JP6441183B2 - Radio relay apparatus and maximum ratio combining reception method - Google Patents

Description

  The present invention relates to maximum ratio combined reception diversity in consideration of residual self-interference power after wraparound cancellation in a full-duplex relay wireless relay apparatus.

  In general, when direct radio communication cannot be performed between a base station and a destination station, a radio relay apparatus (hereinafter referred to as a relay station) is arranged between the base station and the destination station. For example, in the case of FIG. 5, transmission is performed from the base station 902 to the destination station 903 via the relay station 901. In FIG. 5, the relay station 901 uses a full-duplex relay system that retransmits to the destination station 903 with the same radio resources (time and frequency) as the signal received from the base station 902, and improves the frequency utilization efficiency and throughput. (For example, refer to Patent Document 1). In such a full-duplex relay system relay station 901, it is necessary to suppress self-interference in which a signal transmitted from the transmission antenna 802 wraps around the reception antenna 801. For this reason, in the relay station 901, when the demodulation-modulation unit 803 remodulates and transmits the result to the destination station 903, the combining unit 805 generates a cancel signal generated by the sneak cancel unit 804 estimating the sneak path. Processing to subtract.

M. Jain, et al., “Practical, Real-time, Full Duplex Wireless,” Proc., MobiCom 11, 2011. T.K.Y.Lo, “Maximum ratio transmission,” IEEE Trans. On Commun., Vol. 47, No. 10, Oct. 1999.

However, even when the roundabout cancellation is performed appropriately, there is a problem that a residual self-interference component occurs in the signal after the roundabout cancellation due to the estimation error of the roundabout path. In particular, in a full-duplex relay system, the required signal-to-interference plus noise ratio (SINR) for the modulation and coding scheme (MCS) used for communication is If it is not obtained, a demodulation error occurs in the relay station, and communication is not established. For this reason, a full-duplex relay relay station requires a SINR that is greater than the required value for the MCS used for communication. Therefore, as shown in FIG. 6, as one of the techniques for improving SINR at the time of reception, a radio signal transmitted from the transmission station 904 is transmitted to a plurality of reception antennas (701 (1) to 701 (N) of the reception station 905. ), The received signal is multiplied by the weighting coefficients (a ₁ to a _N ) by the multipliers (703 (1) to 703 (N)) of the weighting unit 702, and the maximum ratio is synthesized by the synthesis unit 704 and demodulated. Receive diversity techniques are known. For example, a station using a plurality of simple receiving antennas that do not consider interference components uses a weighting method that considers only signal power because the noise power of each receiving antenna is equal (see, for example, Non-Patent Document 2).

  However, there is a problem that it is difficult to maximize the received SINR when the conventional maximum ratio combining weighting method considering only signal power is applied to the full-duplex relay station.

  In view of the above problems, the radio relay apparatus and the maximum ratio combining reception method according to the present invention maximize the received SINR and reduce the reproduction error rate by performing maximum ratio combining in consideration of residual self-interference components after wraparound cancellation. For the purpose.

The first invention has a plurality of receiving antennas for receiving radio signals transmitted from a base station, demodulates the received signals of the plurality of receiving antennas by maximizing ratio combining, remodulates them from the transmitting antenna at the same frequency, and In the wireless relay device that transmits to the destination station, the response of the wraparound path from the transmission antenna to the reception antenna and the response of the signal path that cancels the wraparound signal from the transmission antenna to the reception antenna are estimated and calculated for each reception antenna A cancellation unit that cancels the cancellation signal from the reception signal for each reception antenna; and a maximum ratio combining unit that combines the reception signals of the plurality of reception antennas by weighting the reception signal for each reception antenna after cancellation by the weighting coefficient. The maximum ratio combining unit includes residual self-interference power for each received signal received from a plurality of receiving antennas. Obtains a weighting coefficient of the maximum ratio combining based on the INR, by weighting the received signal for each receiving antenna synthesized by weighting factors, a number of the plurality of receiving antennas as N (N is a positive integer), the transmission of the base station The response _{GTS of the} circuit, the response H _{S, n} of the path from the base station to the nth (n is an integer from 1 to N) th reception antenna _, and the reception circuit that receives the radio signal from the nth reception antenna response G _R, and _n, the response H _n of the n-th receive antenna coupling loop path, and response G _{T, 0} of a transmission circuit for transmitting a radio signal from the transmitting antenna, the internal wireless relay device to the n-th receive antenna The weighting coefficient an of the _nth receiving antenna is calculated by the following equation using the response GT _{, n} of the cancellation signal path of the cancellation signal path, the attenuation amount √L of the cancellation signal path, and the noise power σ ^2. This The features.

