JP2010103682A - Wireless communication system, base station device, relay station device and wireless communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless communication system or the like capable of efficiently performing communication when a terminal device and another terminal device for performing communication through a relay station device communicate with a base station device by using the same resource in the wireless communication system including the relay station device. <P>SOLUTION: When the base station device 10 transmits a signal to a terminal device 30a, first of all, a signal B (interference signal) to a terminal device 30b is subtracted from a desired signal A and the signal is transmitted. The relay station device 20 receives a relay signal obtained by subtracting the interference signal B from the desired signal A received from the base station device 10, and transmits the relay signal to the terminal device 30a. The terminal device 30a receives the interference signal B from the base station device 10 in addition to the relay signal obtained by subtracting the interference signal B from the desired signal A from the relay station device 20 to thereby efficiently receive the desired signal A. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention includes a base station device, a relay station device that relays a signal transmitted from the base station device, a first terminal device that directly communicates with the base station device, and the base station device via the relay station device. The present invention relates to a wireless communication system including a second terminal device that communicates with a station device.

  In order to solve the tightness of frequency resources accompanying the increase in data traffic in recent years, a new radio frequency is allocated for mobile communication, and a new mobile communication system that uses the allocated frequency band (for example, IMT-Advanced system) is underway.

  For such a new mobile communication system, a higher frequency band than the frequency band allocated to the previous system will be allocated, but higher frequency signals will be attenuated more greatly. , Coverage will be narrower than in previous systems.

  As a means for solving such a problem, there is a method in which a relay station device that relays communication between a base station device and a terminal device is provided in a cell. FIG. 15 shows a conventional wireless communication system 9. As illustrated in FIG. 15, the base station device 1010 communicates with the terminal device 1030, the terminal device 1032 and the terminal device 1034.

  Here, relay station apparatus 1020 is interposed between base station apparatus 1010 and terminal apparatus 1032, and relay station apparatus 1022 is interposed between base station apparatus 1010 and terminal apparatus 1034.

  Here, the relay station device can only amplify and transmit the received signal (Amplify-and-Forward: AF type), or can re-modulate and transmit if there is no error once (Decode- and-Forward (DF type) etc., and the terminal device (terminal device located near the cell edge) far away from the base station device communicates with the base station device via the relay station device, so that these terminal devices The cell coverage can be maintained in the same manner as in the conventional system without degrading the reception characteristics.

  As shown in FIG. 15, when such a relay station apparatus is provided in a cell, from the viewpoint of effective use of resources, for example, downlink transmission from the base station apparatus 1010 to the terminal apparatus 1030, and relay station apparatus 1020 In some cases, downlink transmission from the terminal device 1032 to the terminal device 1032 is performed using the same resource.

  In such a case, since the signal transmitted from the relay station apparatus 1020 to the terminal apparatus 1032 is received as an interference signal in the terminal apparatus 1030, the reception characteristics of the terminal apparatus 1030 are significantly deteriorated.

  As means for solving this problem, a method of performing beamforming at the time of transmission from the relay station apparatus 1020 to the terminal apparatus 1032 is disclosed. FIG. 16 shows an outline of the wireless communication system 9 in this case.

  As shown in FIG. 16, each of the base station device, the relay station device, and the terminal device has a plurality of transmission / reception antennas, the downlink from the base station device to the relay station device, and the base station device to the terminal device, and the terminal device In the uplink from the relay station apparatus to the relay station apparatus, transmission is performed in a normal MIMO (Multi-Input Multi-Output) multiplex mode without performing beamforming.

In the downlink from the relay station apparatus to the terminal apparatus, a method of transmitting in a mode in which beam forming is performed (referred to as an eigenmode) is shown. Thus, for example, when transmission is performed from the relay station apparatus 1020 to the terminal apparatus 1032, by performing beam forming toward the terminal apparatus 1032, interference received by the terminal apparatus 1030 from the relay station apparatus 1020 is significantly suppressed. (For example, refer to Patent Document 1).
JP 2007-67726 A

  However, when transmission from the base station apparatus 1010 to the terminal apparatus 1030 and transmission from the relay station apparatus 1020 to the terminal apparatus 1032 (both are downlink transmissions) using the same resource, the position of the terminal apparatus 1032 Depending on the case, the signal transmitted from the base station apparatus 1010 may be received as interference in the terminal apparatus 1032, and in such a case, the reception characteristics of the terminal apparatus 1032 are significantly degraded.

  The method of Patent Document 1 described above is not a method of actively suppressing interference that the base station apparatus 1010 gives to the terminal apparatus 1032, but it is also conceivable to form a sharper beam in order to improve the reception characteristics in the terminal apparatus 1032. However, there is a problem that many antennas are required for this purpose.

  In view of the above problems, an object of the present invention is that, in a wireless communication system including a relay station device, a terminal device and another terminal device that communicates via the relay station device use the same resource. It is to provide a wireless communication system or the like that can efficiently communicate when performing communication with a base station apparatus.

  In view of the above-described problems, a wireless communication system of the present invention includes a base station device, a relay station device that relays a signal transmitted from the base station device, and a first terminal device that directly communicates with the base station device. A wireless communication system including a second terminal device that relays the relay station device to communicate with the base station device, wherein the base station device is a signal addressed to the first terminal device. And a signal destined to the terminal for generating the signal destined for the second terminal, a relay signal generating unit for generating a relay signal by subtracting or adding the signals destined for the two terminals, and the relay signal generating unit Transmitting the relay signal generated by the relay station apparatus, and transmitting the relay signal to the relay station apparatus, and then transmitting a signal addressed to the first terminal apparatus, and the relay station apparatus Said The relay signal receiving means for receiving the relay signal transmitted from the ground station device and the base station device transmitting the signal addressed to the first terminal device, and the relay signal to the second terminal device And a relay signal transmitting means for transmitting.

  In the wireless communication system of the present invention, the relay signal generation unit generates an interference signal for the second terminal apparatus based on the signal addressed to the first terminal apparatus and propagation path information indicating a propagation path change. The relay signal is generated by subtracting the interference signal from the signal addressed to the second terminal device.

  In the wireless communication system of the present invention, the propagation path information includes information on propagation path fluctuations between the base station apparatus and the relay station apparatus, and between the relay station apparatus and the second terminal apparatus. Information on propagation path fluctuation and information on propagation path fluctuation between the base station apparatus and the second terminal apparatus are included.

  In the radio communication system of the present invention, the relay station device further includes an amplifying unit that amplifies the relay signal received by the relay signal receiving unit with a predetermined amplification factor.

