flow of the process in 2nd Embodiment. 1 is an overall view of a wireless communication system in the prior art.

The best mode for carrying out the present invention will be described below with reference to the drawings.
[1. First Embodiment]
First, the first embodiment will be described.

[1.1 System configuration]
FIG. 1 is a schematic diagram of a wireless communication system in the present embodiment. The wireless communication system includes a transmission apparatus 101, relay apparatuses 102-1 and 102-2, and a reception apparatus 103. Each of the transmission apparatus 101 and the reception apparatus 103 includes a plurality of antennas. Moreover, the relay apparatuses 102-1 to 102-2 have one or more antennas. Unless otherwise specified, a case will be described in which the relay device demodulates and decodes and reconstructs and transmits a radio frame. However, the present embodiment is not limited to this, for example, a signal received by the relay device. Amplification and retransmission are also included.

The transmission apparatus 101 transmits the stream to be transmitted to the relay apparatus 102-1 and the stream to be transmitted to the relay apparatus 102-2 separately. Here, the stream represents an independent signal sequence that is spatially multiplexed by the transmission apparatus. For example, it is assumed that the transmission apparatus 101 transmits independent streams of S = [x1 x2 x3 x4] ^T. Here, T represents transposition of the matrix.

The transmission apparatus 101 of this embodiment performs transmission processing and transmits a different stream for each relay apparatus. For example, four S1 = ^{[x1] T} is the relay device 102-1 of the stream, the relay device 102 - 2 S2 = shall send a [x2 x3 ^{x4] T.}

  The relay apparatuses 102-1 and 102-2 will relay S1 and S2, respectively. At this time, since the relay device 101 receives one stream x1, there is no need for MIMO separation in the relay device, so the number of reception antennas in the relay device 102-1 and between the transmission device 101 and the relay device 102-1 are eliminated. Good reception performance can be obtained regardless of the spatial correlation.

  On the other hand, since relay device 102-2 receives three streams, three streams of MIMO separation are required for demodulation. When the transmission apparatus 101 does not perform transmission processing and transmits S, the relay apparatuses 102-1 and 102-2 relay 4 streams. Since it is easier to separate the three streams than to separate the four streams, the MIMO separation performance of the relay apparatus 102-2 is improved.

[1.2 Configuration of each device]
Next, the configuration of each device included in the wireless communication system will be described with reference to the drawings.

[1.2.1 Transmitter]
First, the configuration of the transmission apparatus 10 will be described with reference to FIG. FIG. 2 is a block diagram showing the configuration of the transmission apparatus 101 of this embodiment. Transmitting apparatus 101 includes coding sections 201-1 to 201-4, modulation sections 202-1 to 202-4, mapping sections 203-1 to 203-4, pilot generation section 204, precoding section 205, IFFT (Inverse Fast Fourier Transform) units 206-1 to 206-4, GI (Guard Interval) insertion units 207-1 to 207-4, and wireless transmission units 208-1 to 208-4 And transmission antennas 209-1 to 209-4.

  In the present embodiment, the number of streams and the number of transmission antennas are both four, but may be different as a matter of course.

  In transmission apparatus 101, transmission bits are encoded by encoding sections 201-1 to 201-4 using error correction codes such as convolutional codes, turbo codes, and LDPC (Low Density Parity Check) codes. The encoded bits are mapped to modulation symbols such as QPSK (Quadrature Phase Shift Keying) and QAM (Quadrature Amplitude Modulation) by the modulation units 202-1 to 202-4.

  The modulation symbols are allocated to resources defined in time and frequency by the allocation units 203-1 to 203-4 together with the pilot signal generated by the pilot generation unit 204. The precoding unit 205 performs precoding based on the report information from the relay device or the reception device so that different streams can be transmitted to each relay device. The signals after precoding are frequency-time converted by IFFT units 206-1 to 206-4, guard intervals are inserted by GI insertion units 207-1 to 207-4, and waveforms are transmitted by radio transmission units 208-1 to 208-4. Shaping, D / A conversion, and conversion to a radio frequency are performed and transmitted from the transmission antennas 209-1 to 209-4.