The second invention has a plurality of receiving antennas for receiving radio signals transmitted from the base station, demodulates the received signals of the plurality of receiving antennas by combining them at the maximum ratio, remodulates them from the transmitting antenna at the same frequency. A maximum ratio combining reception method in a radio relay apparatus that transmits to a destination station, and estimates a response of a sneak path from the transmission antenna to the reception antenna and a response of a signal path that cancels a sneak signal from the transmission antenna to the reception antenna The cancel signal calculated for each reception antenna is canceled from the reception signal for each reception antenna, and the reception signals for each reception antenna after cancellation in the cancellation process are weighted by a weighting coefficient to receive signals from a plurality of reception antennas. the running and the maximum ratio combining processing for combining, in a maximum ratio combining process, be received from a plurality of receiving antennas For each received signal, obtains the weighting coefficient of the maximum ratio combining based on the SINR containing residual self-interference power, by weighting the received signal for each receiving antenna synthesized by weighting factors, a number of the plurality of receiving antennas N (N as a positive integer), and the response G _TS of the transmission circuit of the base station, the base station n (n from 1 response H _S route to an integer) -th receive antenna to _n, and _n, n-th A response GR _{, n} of the reception circuit that receives the radio signal from the reception antenna, a response H _n of the wraparound path of the nth reception antenna, a response GT _{, 0} of the transmission circuit that transmits the radio signal from the transmission antenna , Using the response GT _{, n} of the transmission circuit of the cancel signal path to the nth receive antenna inside the radio relay apparatus, the attenuation amount √L of the cancel signal path, and the noise power σ ² , the nth receive antenna of Look with the coefficients a _n and calculates the following equation.

  The radio relay apparatus and the maximum ratio combining reception method according to the present invention can maximize the received SINR and reduce the reproduction error rate by performing maximum ratio combining in consideration of the residual self-interference component after wraparound cancellation.

It is a figure which shows an example of the radio | wireless communications system in this embodiment. It is a figure which shows the basic structural example of a relay station. It is a figure which shows the detailed example of a relay station. It is a figure which shows each parameter. It is a figure which shows a comparative example. It is a figure which shows an example of a reception diversity.

  Hereinafter, embodiments of a wireless relay device and a maximum ratio combining reception method according to the present invention will be described with reference to the drawings. In the present embodiment, the wireless relay device is referred to as a relay station.

  FIG. 1 shows an example of a wireless communication system 100 using a relay station 101 described in the present embodiment. In FIG. 1, a wireless communication system 100 includes a relay station 101, a base station 102, and a destination station 103.

  In FIG. 1, relay station 101 receives a radio signal transmitted from base station 102, demodulates it once, and transmits the modulated radio signal again to destination station 103. Here, the frequency of the radio signal received from the base station 102 and the frequency of the radio signal transmitted to the destination station 103 are the same frequency. As described above, the relay station 101 according to the present embodiment retransmits a radio signal having the same frequency as the radio signal received from the base station 102 to the destination station 103 in real time (same time). There arises a problem that radio waves wrap around the antenna receiving from the base station 102. Therefore, the relay station 101 according to the present embodiment has a function of canceling the sneak signal.