  In the radio communication system of the present invention, the base station device adds the signal addressed to the second terminal device and the signal addressed to the first terminal device with a power difference in the relay signal generation means. Thus, a relay signal is generated, and the relay station apparatus extracts each of the signals added from the relay signal in the relay signal transmission means, and the signal addressed to the first terminal apparatus and the fluctuation of the propagation path The interference signal for the second terminal apparatus is generated based on the propagation path information representing the signal, and the result of subtracting the interference signal from the signal addressed to the second terminal apparatus is sent to the second terminal apparatus as a new relay signal. It is characterized by retransmitting.

  In the radio communication system of the present invention, the propagation path information includes information on propagation path fluctuation between the relay station apparatus and the second terminal apparatus and between the base station apparatus and the second terminal apparatus. It is characterized by the fact that propagation path fluctuation information is included.

  The radio communication system of the present invention is characterized in that, in the base station apparatus or the relay station apparatus, a signal level to be transmitted is adjusted so that a transmission level after subtracting the interference signal is within a certain range. To do.

  The base station apparatus of the present invention includes a relay station apparatus that relays a signal transmitted from the base station apparatus, a first terminal apparatus that directly communicates with the base station apparatus, and the base station apparatus via the relay station apparatus. In a base station device connected to a wireless communication system including a second terminal device that performs communication, a terminal-destined signal generating means for generating a signal addressed to the first terminal device and a signal addressed to the second terminal Relay signal generating means for generating a relay signal by subtracting or adding signals addressed to the two terminals, and transmitting the relay signal generated by the relay signal generating means to the relay station device, Signal transmitting means for transmitting a signal addressed to the first terminal device after transmitting a signal to the relay station device.

  Further, in the base station apparatus of the present invention, the relay signal generation means generates an interference signal for the second terminal apparatus based on the signal addressed to the first terminal apparatus and propagation path information indicating a propagation path change. The relay signal is generated by subtracting the interference signal from the signal addressed to the second terminal device.

  Further, in the base station apparatus of the present invention, the relay signal generating means adds the signal destined for the second terminal apparatus and the signal destined for the first terminal apparatus with a power difference to add the relay signal. It is characterized by generating.

  The relay station apparatus according to the present invention is a wireless communication system including a base station apparatus and a plurality of terminal apparatuses. The relay station apparatus relays the relay signal transmitted from the base station apparatus to the terminal apparatus. In addition, when the signal addressed to the first terminal device that communicates directly with the base station device and the signal addressed to the second terminal device that communicates via the relay station are added, the first terminal A signal destined for the device and a signal destined for the second terminal device are respectively extracted, and an interference signal for the second terminal device based on the signal destined for the first terminal device and the propagation path information representing the fluctuation of the propagation path Is generated, subtracted from the signal addressed to the second terminal device, and relayed to the second terminal device.

  The wireless communication method of the present invention includes a base station device, a relay station device that relays a signal transmitted from the base station device, a first terminal device that directly communicates with the base station device, and the relay station device. A wireless communication method in a wireless communication system including a second terminal device that relays and communicates with the base station device, wherein in the base station device, the signal addressed to the first terminal device and the second terminal addressed Is generated, and a relay signal is generated by subtracting or adding the signals addressed to the two terminals, the relay signal is transmitted to the relay station device, and the relay signal is transmitted to the relay station device. After that, the signal addressed to the first terminal device is transmitted, the relay station device receives the relay signal transmitted from the base station device, and the base station device transmits the signal addressed to the first terminal device. Together with And transmits the relay signal to the second terminal device addressed.

  According to the present invention, a base station device, a relay station device that relays a signal transmitted from the base station device, a first terminal device that communicates directly with the base station device, and a relay station device In a wireless communication system including a second terminal device that communicates with the base station device, the base station device generates a signal addressed to the first terminal device and a signal addressed to the second terminal. Then, an operation for subtracting or adding the two signals is performed to generate a relay signal, which is transmitted to the relay station apparatus. Moreover, after transmitting a relay signal to the relay station apparatus, a signal addressed to the first terminal apparatus is transmitted. And the said relay station apparatus receives the relay signal transmitted from the said base station apparatus, and together with the said base station apparatus transmitting the signal addressed to the said 1st terminal device, the said relay signal is transmitted to the said 2nd terminal Send to the device. At this time, the relay signal transmitted from the relay station device to the second terminal device is an interference signal (supplied by the base station device to the second terminal device from a desired signal originally transmitted to the second terminal device). (The signal addressed to the first terminal device) is subtracted, and this signal and the signal transmitted from the base station device to the first terminal device are combined on the propagation path, thereby the second terminal. The apparatus can receive a signal with reduced interference signals.

  Further, an interference signal for the second terminal apparatus is generated based on the signal addressed to the first terminal apparatus and the propagation path information representing the propagation path change, and the interference signal is subtracted from the signal addressed to the second terminal apparatus. By doing so, a relay signal is generated. As a result, it becomes possible to transmit a relay signal obtained by subtracting in advance the interference signal in consideration of the state of the propagation path in the base station apparatus, and the second terminal apparatus can receive the relay signal with the interference signal reduced. .

  Further, the propagation path information includes propagation path fluctuation information between the base station apparatus and the relay station apparatus, propagation path fluctuation information between the relay station apparatus and the second terminal apparatus, and the base station apparatus and the second terminal. Information on propagation path fluctuations with the device is included. As a result, it is possible to generate an interference signal more suitable for the state of the propagation path and subtract it in advance.

  Also, the relay station apparatus amplifies the received relay signal with a predetermined amplification factor. As a result, the base station apparatus can perform amplification and relay on the signal from which the interference signal has been subtracted in advance, and reduce the interference signal in the second terminal apparatus.

  The base station apparatus adds the signal addressed to the second terminal apparatus and the signal addressed to the first terminal apparatus with a power difference to generate a relay signal, and the relay station apparatus is added from the relay signal. Each of the received signals is extracted, an interference signal for the second terminal device is generated based on the signal addressed to the first terminal device and the propagation path information representing the fluctuation of the propagation path, and the signal addressed to the second terminal apparatus The result of subtracting the relay signal from is retransmitted to the second terminal device as a new relay signal. As a result, a signal obtained by subtracting the interference signal in the second terminal device in advance in the relay station device can be transmitted, and the second terminal device can receive a signal in which the interference signal is further reduced.

  The propagation path information includes information on propagation path fluctuation between the relay station apparatus and the second terminal and information on propagation path fluctuation between the base station apparatus and the second terminal. Therefore, by using the propagation path fluctuation information, it becomes possible to perform communication according to the propagation path situation (environment).