  Details of the processing of the precoding unit 205 will be described. Here, description will be made assuming that the channel between the transmission device and each relay device is fed back as report information from the relay device. Further, the number of transmission antennas included in the transmission apparatus 101 is four, the number of transmission and reception antennas included in the relay apparatus 102-1 is one, and the number of transmission and reception antennas included in the relay apparatus 102-2 is three. It will be described as a book.

Assuming that the channel between the transmission apparatus 101 and the relay apparatus 102-1 is H ₁ , and the channel between the transmission apparatus 101 and the relay apparatus 102-2 is H ₂ , H ₁ is a 1 × 4 matrix, H _2. Is a 3 × 4 matrix. First, H ₁ and H ₂ are subjected to singular value decomposition (Singular Value Decomposition).

Where U ₁ is a 1 × 1 unitary matrix, D ₁ is a 1 × 4 diagonal matrix with singular values as diagonal elements, V ₁ is a 4 × 4 unitary matrix, and U ₂ is 3 × 3. A unitary matrix of columns, D ₂ represents a 3 × 4 diagonal matrix having singular values as diagonal elements, and V ₂ represents a 4 × 4 unitary matrix. The transmission weights used in precoding are as follows.

However, _{W 1} is the weight for the relay device 102-1, _{W 2} is the weight for the relay device 102-2. The _{v 2, 4} fourth column vector of four-dimensional _{V 2, v 1,2, v 1,3} , v 1,4 second column vector of the four-dimensional _{V 1,} respectively, the 4-dimensional _{V 1} The third column vector, V ₁ , represents a four-dimensional fourth column vector.

When the transmission weight W is used, the equivalent channel between the transmission apparatus 101 and the relay apparatuses 102-1 and 102-2 is block-diagonalized as follows.

H ₁ W ₁ is a 1 × 1 matrix, and H ₂ W ₂ is a 3 × 3 matrix. Assume that S = [S1 S2] is transmitted from the transmission apparatus 101. Note that S1 = [x1] and S2 = [x2 x3 x4]. If the received signals at relay apparatuses 102-1 and 102-2 are Y1 and Y2, respectively, Y1 and Y2 are as follows.

  Accordingly, among the streams transmitted by the transmission apparatus 101, S1 is relayed by the relay apparatus 102-1, and S2 is relayed by the relay apparatus 102-2. Note that eigenmode transmission can also be performed by the transmission apparatus 101 and the relay apparatus 102-1 and the transmission apparatus 101 and the relay apparatus 102-2 after block diagonalization.

[1.2.2 Relay device]
Next, the processing of the relay device will be described. FIG. 3 is a block diagram illustrating a configuration of the relay apparatus 102-1. The relay apparatus 102-1 includes a reception antenna 301, a radio reception unit 302, a GI removal unit 303, an FFT (Fast Fourier Transform) unit 304, a propagation path estimation unit 305, and a report information generation unit 306. , A demodulation unit 307, a decoding unit 308, a reconstruction unit 309, an IFFT unit 310, a GI insertion unit 311, a wireless transmission unit 312, and a transmission antenna 313.

  A reception signal received by the reception antenna 301 is converted from a radio frequency to a baseband or A / D converted by the radio reception unit 302. The GI removal unit 303 removes the guard interval, and the FFT unit 304 performs time frequency conversion. The propagation path estimation unit 305 performs propagation path estimation based on the pilot signal, and transmits the propagation path estimation value to the report information generation unit 306 and the demodulation unit 307.

  The report information generation unit 306 generates report information for the transmission device. The report information includes information indicating a channel with the transmission apparatus, information indicating a weight used in precoding, and the like.

  Demodulation section 307 performs demodulation processing using the signal after the FFT and the propagation path estimation result, and calculates coded bit LLR (Log Likelihood Ratio).

  Then, the decoding unit 308 performs error correction decoding on the calculated coded bit LLR. Also, the reconfiguration unit 309 performs re-encoding, re-modulation, and reallocation from the transmission bits decoded by the decoding unit 308 to re-configure radio frames. The re-encoding, re-modulation, and re-assignment may be the same as or different from the encoding, modulation, and assignment performed by the transmission apparatus 101, respectively.

  When the assignment is changed by the relay apparatus 102-1, control information indicating which resource is assigned may be transmitted from the transmission apparatus 101 or may be added by the relay apparatus 102-1.