  FIG. 2 shows an overview of the relay station 101 according to the present embodiment. In FIG. 2, the relay station 101 includes an antenna 201 (1), an antenna 201 (2), an antenna 201 (N) (N: a positive integer), an antenna 202, a reception-transmission unit 203, and a wraparound cancellation unit 204 (1). , A wraparound cancel unit 204 (2), a wraparound cancel unit 204 (N), an adder 205 (1), an adder 205 (2), and an adder 205 (N). Here, since the antenna 201 (1), the antenna 201 (2), and the antenna 201 (N) have the same or similar functions, in the following description, the antenna 201 (1), the antenna 201 (2), and the antenna 201 When a description common to (N) is given, the (number) at the end of the code is omitted and the antenna 201 is described. Similarly, the wraparound canceling unit 204 (1), the wraparound canceling unit 204 (2), and the wraparound canceling unit 204 (N) are similar to the wraparound canceling unit 204, omitting (number) at the end of the reference sign when performing a common description. write. In addition, the adder 205 (1), the adder 205 (2), and the adder 205 (N) are also referred to as an adder 205 by omitting (number) at the end of the code when they are described in common.

  In FIG. 2, an antenna 201 is an antenna that receives a radio signal transmitted from the base station 102 shown in FIG.

  The antenna 202 is an antenna that transmits a radio signal to the destination station 103 illustrated in FIG.

  The reception-transmission unit 203 demodulates the signal transmitted from the base station 102 received by the antenna 201, remodulates it, and transmits it from the antenna 202. Here, the reception-transmission unit 203 has the received power of the radio signal transmitted from the base station 102 by combining the signals received by the N antennas from the antenna 201 (1) to the antenna 201 (N) with the maximum ratio. Adjust to maximize.

  Here, the signal received by the antenna 201 includes not only a signal transmitted from the base station 102 but also a signal sneaking around from the antenna 202 on the transmission side, a signal of another wireless device, noise, and the like.

  The wraparound canceling unit 204 generates a signal having a characteristic opposite to the characteristic of the wraparound path in which the radio wave radiated from the antenna 202 is received by the antenna 201. Note that the sneak cancel unit 204 is provided with N sneak cancel units 204 corresponding to each of the N antennas 201 to cancel the signal of the sneak path included in the received signal of the corresponding antenna 201. Generate a cancel signal. For example, the sneak cancel unit 204 (1) generates a cancel signal for canceling the signal of the sneak path included in the reception signal of the antenna 201 (1). Similarly, the sneak cancel unit 204 (N) generates a cancel signal for canceling the signal of the sneak path included in the reception signal of the antenna 201 (N).

  The adder 205 is a circuit that adds the reception signal of each antenna 201 and the cancel signal of the wraparound canceling unit 204 corresponding to each antenna 201. The adder 205 outputs a signal obtained by canceling the sneak signal included in the reception signal of the antenna 201 to the demodulation / modulation unit 203.

  In this way, the relay station 101 can receive the signal from which the signal sneaking from the antenna 202 to the antenna 201 through the sneak path is combined with the maximum ratio, and can retransmit the signal to the destination station 103.

  However, even when the sneak signal is canceled appropriately, there is a problem that a residual self-interference component occurs in the signal after the sneak cancel due to the estimation error of the sneak path. The demodulation error characteristics of the are deteriorated. Therefore, the relay station 101 according to the present embodiment has a function of performing maximum ratio combining in consideration of a residual self-interference component after wraparound cancellation.

  FIG. 3 shows an example of the relay station 101. 3 shows a detailed configuration example of the relay station 101 shown in FIG. 2, and blocks having the same reference numerals as those in FIG. 2 have the same or similar functions as those in FIG.