  Further, in the base station device or the relay station device, the signal level to be transmitted is adjusted so that the transmission level after subtracting the interference signal falls within a certain range. Thereby, it is possible to prevent a very large peak from occurring in the transmission signal after subtraction of the interference signal.

  The best embodiment in a wireless communication system when the present invention is applied will be described with reference to the drawings.

  First, an outline of the target wireless communication system 1 will be described. FIG. 1 is a diagram for explaining the entire wireless communication system 1. As shown in FIG. 1, a base station device 10, a relay station device 20, and a terminal device 30 (a terminal device 30a and a terminal device 30b) are arranged in the wireless communication system 1.

  When the desired signal A is transmitted from the base station device 10 to the terminal device 30a, first, the desired signal A is transmitted as a relay signal to the relay station device 20. The relay station apparatus 20 retransmits the received desired signal A toward the terminal apparatus 30a (relay transmission). Moreover, the base station apparatus 10 transmits a desired signal B to the terminal apparatus 30b. When the desired signal B and the desired signal A from the relay station apparatus 20 to the terminal apparatus 30a described above are transmitted by the same resource, the desired signal B transmitted from the base station apparatus 10 is transmitted to the terminal apparatus 30a. Is received as an interference signal.

  This state is shown in FIG. 2 using a frame configuration. However, frames F10 and F11 are frames transmitted by the base station apparatus 10, and a frame F12 is a frame transmitted by the relay station apparatus 20. As shown in FIG. 2, since the frame F11 and the frame F12 are transmitted at the same time, the desired signal B transmitted from the base station apparatus 10 is observed as an interference signal for the terminal apparatus 30a. Therefore, in the radio communication system to which the present invention is applied, when the relay station device 20 transmits a signal directed to the terminal device 30a, the interference signal B is transmitted by subtracting the desired signal A, and the interference signal is suppressed. Control as much as you can.

  2 shows a state in which transmission from the relay station device 20 to the terminal device 30a is performed in the frame immediately after the frame F10. However, the present invention is not limited to this. Good.

[First Embodiment]
First, the first embodiment will be described. FIG. 3 is a diagram schematically illustrating the wireless communication system 1 according to the first embodiment. As shown in FIG. 3, in the present embodiment, in order to suppress interference that the base station apparatus 10 gives to the terminal apparatus 30a, an interference signal that the base station apparatus 10 gives to the terminal apparatus 30a from a desired signal A to the terminal apparatus 30a. The base station device 10 is configured to transmit a signal obtained by subtracting B (desired signal B addressed to the terminal device 30b) in advance to the relay station device 20.

  In this embodiment, the relay station apparatus 20 is an AF type, and the signal received by the relay station apparatus 20 is amplified with a predetermined amplification factor and retransmitted. Here, for example, if the attenuation in the distance between the devices and the propagation path fluctuation are ignored and the amplification factor in the relay station device 20 is 1, the terminal device 30a transmits from the relay station device 20 as shown in FIG. A signal obtained by combining desired signal A−interference signal B) and interference signal B transmitted from base station apparatus 10 is received. Therefore, the interference signal B can be canceled, and the terminal device 30a can receive the desired signal A. In an actual environment, the interference signal may be subtracted in advance in the base station apparatus in consideration of distance attenuation, propagation path fluctuation, and amplification factor in the relay station apparatus.

  Here, the configuration of the base station apparatus 10 in the present embodiment is shown in FIG. The base station apparatus 10 includes an encoding unit 102, a modulation unit 104, a pilot signal insertion unit 106, a buffer unit 108, an interference subtraction unit 110, a D / A (Digital to Analog) conversion unit 112, and a radio unit 114. A transmission antenna unit 116, a propagation path multiplication unit 118, a reception unit 120, an A / D (Analog to Digital) conversion unit 122, a radio unit 124, and a reception antenna unit 126. .

  First, the encoder 102 performs error correction encoding on the input transmission data, and the modulator 104 modulates the encoded data. Then, a pilot signal insertion unit 106 adds a known pilot signal for propagation path estimation to the modulated signal. The signal to which the pilot signal is added is input to the interference subtraction unit 110, where the interference signal is subtracted.

  In the present embodiment, since the interference signal is a signal transmitted as the desired signal B from the base station apparatus 10 to the terminal apparatus 30b at the subsequent transmission timing, in the base station apparatus 10, the interference signal is the same as the desired signal. Need to be encoded and modulated, and the generated interference signal is output to the buffer section 108 and the propagation path multiplication section 118.

  The buffer unit 108 holds this signal until it is transmitted as a desired signal (addressed to the terminal device 30b) at a later transmission timing. However, it is assumed that the base station apparatus 10 grasps in advance a signal to be transmitted at the subsequent transmission timing and can perform coding and modulation on the signal.

  The interference signal subtracted in the interference subtracting unit 110 is obtained by using the downlink propagation path information (the propagation path fluctuation received by the interference signal transmitted from the base station) between the base station apparatus 10 and the terminal apparatus 30a as the base station apparatus 10-. The value obtained by dividing the downlink channel information (the channel fluctuation received by the desired signal) between the relay station device 20 and the terminal device 30a and the signal addressed to the terminal device 30b are multiplied by the channel multiplier 118. Signal.

  However, the propagation path information here refers to not only fluctuations due to fading but also distance attenuation and shadowing, and also an amplification factor in the relay station apparatus. The fluctuation of power due to distance attenuation and shadowing can usually be obtained from a measured value of RSSI (Received Signal Strength Indicator), and the RSSI and information indicating propagation path fluctuation due to fading are separately notified to the base station apparatus. It is good also as a structure.

Further, it is assumed that the amplification factor in the relay station device 20 is grasped in advance by the base station device 10. Here, for example, the propagation path information between the base station apparatus 10 and the relay station apparatus 20 is H ₁ , the propagation path information between the relay station apparatus 20 and the terminal apparatus 30 a is H ₂ , and the base station apparatus 10 to the relay station apparatus. the signal to be transmitted via the 20 to the terminal apparatus 30a _{S 1,} the channel information between base station apparatus 10 of the terminal device 30a _{H 3,} from the base station apparatus 10 a signal addressed to the mobile station 30b and _{S 2} In this case, the output of the interference subtracting unit 110 is as shown in Equation 1.

However, here, it is assumed that the transmission power of the base station apparatus 10 and the transmission power of the relay station apparatus 20 are the same, and their transmission powers are different (normally, the relay station apparatus has a lower transmission than the base station apparatus). In the case of using power), the second term of the following expression is multiplied by a coefficient related to the transmission power difference. Further, the amplification factor in the relay station apparatus 20 is assumed to be included in the H _2.