  The reconfigured radio frame is subjected to frequency time conversion by the IFFT unit 310, a guard interval (GI) is inserted by the GI insertion unit 311, D / A conversion and conversion to a radio frequency are performed by the radio transmission unit 312, and transmission is performed. It is transmitted from the antenna 313.

  FIG. 4 is a block diagram illustrating a configuration of the relay apparatus 102-2. The relay apparatus 102-2 includes reception antennas 401-1 to 401-3, radio reception units 402-1 to 402-3, GI removal units 403-1 to 403-3, and FFT units 404-1 to 404-. 3, a propagation path estimation unit 405, a report information generation unit 406, a MIMO separation unit 407, decoding units 408-1 to 408-3, a reconstruction unit 409-1 to 409-3, and an IFFT unit 410- 1 to 410-3, GI insertion units 411-1 to 411-3, wireless transmission units 412-1 to 412-3, and transmission antennas 413-1 to 413-3.

  The reception signals received by the reception antennas 401-1 to 401-3 are converted from radio frequency to baseband and A / D converted by the radio reception units 402-1 to 402-3, and the GI removal unit 403- The guard interval (GI) is removed at 1 to 403-3, and the time frequency conversion is performed at the FFT units 404-1 to 404-3.

  The propagation path estimation unit 405 performs propagation path estimation based on the pilot signal, and the estimated transmission path estimation value is input to the report information generation unit 406 and the MIMO separation unit 407. Report information generation section 406 generates report information fed back to transmission apparatus 101 from the estimated channel value.

又は、

を用いてＭＩＭＯ分離を行った後、復調により符号化ビットＬＬＲを算出する。 MIMO demultiplexing section 407 demultiplexes the MIMO signal based on the signal after the FFT and the propagation path estimated value, and generates coded bit LLR. MIMO separation can be performed using techniques such as MMSE (Minimum Mean Square Error) detection, MLD (Maximum Likelihood Detection), and interference canceller. For example, in the MMSE detection, when the channel matrix of the k-th subcarrier that transmitted S2 is H (k), the weight M (k) of the following equation,

Or

After performing MIMO separation using, encoded bit LLR is calculated by demodulation.

Σ _n ² represents noise power, and I represents a unit matrix. In addition, the MLD calculates the coded bit LLR as follows.

However, λ (b _{t, q} ) represents the LLR of the q-th bit b _{t, q} of the t-th transmission stream transmitted to the relay apparatus 102-2. β ₊ is a sequence in which b _{t, q} = 0 (or +1) among the bit sequences that can constitute S (k), and β ₋ is b _{t, q} = 1 in the bit sequence that can constitute S (k). This represents a series of (or -1). R (k) represents the k-th subcarrier signal of the signal received by relay apparatus 102-2, and S (k) represents the k-th subcarrier signal of S2.

  The coded bits LLR obtained by the MIMO separation are subjected to error correction decoding by the decoding units 408-1 to 408-3. The transmission bits obtained as a result of decoding are re-encoded, re-modulated, and re-assigned by the reconstructing units 409-1 to 409-3 to reconstruct the radio frame. The reallocation may be the same as or different from the received resource. Further, the same resource may be used in a plurality of streams, or may be different for each stream.

  Then, frequency time conversion is performed by IFFT sections 410-1 to 410-3, guard intervals (GI) are inserted by GI insertion sections 411-1 to 411-3, and waveform shaping is performed by radio transmission sections 412-1 to 412-3. , D / A conversion and radio frequency conversion are performed and transmitted from the transmission antennas 413-1 to 413-3.

  When the relay apparatus 102-1 and the relay apparatus 102-2 reallocate to the same resource, the relayed S1 and S2 are spatially multiplexed and reach the receiving apparatus 103. At this time, the receiving apparatus separates four streams. On the other hand, when the relay device 102-1 and the relay device 102-2 perform the maximum allocation to different resources, the signals are detected separately for S1 and S2. Whether the relay device 102-1 and the relay device 102-2 are assigned to the same resource or to different resources, reception is possible.

[1.2.3 Receiver]
FIG. 5 is a block diagram showing a configuration of the receiving apparatus 103. The receiving apparatus 103 includes receiving antennas 501-1 to 501-4, radio receiving units 502-1 to 502-4, GI removing units 503-1 to 503-4, FFT units 504-1 to 504-4, A propagation path estimation unit 505, a signal detection unit 506, and decoding units 507-1 to 507-4 are provided.