  In FIG. 3, the relay station 101 includes a path-specific block 351 (1), a path-specific block 351 (2), a path-specific block 351 (N), and a common block 352. Here, the route-specific block 351 (1), the route-specific block 351 (2), and the route-specific block 351 (N) are blocks having the same or similar functions. The (number) at the end is omitted and expressed as a block 351 by route.

  The path-specific block 351 includes a signal synthesizer 301, a received signal converter 302, an analog / digital (AD) converter 303, a cancellation response multiplier 309, a digital / analog (DA) converter 310, and a transmission signal converter 311.

  The signal synthesis unit 301 corresponds to the adder 205 in FIG. 2 and is a circuit that synthesizes the reception signal of the antenna 201 and the cancel signal for canceling the wraparound corresponding to each antenna 201. Then, the signal synthesis unit 301 outputs a reception signal obtained by removing the cancel signal from the reception signal in the analog domain.

  The reception signal conversion unit 302 performs RF (Radio Frequency) signal processing (filtering, amplification, down-conversion, etc.) on the analog reception signal, and converts the reception signal into a baseband signal.

  The AD conversion unit 303 performs analog-to-digital conversion by sampling an analog baseband signal at a predetermined sampling period and converts the analog baseband signal into a digital baseband signal.

  In a common block 352 described later, a signal received by N antennas from the antenna 201 (1) to the antenna 201 (N), and a signal from which a sneak signal corresponding to each antenna 201 is removed is subjected to maximum ratio synthesis and demodulated. , Remodulate and transmit from antenna 202. Further, the common block 352 outputs a remodulated signal to the cancellation response multiplier 309 of the path-specific block 351.

  The cancel response multiplication unit 309 generates a cancel baseband signal by multiplying the transmission signal by a response for canceling the wraparound signal. The method for calculating the cancellation response will be described in detail later.

  The DA conversion unit 310 converts the digital wraparound cancel baseband signal generated by the cancellation response multiplication unit 309 into an analog baseband signal.

  The transmission signal converter 311 performs RF signal processing (up-conversion, filter, amplification, etc.) on the analog baseband signal, and converts it into an RF signal for cancellation. The cancellation RF signal is output to the signal synthesis unit 301. The signal synthesis unit 301 synthesizes a cancellation RF signal with the reception signal, and cancels a sneak signal included in the reception signal.

  Next, the common block 352 will be described. In FIG. 3, the common block 352 includes a maximum ratio combining unit 304, a demodulation-modulation unit 305, a DA conversion unit 306, a transmission signal conversion unit 307, a maximum ratio combination weight calculation unit 308, a control unit 312, and a memory 313.

  Maximum ratio combining section 304 weights each signal received by N antennas from antenna 201 (1) to antenna 201 (N), from which the sneak signal corresponding to each antenna 201 has been removed. Each signal is synthesized later. As a result, the signal from which the wraparound signal is removed can be combined in the maximum ratio so that the reception power of the radio signal transmitted from the base station 102 is maximized. Here, the relay station 101 according to the present embodiment can reduce the residual self-interference component by obtaining a weighting coefficient in consideration of the residual self-interference component due to the wraparound path and weighting the received signal after cancellation.

  The demodulation-modulation unit 305 once demodulates and remodulates the signal received from the base station 102 for regenerative relay. Here, the demodulation / modulation unit 305 also performs a process of calculating a cancellation response for each path-specific block 351 and outputs the calculated cancellation response to the cancellation response multiplier 309 of each path-specific block 351.

  The DA converter 306 converts the digital baseband signal for transmission output from the demodulator-modulator 305 into an analog baseband signal.

  The transmission signal conversion unit 307 performs RF signal processing (up-conversion, filter, amplification, etc.) on the analog baseband signal and converts it to a transmission RF signal.

  The maximum ratio combining weight calculation unit 308 calculates a weighting coefficient for maximum ratio combining in consideration of the residual self-interference component. The weighting coefficient calculation method will be described in detail later.