As mentioned earlier, the S ₂ in equation 1 is a signal to be transmitted to the terminal device 30b addressed in a subsequent frame, performs a subtraction in advance generates this signal in the present embodiment. In order to appropriately perform this subtraction, it is assumed that the base station apparatus 10 in the present embodiment grasps all scheduling information in the cell.

Further, the propagation path information H ₁ is notified from the relay station apparatus 20, and the propagation path information H ₂ and H ₃ are notified from the terminal apparatus (terminal apparatus 30 a), received by the reception antenna unit 126, and transmitted by the radio unit 124. After being converted to a frequency capable of A / D conversion, it is converted into a digital signal by the A / D converter 122 and reproduced by the receiver 120.

  After such subtraction of the interference signal is performed, the transmission signal (desired signal-interference signal) is converted into an analog signal in the D / A conversion unit 112 and converted into a frequency that can be transmitted in the radio unit 114. It is transmitted from the transmission antenna unit 116. The base station apparatus 10 also transmits scheduling information indicating resource allocation in the cell to the relay station apparatus 20 and the terminal apparatus 30.

  With such a configuration of the base station device 10, it is possible to generate a signal obtained by subtracting in advance the signal that causes interference for the terminal device 30 (terminal device 30 a) communicating with the relay station device 20 by the base station device 10. Even when the base station apparatus 10 and the relay station apparatus 20 transmit different signals using the same resource, a desired signal can be transmitted to the terminal apparatus 30 (terminal apparatus 30a).

On the terminal device 30a side that communicates with the relay station device 20, a signal obtained by adding the interference to the signal obtained by subtracting the interference in advance is received as in Equation 2, and as a result, only the desired signal is received. be able to. However, noise is omitted here. Further, as described above, when the transmission power of the base station device 10 and the transmission power of the relay station device 20 are different, it is necessary to multiply the term representing the interference signal by a coefficient related to the transmission power difference.

  Next, the configuration of the relay station apparatus 20 is shown in FIG. As illustrated in FIG. 5, the relay station device 20 includes a reception antenna unit 202, a radio unit 204, an A / D conversion unit 206, a buffer unit 208, a reception unit 210, a propagation path estimation unit 212, and a transmission. Unit 214, D / A conversion unit 216, amplification unit 218, radio unit 220, and transmission antenna unit 222.

  When a signal transmitted from the base station device 10 (for example, a signal addressed to the terminal device 30a from the base station device 10 via the relay station device 20) is received, the relay station device 20 receives the signal at the reception antenna unit 202. The radio unit 204 converts the received signal into a frequency that can be A / D converted, and outputs it to the A / D conversion unit 206. The converted signal is converted into a digital signal by the A / D conversion unit 206.

  Since the relay station device 20 in this embodiment is an AF type relay station, demodulation and the like are not performed, and the received signal addressed to the terminal device 30a is sent to the buffer unit 208 and held until an appropriate transmission timing. In addition, the receiving unit 210 demodulates and decodes control information such as scheduling information transmitted from the base station apparatus 10 and extracts information related to signal transmission timing. This information is output to the buffer unit 208 and an amplification unit 218 described later. The propagation path estimation unit 212 estimates a propagation path between the base station device 10 and the relay station device 20 based on the signal input from the A / D conversion unit 206, and the estimated propagation path information is transmitted to the transmission unit. It is fed back to the base station apparatus 10 through 214 and subsequent blocks.

  The signal sent to the buffer unit 208 (the signal addressed to the terminal device 30a from the base station device 10 via the relay station device 20) is sent to the D / A conversion unit 216 at an appropriate timing based on the transmission timing information. And converted into an analog signal. The amplification unit 218 performs amplification at a predetermined amplification factor. In the present embodiment, transmission timing information is also input to the amplifying unit 218 so that a signal addressed to the terminal device 30a can be amplified at an appropriate timing. The amplified signal is converted into a frequency that can be transmitted by the radio unit 220 and then transmitted from the transmission antenna unit 222.

  Moreover, the structure of the terminal device 30a in this embodiment is shown in FIG. Here, the terminal device 30a and the terminal device 30b have the same configuration. As illustrated in FIG. 6, the terminal device 30a includes a reception antenna unit 302, a radio unit 304, an A / D conversion unit 306, a propagation path compensation unit 308, a propagation path estimation unit 310, a demodulation unit 312, The decoding unit 314, the transmission unit 316, the D / A conversion unit 318, the radio unit 320, and the transmission antenna unit 322 are configured.

  In the terminal device 30 a illustrated in FIG. 6, a signal received by the reception antenna unit 302 is converted into a frequency that can be A / D converted by the radio unit 304, and converted to a digital signal by the A / D conversion unit 306. Here, the digital signal converted by A / D conversion section 306 is output to propagation path compensation section 308 and propagation path estimation section 310. The propagation path estimation unit 310 performs propagation path estimation using a known pilot signal, and the propagation path compensation unit 308 performs propagation path compensation using the propagation path estimation value. Then, the signal after propagation path compensation is sent to the demodulator 312 to be demodulated, and decoded by the decoder 314.

  Further, information on the propagation path estimated by the propagation path estimation unit 310 is also output to the transmission unit 316. The input signal is converted into a signal that can be fed back to the base station apparatus 10 in the transmission unit 316, and returned to the base station apparatus 10 from the transmission antenna unit 322 via the D / A conversion unit 318 and the radio unit 320. Is done. In this terminal device 30a, the propagation path between the base station apparatus 10 and the relay station apparatus 20 is estimated separately and fed back to the base station apparatus 10 as propagation path information. At this time, propagation path estimation with the base station apparatus 10 can be performed by receiving a signal addressed to another terminal apparatus transmitted from the base station apparatus 10 or a notification signal to the entire cell.

  By configuring the base station device 10, the relay station device 20, and the terminal device 30 as described above, the base station device 10 subtracts in advance the interference that the base station device 10 gives to the terminal device 30 (terminal device 30a). Can be transmitted, and the relay station device 20 relays this signal, so that interference given to the terminal device can be suppressed.

  Further, the interference suppression method as in the present embodiment is effective when the terminal device 30a receives interference with a certain amount of power from the base station device 10, and when the interference power is low, the base station device 10 generates an interference signal. There is a case where the reception quality of the terminal device 30a can be maintained without subtraction in advance. Therefore, control is performed to determine whether or not to perform subtraction of the interference signal according to the interference power received by the terminal device 30a from the base station device 10 or the received SINR (Signal to Interference and Noise power Ratio) at the terminal device 13. May be.