  The reception signals received by the reception antennas 501-1 to 501-4 are converted from a radio frequency to a baseband and A / D converted by the radio reception units 502-1 to 502-4, and a GI removal unit 503-1. The guard interval (GI) is removed at ˜503-4, and the time frequency conversion is performed at the FFT units 504-1 to 504-4.

  The propagation path estimation unit 505 performs propagation path estimation based on the pilot signal, and the estimated transmission path estimation value is output toward the signal detection unit 506. The signal detection unit 506 calculates the LLR of the encoded bits transmitted from the transmission apparatus 101 from the signals input from the FFT units 504-1 to 504-4. When a signal having the number of streams of 1 is received, demodulation is performed to calculate the encoded bit LLR. When a signal having a plurality of streams is received, the coded bit LLR is calculated by performing MIMO separation. Decoding sections 507-1 to 507-4 perform error correction decoding on the coded bit LLR.

[1.3 Process flow]
FIG. 6 is a flowchart of the transmission process of this embodiment. First, error correction coding is performed on transmission bits in step s601, modulation is performed on the coded bits in step s602, and modulation symbols are allocated to time / frequency resources in step s603.

  In step s604, precoding is performed so that a desired stream is transmitted to a plurality of relay apparatuses. The IFFT is performed on the signal after precoding in step s605, a GI is inserted in step s606, and the signal is transmitted to each relay apparatus in step s607.

  In the present embodiment, the precoding using linear weights has been described in the transmission apparatus. However, the present invention is not limited to this, and non-linear precoding such as THP (Tomlinson-Harashima Precoding) is also applicable. . It is also possible to perform non-linear precoding after performing linear precoding.

  Further, in the present embodiment, the relay apparatus that performs demodulation has been described, but the embodiment to which the present invention is applicable is not limited to this, and a relay apparatus that amplifies a received signal and transmits it again may be used.

  Moreover, although the example applied to OFDM was shown in this embodiment, embodiment which can apply this invention is not restricted to this, It can apply also to other multicarrier transmission and single carrier transmission.

[2. Second Embodiment]
Next, the second embodiment will be described. In the first embodiment, the receiving device receives only the signal from the relay device. However, in this embodiment, the receiving device also receives the signal from the transmitting device in addition to the signal from the relay device.

[2.1 System configuration]
FIG. 7 is a schematic diagram of the wireless communication system in the present embodiment. The wireless communication system according to the present embodiment includes a transmission device 701, relay devices 702-1 and 702-2, and a reception device 703.

  The transmission apparatus 701 transmits desired streams to the relay apparatuses 702-1 and 702-2 and the reception apparatus 703, respectively. The relay apparatuses 702-1 and 702-2 receive the streams transmitted from the transmission apparatus 701 as reception apparatuses. Relay to 703. The reception device 703 performs reception processing on the signals transmitted from the relay devices 702-1 and 702-2 and the transmission device 703.

[2.2 Device configuration]
[2.2.1 Transmitter]
FIG. 8 is a block diagram showing the configuration of the transmission apparatus 701 in the present embodiment. Transmitting apparatus 701 includes coding sections 801-1 to 801-4, modulation sections 802-1 to 802-4, pilot generation section 803, allocation sections 804-1 to 804-4, stream selection section 805, Precoding unit 806, IFFT units 807-1 to 807-4, GI insertion units 808-1 to 808-4, radio transmission units 809-1 to 809-4, and transmission antennas 810-1 to 810-4 And is configured.

  The transmission bits are error-correction coded by coding sections 801-1 to 801-4, the coded bits are modulated by modulation sections 802-1 to 802-4, and the modulation symbols are assigned to allocation sections 804-1 to 804-4. Thus, it is allocated to the time / frequency resource together with the pilot signal generated by the pilot generation unit 803. The stream selection unit 805 selects the number of streams to be transmitted to each relay device or reception device based on the report information obtained from the relay device or reception device. The report information includes, for example, a channel matrix, information indicating the number of receivable streams (for example, the number of MIMO ranks), and the like.