  The control unit 312 controls the operation of each unit of the relay station 101 based on a program stored in advance inside. For example, the control unit 312 controls the operation sequence of each unit at the start of full-duplex relay, and performs setting and delivery of parameters of each unit. In addition, the control unit 312 stores a response for cancellation, a weight coefficient for maximum ratio synthesis, and the like in the memory 313 for each block 351 for each path. In the example of FIG. 3, the control unit 312 and the memory 313 are provided for easy understanding. However, the functions of the control unit 312 and the memory 313 may be included in each block (for example, the demodulation-modulation unit 305). Good.

  In this way, the relay station 101 according to the present embodiment can cancel the sneak signal from the reception signal of each antenna 201 to each antenna 201 to perform maximum ratio combining and reduce the residual self-interference component. .

Here, in FIG. 3, the AD conversion unit 303, the maximum ratio combining unit 304, the demodulation-modulation unit 305, the DA conversion unit 306, the maximum ratio combination weight calculation unit 308, the cancellation response multiplication unit 309, and the DA conversion unit 310 are It is included in the digital circuit unit 300 that performs digital processing.
[Calculation method of cancellation response]
Next, a method of calculating a cancellation response by which the signal remodulated by the demodulation / modulation unit 305 is multiplied by the cancellation response multiplication unit 309 will be described.

  FIG. 4 shows a correspondence example between each parameter for calculating a cancellation response and each block of the relay station 101. 4 shows the same configuration as that of the relay station 101 described in FIG. 3, but the antenna 201 (n) (n: a positive integer equal to or less than N) is represented by omitting a plurality of path-specific blocks 351. It is drawn as. The cancellation response is calculated by providing a cancellation response calculation unit in the demodulation-modulation unit 305. However, the cancellation response may be provided as an independent block in the common block 352.

Each parameter shown in FIG. 4 is shown below.
H _n : n (the integer from 1 to N) -th response path response
G _{R, n} : Response of the reception circuit (reception signal converter 302) of the nth path-specific block 351
G _{T, n} : Response of the cancel signal path transmission circuit (transmission signal conversion unit 311) of the nth path-specific block 351
G _{T, 0} : Response of the transmission circuit (transmission signal conversion unit 307) in the wraparound path
F _n : Cancel response √L: Attenuation amount of cancel signal path (path from transmission signal converter 311 to signal synthesizer 301) (here, √L uses the same value in N path-specific blocks 351) )
In FIG. 4, the transmission signal of the base station 102 is X, the response of the transmission circuit of the base station 102 is G _TS , the response of the propagation path from the base station 102 to the relay station 101 is H _{S, n} , demodulation - modulation signal of the modulation unit 305 is X _I.

  Here, it is assumed that each of the above parameters is measured or estimated by the demodulation-modulation unit 305 or the like by a known technique. Note that the responses of the transmission circuit and the reception circuit may be measured in advance and stored in the memory 313 or the like.

In FIG. 4, first, the response Y _{0, n} of the cancel signal path from the transmission signal conversion unit 311 to the reception signal conversion unit 302 is estimated by the following equation. Here, W _{0, n} is additional noise (variance σ ² ).

Next, the response Y _{1, n} of the wraparound path (in the air) from the transmission signal conversion unit 307 to the reception signal conversion unit 302 via the antenna 202 and the antenna 201 (n) is estimated by the following equation. Here, W _{1, n} is additive noise (variance σ ² ).

Then, the cancellation response F _n with an analog signal is calculated by the following equation using the equations (1) and (2).

In this way, the relay station 101 obtains the cancellation response F _n used by the cancellation response multiplication unit 309 of the nth path-specific block 351 and cancels the sneak signal of the signal received from the antenna 201 (n). can do. Here, the above-described processing is similarly executed from the first route-specific block 351 to the N-th route-specific block 351.
[Method of calculating the weighting coefficients a _n]
In FIG. 4, the received signal of relay station 101 at the time of execution of wraparound cancellation is expressed by the following equation.