  For example, a threshold value of interference power is determined in advance, and the interference signal suppression method in the present embodiment is applied when interference exceeding the threshold value is received, and subtraction of the interference signal is performed when interference below the threshold value is received. The desired signal is transmitted as it is without being performed. By performing such processing, it is possible to appropriately transmit a signal obtained by subtracting interference to a terminal apparatus that is greatly affected by interference.

  Furthermore, in a system using multicarrier transmission, there is a situation in which the influence of interference varies greatly from subcarrier to subcarrier. However, when such a system is targeted, only a subcarrier to which interference exceeding a certain threshold is applied in advance It is good also as a structure which subtracts interference with an apparatus.

  Further, in the present embodiment, only the subtraction of the interference signal that the base station apparatus 10 gives to the terminal apparatus 30a has been described, but apart from this, there is a case where interference (intersymbol interference) occurs due to the influence of the delayed wave in the propagation path In some cases, the received signal power may drop due to propagation path fluctuations. In this embodiment, since the base station apparatus 10 grasps in advance the propagation path fluctuation when the signal reaches the terminal apparatus 30a via the relay station apparatus 20 from the base station apparatus 10, such propagation path It is possible to compensate in advance for characteristic deterioration due to influence.

For example, in Equation 1, when not only S ₂ but also S ₁ is divided and transmitted by H ₁ H ₂ , terminal device 30 receives S ₁ instead of H ₁ H ₂ S ₁ as shown in Equation 2. Can do. Therefore, when the received power drops significantly due to fluctuations in H ₁ H _2, the reception characteristics can be improved by performing processing (transmission equalization) according to the propagation path for the signal originally intended to be transmitted. .

[Second Embodiment]
Next, the second embodiment will be described. In 1st Embodiment, although the base station apparatus 10 transmitted the signal which subtracted the interference which the base station apparatus 10 gives to the terminal device 30a beforehand, and the relay station apparatus 20 relayed the signal, the interference was simply carried out. The signal after interference subtraction may have a very large peak only by subtraction. Therefore, in the present embodiment, an example in which a method for suppressing the peak of a transmission signal is applied to a base station apparatus is shown.

  In the second embodiment, it is assumed that the wireless communication system includes a base station device 12, a relay station device 22, and a terminal device 32 (terminal device 32a and terminal device 32b).

  Here, the base station device 12 is the base station device 10 of the first embodiment in FIG. 3, the relay station device 22 is the relay station device 20 of the first embodiment in FIG. 3, and the terminal device 32a and the terminal device 32b. Corresponds to the terminal devices 30a and 32b of the first embodiment in FIG. 3, and the same components are denoted by the same reference numerals and detailed description thereof is omitted.

Next, a transmission signal peak suppression method that is the subject of this embodiment will be described. The method in the present embodiment is a method called THP (Tomlinson-Harashima Precoding), which can be realized by performing a modulo operation on the signal after subtracting the interference signal. The output M (x) of this modulo calculation is expressed by Equation 3.

  However, x represents an input to the modulo calculation, that is, a signal after the interference signal is subtracted from a signal to be originally transmitted, and [y] represents a maximum integer (floor function) not exceeding y. Further, k is a constant determined only by the modulation scheme of the signal originally desired to be transmitted. When the modulation scheme of the signal originally intended to be transmitted is, for example, QPSK, k is 2√2.

  Here, when x is a complex signal, the modulo operation may be performed separately for the real part and the imaginary part. FIG. 7 shows input / output characteristics of the modulo calculation. As shown in FIG. 7, the output M (x) of the modulo operation is suppressed within a certain range regardless of the value of the input x. Therefore, the peak of the transmission signal can be suppressed by using the modulo operation.

  In a receiver (terminal device) that receives a signal subjected to such processing on the transmission side, it is necessary to estimate a signal that should be received originally (a signal that the transmission side originally wants to transmit) from the received signal. This can be done by using arithmetic.

  Specifically, when the received signal to which interference is added is y, the above M (y) may be calculated, and M (y) is an estimated value of the signal that should be received. This means that an adjustment value for suppressing the peak is added on the transmission side, and the adjustment value added on the transmission side is restored using the same calculation on the reception side.

  Next, FIG. 8 shows the configuration of base station apparatus 12 in the present embodiment that transmits a signal in which a peak is suppressed using such a modulo operation. However, in FIG. 8, blocks having the same functions as those of the base station apparatus 10 of FIG. 4 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 8, the base station apparatus 12 in the present embodiment basically includes a modulo operation unit 140 that performs the modulo operation described above in the base station apparatus 10 shown in the first embodiment, and an interference subtraction unit. 110 is added to the subsequent stage. However, in the present embodiment, the pilot signal is not subjected to interference subtraction or modulo calculation. In order to distinguish the pilot signals transmitted from the base station apparatus 12 and the relay station apparatus 22, the base station Different pilot signals are transmitted from the device 12 and the relay station device 22, respectively.

  As described above, by providing the base station device 12 with the modulo calculation unit 140, it is possible to generate and transmit a signal with a suppressed peak even when transmitting a signal obtained by subtracting interference in advance.

  Next, the configuration of the terminal device 32 (terminal device 32a) in the present embodiment is shown in FIG. However, in FIG. 9, blocks having the same functions as those of the terminal device 30 a in FIG. 6 are denoted by the same reference numerals, and detailed description thereof is omitted. As illustrated in FIG. 9, the terminal device 32 a in the present embodiment has a configuration in which a modulo arithmetic unit 340 that performs modulo arithmetic is added to the subsequent stage of the propagation path compensation unit 308 in addition to the terminal device 30 a illustrated in the first embodiment. ing.

  By performing the modulo operation in the modulo operation unit 340, the adjustment value added in the modulo operation unit 140 of the base station apparatus shown in FIG. 8 can be restored and the modulation signal that should be received can be obtained.

  Moreover, the relay station apparatus 22 in this embodiment is realizable with the same structure as the relay station apparatus 20 of FIG. 5 shown in 1st Embodiment.

  As described above, according to the present embodiment, when the base station apparatus 12 transmits a signal obtained by subtracting in advance the interference that the base station apparatus 12 gives to the terminal apparatus 32a in the subsequent frame, A very large peak is prevented from occurring, and the terminal device 32a can reproduce a signal that should be received from the transmitted signal (which should be originally transmitted to the transmitting side).

  In the above-described embodiment, the modulo is used to subtract the interference signal from the base station device 12 observed in the terminal device 32a communicating with the relay station device 22 and suppress the peak of the signal after the interference subtraction. Although the configuration is such that the calculation is performed, the interference signal from the base station apparatus 12 may be estimated to be smaller than that actually observed and subtracted. A radio communication system in such a case will be described. That is, it is a wireless communication system in which the base station device 14 communicates with the terminal device 34 a via the relay station device 24. FIG. 10 shows the configuration of the base station device 14 included in the wireless communication system in this case.