  When the report information is the number of receivable streams, the number of streams equal to or less than the number of reported receivable streams is transmitted to each relay apparatus and reception apparatus. For example, assuming that the transmission device 701 transmits four streams x1, x2, x3, and x4, the numbers of streams that can be received by the relay device 702-1, the relay device 702-2, and the reception device 703 are as follows. Suppose that the data is reported to 1, 2, 3 and the transmission device 701.

  At this time, the transmission apparatus 701 can receive a stream such as one stream for the relay apparatus 702-1, one stream for the relay apparatus 702-2, and two streams for the reception apparatus 703. Select a number of streams less than or equal to the number.

  At this time, the precoding unit 806, for example, S1 = [x1] for the relay device 702-1, S2 = [x2] for the relay device 702-2, and S3 = [x3 x4] for the reception device. Precode to send the stream.

  Further, the total number of streams selected by the stream selection unit 805 may be larger than the number of streams transmitted by the transmission device 701. For example, assume that the stream selection unit 701 selects the number of streams that can be received. At this time, for example, the transmission apparatus 701 has S1 = [x1] for the relay apparatus 702-1, S2 = [x1 x2] for the relay apparatus 702-2, and S3 = [x2 x3 x4 for the reception apparatus 703. ], It is possible to transmit some streams to a plurality of streams.

  When the report information is a channel matrix, the stream selection unit 805 calculates the number of receivable streams from the number of ranks based on the channel capacity and the SINR after MIMO separation, and each relay apparatus And the number of streams to be transmitted to the receiving device.

  The precoding unit 806 performs precoding according to the number of streams selected by the stream selection unit 805 so that a desired number of streams is transmitted to each relay device or reception device. Precoding can be performed, for example, as in the first embodiment. First, as described in the first embodiment, block diagonalization is performed for each relay apparatus and reception apparatus. Thereafter, each relay device may be similarly diagonalized.

  The signal output from the precoding unit 806 is frequency-time converted by the IFFT units 807-1 to 807-4, the guard interval (GI) is inserted by the GI insertion units 808-1 to 808-4, and the radio transmission unit 809- 1 to 809-4, D / A conversion and radio frequency conversion are performed and transmitted from the transmission antennas 810-1 to 810-4.

[2.2.2 Receiver]
FIG. 9 is a block diagram illustrating a configuration of the reception device 703. The reception device 703 includes reception antennas 901-1 to 901-4, radio reception units 902-1 to 902-4, GI removal units 903-1 to 903-4, and FFT units 904-1 to 904-4. , A propagation path estimation unit 905, a report information generation unit 906, a signal detection unit 907, and decoding units 908-1 to 908-4.

  The reception signals received by the reception antennas 901-1 to 901-4 are converted from radio frequency to baseband and A / D conversion by the radio reception units 902-1 to 902-4, and a GI removal unit 903-1. ˜903-4 removes the guard interval (GI), and the FFT units 904-1 to 904-4 perform time frequency conversion.

  The propagation path estimation unit 905 performs propagation path estimation based on the pilot signal, and outputs the estimated propagation path estimation value to the report information generation unit 906 and the signal detection unit 907. The report information generation unit 906 generates report information from the propagation path estimation value. Here, the report information is, for example, information indicating a channel between the transmission device 701 and the reception device 703, information indicating the number of streams that can be received by the reception device 703, and the like.

[2.3 Process flow]
FIG. 10 is a flowchart showing the transmission processing of this embodiment. Step s1001 selects the number of streams to be transmitted to each relay device or receiving device from the report information from the relay device and receiving device. In step s1002, based on the number of streams selected in step s1001, precoding is performed so that a desired stream is transmitted to each relay apparatus or reception apparatus, and transmission is performed in step s1003.

[3. Modified example]
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 of the present invention are also within the scope of the claims. include.

  The program that operates in the transmission device, the reception device, and the relay device 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 according 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 transmission device, the reception device, and the relay device may be individually chipped, 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.