Maximum ratio combining unit 304 weighted by weighting coefficients a _n received signals of the respective sneak path determined by equation (4) for each path by block 351. Then, maximum ratio combining section 304 calculates combined signal ^ X _k by combining the N canceled received signals of relay station 101 as a whole by the following equation.

Further, the weighting factor a _n is expressed by the following equation. Note that [] ^* indicates a complex conjugate.

In the present embodiment, is derived by calculation of the weighting coefficients a _n to the maximum ratio combining SINR (Signal-to-Interference- plus-Noise Ratio). In Expression (6), the left term corresponds to the sum of SINRs of the N path-specific blocks 351, and the right term corresponds to the SINR of the n-th path-specific block 351. That is, the equation (6) can be calculated weighting coefficients a _n of the maximum ratio combining Considering residual self-interference power and noise of the wraparound path.

Next, a description that the weighting coefficients a _n shown in equation (6) is obtained by calculation of SINR. First, the signal S received by the N antennas 201 by receiving signals transmitted from the base station 102 and combined at the maximum ratio can be expressed by the following equation.

Here, in equation (7), the signal power E _S in each path-specific block 351 before multiplication of the weighting factor a _n is calculated by the following equation.

  Further, the interference I is expressed by the following equation.

Here calculated in equation (9), the interference signal in each path-specific block 351 before multiplication of the weighting factor a _n can be expressed by Equation (10), the interference power E _I at that time by the equation (11) Is done. Note that the interference power E _I calculated by the equation (11) corresponds to the residual self-interference power, and the residual self-interference power after wraparound cancellation can be derived analytically.

Noise N _noise is expressed by the following equation. W _{3, n} is the additional noise (variance σ ² ).

Here, in equation (12), the noise power E _noise in each path-specific block 351 before multiplication of the weighting factor a _n is calculated by the following equation.

In this way, the signal power, the residual self-interference power and the noise can be calculated by the equations (8), (11) and (13), respectively, and SINR is (signal) / (interference + noise) = E _S / (E _I + E _noise ) By applying the value determined in this manner to the equation (6) can be derived by calculation of SINR weighting coefficient a _n for the maximum ratio combining.

As described above, the relay station 101 according to this embodiment is determined weighting coefficients maximum ratio residual self-interference power considering the wraparound path combining a _n, a maximum ratio combining the signals received from each antenna 201 Therefore, it is possible to realize full duplex communication relay that maximizes the reception SINR of the relay station 101 and reduces the reproduction error rate.

DESCRIPTION OF SYMBOLS 100 ... Wireless communication system; 101, 101 (1), 101 (2), 101 (N), 901 ... Relay station; 102, 902 ... Base station; 103, 903 ... Destination station; 201, 201 (1), 201 (2), 201 (N) ... antenna; 202 ... antenna; 203 ... reception-transmission unit; 204, 204 (1), 204 (2), 204 ( N) ... wraparound cancel unit; 205, 205 (1), 205 (2), 205 (N) ... adder; 300 ... digital circuit unit; 301, 301 (1), 301 (2) , 301 (N)... Signal synthesizer; 302, 302 (1), 302 (2), 302 (N)... Received signal converter; 303, 303 (1), 303 (2), 303 ( N) ... AD conversion unit; 304 ... maximum ratio combining unit; 305 ... demodulation-modulation unit; 306 ... DA conversion unit; 307 ... transmission signal conversion unit; 308 ... maximum ratio combined weight calculation unit; 309, 309 (1), 309 (2), 309 ( N) ... response multiplier for cancellation; 310, 310 (1), 310 (2), 310 (N) ... DA converter; 311, 311 (1), 311 (2), 311 (N) ... Transmission signal converter; 312 ... Controller; 313 ... Memory; 351, 351 (1), 351 (2), 351 (N) ... Block by path; 352 ... Common block 701 (1), 701 (N), 801... Receiving antenna; 702... Weighting unit; 703 (1), 703 (N). ... Transmission antenna; 803 ... Demodulation-modulation unit; 804 ... times Inclusive canceller; 904 ... transmission station; 905 ... receiving station