  As shown in FIG. 10, the base station apparatus 14 in the case of subtracting interference estimated to be smaller than what is actually observed in the terminal apparatus 34a has a configuration in which a coefficient multiplication unit 150 is added to the configuration in FIG. In the coefficient multiplier 150, the interference signal is multiplied by a coefficient greater than 0 and equal to or less than 1.

  For example, this coefficient may be set to a value according to the received SNR. When the received SNR differs for each subcarrier in multicarrier transmission, a different coefficient may be calculated and multiplied for each subcarrier. Good. However, when this coefficient is set to 1, the base station apparatuses in FIG. 10 and FIG. 8 are exactly the same.

  In the modulo calculation, the energy of the desired signal is used to subtract the interference, and the characteristics may be slightly deteriorated. However, by subtracting the interference multiplied by such a coefficient, the terminal device actually performs the subtraction. Although a signal slightly different from the observed interference signal is subtracted, the extra energy of the desired signal is not used, so that good characteristics can be obtained.

  FIG. 11 shows the configuration of the terminal device 34a that receives a signal transmitted from the base station device 14 shown in FIG. As shown in FIG. 11, the terminal device 34a that receives the signal transmitted from the base station device 14 of FIG. 10 has a configuration in which a coefficient multiplier 350 is added to the configuration of FIG. Then, after the base station apparatus 14 multiplies the same coefficient as that multiplied by the interference signal, the modulo operation is performed. With such a configuration, the signal transmitted from the base station apparatus 14 shown in FIG. 10 can be received with good characteristics.

[Third Embodiment]
Next, a third embodiment will be described. In the first embodiment and the second embodiment described above, a method has been described in which the base station device transmits a signal obtained by subtracting in advance the interference given by the base station device to the terminal device that communicates with the relay station device in the subsequent frame. However, it may be configured such that the interference subtraction performed in the base station apparatus in the first and second embodiments is performed in the relay station apparatus. For this purpose, it is necessary to notify the desired signal and the interference signal from the base station device to the relay station device, and in this embodiment, a method of adding and transmitting a difference in transmission power between the desired signal and the interference signal is applied. An example will be shown.

  Specifically, two signals (desired signal and interference signal) with a difference in transmission power are multiplexed from the transmission source and transmitted to the relay station device, and after both signals are demodulated and decoded in the relay station device, Modulate again and subtract the interference signal from the desired signal. However, it is assumed that the relay station device can receive a signal from the transmission source with high reception power. The relay station device first demodulates and decodes the signal set to high transmission power at the transmission source, Is again modulated and subtracted from the received signal to extract a signal set at a low transmission power at the transmission source, and to demodulate and decode it. An outline of the wireless communication system 3 is shown in FIG.

  As shown in FIG. 12, in the wireless communication system 3 in the present embodiment, the base station device 16 transmits the sum of two signals (A, B) with a power difference to the relay station device 26. Here, the signal A is a desired signal addressed to the terminal device 36a, and the signal B is a desired signal addressed to the terminal device 36b (interference signal for the terminal device 36a).

Moreover, a described in FIG. 12 is a coefficient indicating the power allocated to each signal (0 <a <0.5), and the signal A is transmitted from the base station apparatus 16 with high signal power. . Here, the received signal r in the relay station device 26 can be expressed by the following Equation 4.

However, A and B represent modulated signals to be transmitted, respectively, and n represents noise. Further, here, for the sake of simplicity, propagation path fluctuation is not considered. The relay station apparatus 26 that has received a signal represented by Expression 4 first demodulates the signal A transmitted with high power. At this time, the signal B is treated as an interference signal. Thereafter, the demodulated signal is remodulated and the following subtraction is performed.

  When the signal A is remodulated and subtracted in consideration of power distribution in this way, a signal in which noise is added to the signal B is extracted as shown in Equation 5. The relay station device 26 demodulates this signal and obtains a demodulation result for the signal B. By such subtraction processing, the signal B transmitted with lower power can also be demodulated. Then, the relay station device 26 uses the two signals thus obtained to perform interference signal subtraction processing (in the first and second embodiments, the base station device) as shown in the first and second embodiments. The interference signal (signal B) received by the terminal device 36a from the base station device 16 can be suppressed by performing transmission to the terminal device 36a.

  FIG. 13 shows the configuration of the base station apparatus 16 in the present embodiment. As illustrated in FIG. 13, the base station apparatus 16 in the present embodiment includes an encoding unit 160 (160a, 160b), a modulation unit 162 (162a, 162b), a power coefficient multiplication unit 164 (164a, 164b), and an addition Unit 166, buffer unit 168, pilot signal insertion unit 170, D / A conversion unit 172, radio unit 174, and transmission antenna unit 176.

  In this base station apparatus 16, first, error correction encoding of transmission data is performed in the encoding unit. In the present embodiment, data addressed to a terminal device (terminal device 36a) that communicates via the relay station device 26 is encoded in the encoding unit 160a, and a terminal device that directly communicates with the base station device 16 in the encoding unit 160b. Data addressed to (terminal device 36b) is encoded. The output of the encoding unit 160 is sent to the modulation unit 162, and modulation is performed.

  Then, the power coefficient multiplier 164 multiplies each coefficient (a in Equation 4) for adjusting the transmission power, and then adds them. At this time, the power coefficient multiplier 164a multiplies the square root of “1-a”, and the power coefficient multiplier 164b multiplies the square root of “a”. Thereby, the signal addressed to the terminal device 36a communicating via the relay station device 26 has high power, and the signal addressed to the terminal device 36b directly communicating with the base station device 16 (interference signal for the terminal device 36a) has low power. Adjusted to be transmitted.

  Further, the signal addressed to the terminal device 36b is also sent to the buffer unit 168 and held until it is transmitted in the subsequent frame. After these two signals are added in adder 166, a known pilot signal for propagation path estimation is inserted in pilot signal inserter 170, and converted into an analog signal in D / A converter 172. Then, after being converted into a frequency that can be transmitted by the wireless unit 174, the signal is transmitted from the transmission antenna unit 176. With this configuration, a signal addressed to the terminal device 36a communicating via the relay station device 26 and a signal addressed to the terminal device 36b communicating directly with the base station device 16 are multiplexed and transmitted at an appropriate power ratio. Can do.