101 Transmitting Device 201-1 to 201-4 Encoding Unit 202-1 to 202-4 Modulation Unit 203-1 to 203-4 Allocation Unit 204 Pilot Generation Unit 205 Precoding Unit 206-1 to 206-4 IFFT Unit 207-1 207-4 GI insertion unit 208-1 to 208-4 radio transmission unit 209-1 to 209-4 transmission antenna 102-1 relay device 301 reception antenna 302 radio reception unit 303 GI removal unit 304 FFT unit 305 propagation path estimation unit 306 Report information generation unit 307 Demodulation unit 308 Decoding unit 309 Reconstruction unit 310 IFFT unit 311 GI insertion unit 312 Radio transmission unit 313 Transmission antenna 102-2 Relay device 401-1 to 401-3 Reception antenna 402-1 to 402-3 Radio receiving units 403-1 to 403-3 GI removing units 404-1 to 403-1 04-3 FFT unit 405 Propagation path estimation unit 406 Report information generation unit 407 MIMO separation unit 408-1 to 408-3 Decoding unit 409-1 to 409-3 Reconfiguration unit 410-1 to 410-3 IFFT unit 411-1 ˜411-3 GI insertion unit 412-1 to 412-3 Radio transmission unit 413-1 to 413-3 Transmission antenna 103 Reception device 501-1 to 501-4 Reception antenna 502-1 to 502-4 Radio reception unit 503 1 to 503-4 GI removal unit 504-1 to 504-4 FFT unit 505 propagation path estimation unit 506 signal detection unit 507-1 to 507-4 decoding unit

Claims (15)

A wireless communication system capable of MIMO communication including a transmission device, a relay device, and a reception device,
The transmitter is
A transmission unit that transmits a part of the transmission stream to the relay device or the reception device;
The relay device is
A relay receiving unit that receives a part of the stream transmitted by the transmitting device;
A demodulator for demodulating the received stream;
A reconstructing unit for reconstructing a radio frame from the demodulated stream;
A relay transmitter that transmits the reconfigured radio frame to a receiving device;
With
The reception apparatus includes a signal detection unit that receives a stream transmitted from the transmission apparatus and a stream transmitted from the relay apparatus, and performs signal detection on the received stream. Wireless communication system.   2. The wireless communication system according to claim 1, wherein the number of streams to be transmitted to the relay device is 1 in the transmission unit. The transmitter is
A precoding unit that performs precoding so that different streams are transmitted to the relay device or the receiving device;
The wireless communication system according to claim 1, wherein the transmission unit transmits different streams to the relay device or the reception device.   4. The wireless communication system according to claim 1, wherein the relay apparatus further includes a MIMO separation unit that performs MIMO separation on the stream received by the relay reception unit. 5.   5. The radio communication system according to claim 1, wherein the reconfiguration unit reconfigures a radio frame by assigning the received stream to a time frequency resource different from the time frequency resource at the time of reception. .   6. The radio communication system according to claim 1, wherein the reconfiguration unit allocates the received stream to different time frequency resources to reconfigure a radio frame.   6. The reconfiguration unit according to claim 1, wherein at least two of the reconfiguration units allocate a received stream to the same time frequency resource to reconfigure a radio frame. 6. Wireless communication system.   The radio communication system according to any one of claims 1 to 7, wherein the receiving apparatus performs MIMO separation with a smaller number of streams than the number of streams transmitted to the receiving apparatus by the transmitting apparatus. A transmitting device that transmits to at least one relay device and a receiving device;
Using the report information obtained from the relay device and the receiving device,
A transmission apparatus comprising: a precoding unit that performs precoding so as to transmit different streams to each of the relay apparatus and the reception apparatus.   The transmission apparatus according to claim 9, wherein the precoding unit performs precoding so that each of the relay apparatuses and the reception apparatus do not interfere with each other.   The transmission apparatus according to claim 9, wherein the precoding unit performs precoding using linear weights.   The transmission apparatus according to claim 10 or 11, wherein the precoding unit performs precoding to remove inter-stream interference in advance.   The transmission apparatus according to claim 9, further comprising: a stream selection unit that selects the number of streams to be transmitted to each of the relay apparatuses and the reception apparatus based on the report information. A communication method using a transmission device, a relay device, and a reception device,
The transmission device transmits a part of the transmission stream to a plurality of relay devices or reception devices,
The relay device demodulates at least a received signal and reconfigures and transmits a radio frame,
The communication method, wherein the receiving device detects all streams transmitted from the transmitting device to the receiving device. A transmission method for transmitting to at least one relay device and a receiving device,
Using the report information obtained from the relay device and the receiving device,
A transmission method comprising: a precoding process for performing precoding such that different streams are transmitted to each of the relay device and the reception device.

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