Claims (2)

The base station has a plurality of receiving antennas for receiving radio signals transmitted from the base station, demodulates the received signals of the plurality of receiving antennas by combining them with a maximum ratio, remodulates and transmits the signals from the transmitting antenna to the destination station at the same frequency. In the wireless relay device,
A response of a sneak path from the transmission antenna to the reception antenna and a response of a signal path for canceling a sneak signal from the transmission antenna to the reception antenna are estimated, and the cancellation signal calculated for each reception antenna is received by the reception A cancel unit for canceling the received signal for each antenna;
A maximum ratio combining unit that combines the reception signals of the plurality of reception antennas by weighting the reception signals for each of the reception antennas after cancellation by a weighting coefficient;
The maximum ratio combining unit obtains a weighting coefficient for the maximum ratio combining based on SINR including residual self-interference power for each reception signal received from the plurality of receiving antennas, and uses the weighting coefficient to determine the weighting coefficient for each receiving antenna. Received signals are weighted and combined ,
A plurality of said number of receiving antennas as N (N is a positive integer), and the response G _TS of the transmission circuit of the base station, from the base station n (n is an integer from 1 to N) -th receive antenna The response H _{S, n} of the path up to, the response GR _{, n} of the receiving circuit that receives the radio signal from _{the nth} receiving antenna, the response H _{n of the} wraparound path of the _nth receiving antenna , Response GT _{, 0} of the transmission circuit that transmits a radio signal from the transmission antenna , Response GT _{, n} of the transmission circuit of the cancellation signal path to the nth reception antenna inside the radio relay apparatus _, and the cancellation signal path and attenuation √L of, by using the noise power sigma ^2, the weighting factor a _n of n-th of the receiving antenna is calculated by the following equation

A wireless relay device characterized by that. The base station has a plurality of receiving antennas for receiving radio signals transmitted from the base station, demodulates the received signals of the plurality of receiving antennas by combining them with a maximum ratio, remodulates and transmits the signals from the transmitting antenna to the destination station at the same frequency. A maximum ratio combining reception method in a wireless relay device,
A response of a sneak path from the transmission antenna to the reception antenna and a response of a signal path for canceling a sneak signal from the transmission antenna to the reception antenna are estimated, and the cancellation signal calculated for each reception antenna is received by the reception Cancel processing to cancel from the received signal for each antenna,
A maximum ratio combining process for combining the reception signals of the plurality of reception antennas by weighting the reception signals for each of the reception antennas after cancellation in the cancellation process with a weighting coefficient ;
Run
In the maximum ratio combining process, for each received signal received from the plurality of receiving antennas, a weighting coefficient for the maximum ratio combining is obtained based on SINR including residual self-interference power, and the weighting coefficient is used to determine the weighting coefficient for each receiving antenna. Received signals are weighted and combined ,
A plurality of said number of receiving antennas as N (N is a positive integer), and the response G _TS of the transmission circuit of the base station, from the base station n (n is an integer from 1 to N) -th receive antenna The response H _{S, n} of the path up to, the response GR _{, n} of the receiving circuit that receives the radio signal from _{the nth} receiving antenna, the response H _{n of the} wraparound path of the _nth receiving antenna , Response GT _{, 0} of the transmission circuit that transmits a radio signal from the transmission antenna , Response GT _{, n} of the transmission circuit of the cancellation signal path to the nth reception antenna inside the radio relay apparatus _, and the cancellation signal path and attenuation √L of, by using the noise power sigma ^2, the weighting factor a _n of n-th of the receiving antenna is calculated by the following equation

And a maximum ratio combining reception method.

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