  Moreover, the structure of the relay station apparatus 26 in this embodiment is shown in FIG. As illustrated in FIG. 14, the relay station device 26 according to the present embodiment includes a reception antenna unit 250, radio units 252 and 288, an A / D conversion unit 254, a propagation channel compensation unit 256, and a propagation channel estimation unit 258. Demodulation units 260, 272, decoding units 262, 274, encoding units 264, 276, modulation units 266, 278, power coefficient multiplication unit 268, subtraction unit 270, propagation path multiplication unit 280, interference A subtracting unit 282, a pilot signal inserting unit 284, a D / A converting unit 286, and a transmitting antenna unit 290 are provided.

  A signal transmitted from the base station device 16 (a signal obtained by multiplexing two signals with a power difference) is received by the receiving antenna unit 250 of the relay station device 26 and can be A / D converted by the radio unit 252. After being converted to a proper frequency, the A / D converter 254 converts the analog signal into a digital signal. After A / D conversion, a pilot signal for propagation path estimation inserted by the base station apparatus 16 is sent to the propagation path estimation unit 258, and a known signal is used between the base station apparatus 16 and the relay station apparatus 26. A propagation path estimation process is executed.

  Further, the data signal is sent to the propagation path compensation unit 256 together with the propagation path estimation value calculated by the propagation path estimation unit 258, and processing for compensating for the propagation path fluctuation is performed. The signal compensated for the fluctuation of the propagation path is demodulated in the demodulator 260, and the data transmitted in the decoder 262 is reproduced.

  In the relay station device 26 according to the present embodiment, this demodulation processing is performed on a signal addressed to the terminal device 36a that communicates via the relay station device 26 (signal transmitted with high transmission power: signal A), and the base station A signal addressed to the terminal device 36b that communicates directly with the station device 16 (signal transmitted with low transmission power: signal B) is treated as interference. The signal reproduced by the above processing (the signal addressed to the terminal device 36a) is encoded and modulated in the encoding unit 264 and the modulation unit 266 in the same manner as those performed in the base station device 16.

  Then, the power coefficient multiplication unit 268 multiplies the same coefficient (square root of “1-a”) as that multiplied by the base station device 16. The output from the power coefficient multiplier 268 is the same signal as the output of the power coefficient multiplier 164 a in FIG. 13 and is sent to the subtractor 270.

  In the subtracting unit 270, a process of subtracting the output of the power coefficient multiplying unit 268 from the signal after propagation path compensation is performed, and in this subtraction process, a terminal device 36b that directly communicates with the base station apparatus 16 as shown in Equation 5 is performed. The addressed signal can be extracted. The signal extracted in this way is demodulated by the demodulator 272, and the data transmitted by the decoder 274 is reproduced.

  Thus, since the reproduced signal addressed to the terminal device 36b becomes an interference signal for the terminal device 36a, the interference signal is subtracted as shown in the first and second embodiments.

The interference signal reproduced by the decoding unit 274 is subjected to the same encoding and modulation as those performed by the base station apparatus 16 by the encoding unit 276 and the modulation unit 278, and is sent to the propagation path multiplying unit 280. The propagation path information notified from the terminal device 36a is also sent to the propagation path multiplication unit 280, and is multiplied with the interference signal for the terminal device 36a. However, the propagation path information reported from the terminal device 36a is a relay station apparatus 26 and the propagation path information of H ₂ between the terminals 36a, the channel information H ₃ between the base station apparatus 16 of the terminal device 36a There, the interference signal to the terminal apparatus 36a (the signal transmitted from the base station apparatus 16 to the terminal device 36b) and S _2, the output of the channel multiplication unit 280 is expressed by the following equation.

The output from the propagation path multiplying unit 280 and the output from the modulating unit 266 are input to the interference subtracting unit 282 to perform subtraction of interference. The output of the modulation unit 266 is a signal set to high transmission power in the base station device 16, and is a desired signal for the terminal device 36a. Therefore, the interference subtracting unit 282 performs a process of subtracting the output of the propagation path multiplying unit 280 from the output of the modulating unit 266. When the output of the modulation unit 266 (desired signal for the terminal device 36a) and S _1, the output of the interference subtraction unit 282 is represented by the following formula.

  The signal from which interference is subtracted in advance by interference subtracting section 282 is sent to pilot signal inserting section 284, and a pilot signal for propagation path estimation is added. This pilot signal may be a known signal between the relay station device 26 and the terminal device. The output of pilot signal insertion section 284 is converted to an analog signal by D / A conversion section 286, converted to a frequency that can be transmitted by radio section 288, and then transmitted from transmission antenna section 290 to terminal device 36a. . With this configuration, the terminal device 36a demodulates and decodes each of the desired signal and the interference signal, and generates a signal obtained by subtracting the interference signal from the desired signal in advance. It can be sent to 36a.

  Further, the terminal device in the present embodiment can be realized with the same configuration as that shown in FIG.

  As described above, in the present embodiment, the configuration in which the interference signal is simply subtracted from the desired signal as in the first embodiment has been described. However, as in the second embodiment, the subsequent stage of the interference subtraction unit 282 of the relay station apparatus. A modulo arithmetic unit may be provided to prevent a peak from occurring in the signal after interference subtraction.

  In the present embodiment, the relay station device 26 does not determine whether or not there is an error in the decoding result. However, an error determination unit may be provided after the decoding unit to detect an error. . If an error occurs in the desired signal, the subsequent processing is not performed, and the relay station device stops transmission of the signal addressed to the terminal device 36a. When an error occurs in the interference signal, the desired signal itself may be transmitted to the terminal device 36a without performing the subtraction of the interference signal, or the interference signal cannot be subtracted from the base station device. Therefore, it may be controlled to stop the transmission of the desired signal.

It is a figure which shows the outline of the radio | wireless communications system in embodiment. It is a figure for demonstrating the frame structure in embodiment. It is a figure which shows the outline of the radio | wireless communications system in 1st Embodiment. It is a figure for demonstrating the structure of the base station apparatus in 1st Embodiment. It is a figure for demonstrating the structure of the relay station apparatus in 1st Embodiment. It is a figure for demonstrating the structure of the terminal device in 1st Embodiment. It is a figure for demonstrating the input-output characteristic of a modulo calculation. It is a figure for demonstrating the structure of the base station apparatus in 2nd Embodiment. It is a figure for demonstrating the structure of the terminal device in 2nd Embodiment. It is a figure for demonstrating the structure of the base station apparatus in 2nd Embodiment. It is a figure for demonstrating the structure of the terminal device in 2nd Embodiment. It is a figure which shows the outline of the radio | wireless communications system in 3rd Embodiment. It is a figure for demonstrating the structure of the base station apparatus in 3rd Embodiment. It is a figure for demonstrating the structure of the relay station apparatus in 3rd Embodiment. It is a figure for demonstrating the outline of the conventional radio | wireless communications system. It is a figure for demonstrating the outline of the conventional radio | wireless communications system.

Explanation of symbols

1, 3 Wireless communication system 10, 12, 14, 16 Base station apparatus 102 Encoding unit 104 Modulating unit 106 Pilot signal inserting unit 108 Buffer unit 110 Interference subtracting unit 112 D / A conversion unit 114 Radio unit 116 Transmitting antenna unit 118 Propagation path Multiplying unit 120 Receiving unit 122 A / D converting unit 124 Radio unit 126 Receiving antenna unit 140 Modulo calculating unit 150 Coefficient multiplying unit 20, 26 Relay station device 202 Receiving antenna unit 204 Radio unit 206 A / D converting unit 208 Buffer unit 210 Receiving Unit 212 propagation path estimation unit 214 transmission unit 216 D / A conversion unit 218 amplification unit 220 radio unit 222 transmission antenna unit 30, 30a, 30b terminal device 302 reception antenna unit 304 radio unit 306 A / D conversion unit 308 propagation path compensation unit 310 Propagation path estimation unit 312 Regulating unit 314 decoding unit 316 transmitting unit 318 D / A converter 320 radio unit 322 transmitting antenna unit 340 Modulo arithmetic unit 350 coefficient multipliers

Claims (12)

A base station apparatus; a relay station apparatus that relays a signal transmitted from the base station apparatus; a first terminal apparatus that directly communicates with the base station apparatus; and the base station apparatus that relays the relay station apparatus; A wireless communication system including a second terminal device that performs communication of
The base station device
A terminal-addressed signal generating means for generating a signal addressed to the first terminal device and a signal addressed to the second terminal;
Relay signal generating means for generating a relay signal by subtracting or adding signals addressed to the two terminals;
A signal transmission means for transmitting the relay signal generated by the relay signal generation means to the relay station apparatus, and transmitting a signal addressed to the first terminal apparatus after transmitting the relay signal to the relay station apparatus;
With
The relay station device
Relay signal receiving means for receiving a relay signal transmitted from the base station device;
In addition to the base station device transmitting a signal addressed to the first terminal device, a relay signal transmitting means for transmitting the relay signal to the second terminal device;
A wireless communication system comprising:   The relay signal generating means generates an interference signal for the second terminal apparatus based on a signal addressed to the first terminal apparatus and propagation path information representing a propagation path change, and a signal addressed to the second terminal apparatus The wireless communication system according to claim 1, wherein a relay signal is generated by subtracting the interference signal from the base station.   The propagation path information includes propagation path fluctuation information between the base station apparatus and the relay station apparatus, propagation path fluctuation information between the relay station apparatus and the second terminal apparatus, a base station apparatus, The wireless communication system according to claim 2, wherein information on propagation path fluctuation with the second terminal device is included.   4. The relay station apparatus according to claim 1, further comprising an amplifying unit that amplifies the relay signal received by the relay signal receiving unit at a predetermined amplification factor. 5. Wireless communication system. The base station device generates a relay signal by adding a power difference between the signal addressed to the second terminal device and the signal addressed to the first terminal device in the relay signal generating means,
The relay station device extracts each of the signals added from the relay signal in the relay signal transmission means, and based on the signal addressed to the first terminal device and the propagation path information indicating the fluctuation of the propagation path An interference signal for the second terminal apparatus is generated, and a result obtained by subtracting the interference signal from a signal addressed to the second terminal apparatus is retransmitted as a new relay signal to the second terminal apparatus. Item 2. The wireless communication system according to Item 1.   The propagation path information includes information on propagation path fluctuation between the relay station apparatus and the second terminal apparatus and information on propagation path fluctuation between the base station apparatus and the second terminal apparatus. The wireless communication system according to claim 5.   The signal level to be transmitted is adjusted in the base station device or the relay station device so that the transmission level after subtraction of the interference signal is within a certain range. The wireless communication system according to item. A relay station device that relays a signal transmitted from a base station device, a first terminal device that communicates directly with the base station device, and a second terminal device that communicates with the base station device via the relay station device In a base station apparatus connected to a wireless communication system configured to include:
A terminal-addressed signal generating means for generating a signal addressed to the first terminal device and a signal addressed to the second terminal;
Relay signal generating means for generating a relay signal by subtracting or adding signals addressed to the two terminals;
A signal transmission means for transmitting the relay signal generated by the relay signal generation means to the relay station apparatus, and transmitting a signal addressed to the first terminal apparatus after transmitting the relay signal to the relay station apparatus;
A base station apparatus comprising:   The relay signal generating means generates an interference signal for the second terminal apparatus based on a signal addressed to the first terminal apparatus and propagation path information representing a propagation path change, and a signal addressed to the second terminal apparatus The base station apparatus according to claim 8, wherein a relay signal is generated by subtracting the interference signal from the base station apparatus.   9. The relay signal generating means generates a relay signal by adding a signal addressed to the second terminal device and a signal addressed to the first terminal device with a power difference added. The base station apparatus as described in. In a radio communication system including a base station device and a plurality of terminal devices, in a relay station device that relays a relay signal transmitted from the base station device to the terminal device,
When the signal addressed to the first terminal device that communicates directly with the base station device and the signal addressed to the second terminal device that communicates via the relay station are added to the relay signal, A signal destined for the first terminal device and a signal destined for the second terminal device are respectively extracted, and the second terminal device is based on the signal destined for the first terminal device and the propagation path information indicating the fluctuation of the propagation path. A relay station apparatus that generates an interference signal for the second terminal apparatus and subtracts the signal from the signal addressed to the second terminal apparatus and relays the signal to the second terminal apparatus. A base station apparatus; a relay station apparatus that relays a signal transmitted from the base station apparatus; a first terminal apparatus that directly communicates with the base station apparatus; and the base station apparatus that relays the relay station apparatus; A wireless communication method in a wireless communication system including a second terminal device that performs communication of
The base station apparatus generates a signal addressed to the first terminal apparatus and a signal addressed to the second terminal, generates a relay signal by subtracting or adding the signals addressed to the two terminals, and generates the relay signal. Transmitting a signal to the relay station apparatus, transmitting the relay signal to the relay station apparatus and then transmitting a signal addressed to the first terminal apparatus;
In the relay station apparatus, the relay signal transmitted from the base station apparatus is received, and the base station apparatus transmits the signal addressed to the first terminal apparatus, and the relay signal is transmitted to the second terminal apparatus. A wireless communication method characterized by transmitting to a destination.