JP5042144B2 - Wireless relay transmission system, relay station apparatus, and wireless relay transmission method - Google Patents

Description

The present invention relates to a radio relay transmission systems, medium Tsugikyoku apparatus for performing data transmission by radio by the relay, and a radio relay transmission method.

A conventional wireless relay transmission system will be described with reference to FIG. In the radio relay transmission system shown in the figure, the relay station R1 relays and transmits the radio signal received from the transmission station Tx toward the destination station Rx. In the case of the regenerative relay system, the relay station R1 performs relay transmission to the destination station Rx after decoding the signal received from the transmission station Tx (see, for example, Non-Patent Document 1). The wideband signal (a) transmitted from the transmitting station Tx undergoes frequency selective fading due to the propagation path to the relay station R1, and therefore the relay station R1 receives the wideband signal (b) of the affected frequency spectrum. Will do. The relay station R1 decodes the received wideband signal (b), returns it to a flat power wideband frequency spectrum such as the wideband signal (c), and retransmits it. Since frequency selective fading occurs in the propagation path to Rx, the destination station Rx receives a wideband signal (d) of the frequency spectrum of the affected power.
J. Laneman, DNCTse, GWWorrell, "Cooperative diversity in Wireless Networks: Efficient Protocols and Outage Behavior", IEEE Trans. On IT, Vol. 50, No. 12, Dec. 2004

  In the prior art described above, the system throughput of the entire wireless relay transmission system depends on the worse of the signal-to-noise power ratio between the transmitting station Tx and the relay station R1 or between the relay station R1 and the destination station Rx. Resulting in. Therefore, when the signal-to-noise power ratio between the relay station R1 and the destination station Rx is poor, even if communication from the transmission station Tx to the relay station R1 is successful, an error occurs in the communication between the relay station R1 and the destination station Rx. Occurs, and the system throughput is reduced.

This problem will be described with reference to FIG. In the wireless relay transmission system shown in the figure, a multicarrier signal is transmitted, and the transfer function of the propagation path between the transmitting station Tx and the relay station R1 is H _Tx-R1 , and the propagation between the relay station R1 and the destination station Rx. Let the transfer function of the path be _HR1-Rx . The transfer function indicates the reception power (power) on the receiving side for each frequency corresponding to the subcarrier or the subcarrier. Then, in subcarriers with higher received power than a threshold at which multiple modulation schemes can be communicated without error, 16QAM (Quadrature Amplitude Modulation) with higher multiplicity is used, and there are many subcarriers corresponding to transfer functions with lower received power than the threshold. It is assumed that data is modulated by QPSK (Quadrature Phase Shift Keying), which is low in severity.

As shown in the figure, in the transfer function _HR1-Rx , the received power of the subcarriers 5 and 6 is lower than the threshold value, but the transmitting station Tx knows only the transfer function _HTx-R1 and The function _HR1-Rx is not grasped. According to the transfer function H _Tx-R1 that the transmitting station Tx knows, the received power of the subcarriers 5 and 6 exceeds the threshold value, so that a sufficient multiplex number modulation can be ensured to ensure sufficient power. A signal is transmitted using a method. However, even if the relay station R1 relays and transmits with the high multiplex number transmitted from the transmitting station Tx, the high multiplex number is communicated between the relay station R1 and the destination station Rx for the subcarriers 5 and 6. Therefore, the probability that an error will occur becomes very high because the necessary power cannot be secured. In this way, the signal reception quality of the entire wireless relay transmission system is governed by the worse signal-to-noise power ratio in the propagation path by way of the relay station R1. As a result, processing such as a re-transmission request occurs, and the communication efficiency becomes very poor.

The present invention has been made in consideration of such circumstances, and the object of the present invention is to make an error between any devices when a relay station wirelessly relays a multicarrier signal from a transmission station to a destination station. radio relay transmission system that can reduce the probability of occurrence, middle Tsugikyoku apparatus, and aims to provide a radio relay transmission method.

The present invention has been made to solve the above-described problems, and includes a transmission station apparatus, a destination station apparatus, and one or more relay stations that relay a multicarrier radio signal transmitted from the transmission station apparatus to the destination station apparatus. In the wireless relay transmission system comprising the device, the transmitting station device uses the wireless means for transmitting and receiving signals wirelessly and the training signal received from the relay station device by the wireless means of the transmitting station device. A transfer function estimating means for estimating a transfer function in a propagation path with a station apparatus, and a power value corresponding to each subcarrier obtained from the transfer function estimated by the transfer function estimating means of the transmitting station apparatus. Determining means for determining the number of multiplexes to be used for each subcarrier corresponding to the power value, and the transmission information sequence according to the multiplex number determined by the determining means; Multiplex modulation means for modulating each rear, and orthogonal modulation means for orthogonally modulating the subcarriers modulated by the multiplex modulation means to generate a multicarrier signal and transmitting by the wireless means of the transmitting station apparatus, The relay station device includes a wireless unit that wirelessly transmits and receives a signal, a training signal generation unit that generates a training signal and transmits the training signal by the wireless unit of the relay station device, and the wireless unit of the relay station device Transfer function estimation means for estimating a transfer function in a propagation path with a transmission source device of the training signal using a training signal received from the other relay station device or the destination station device on the station device side; Corresponding to each subcarrier in the relay signal from the transfer function estimated by the transfer function estimating means of the relay station device A relay multiplex number determining means for acquiring a force value and determining a multiplex number to be used for each subcarrier corresponding to the acquired power value, and the transmitting station apparatus or the transmitting station apparatus by the radio means of the relay station apparatus Demodulating means for demodulating the multicarrier signal received from the other relay station apparatus on the side, the multiplex number of each subcarrier demodulated by the demodulating means, and the relay signal determined by the relay multiplex number determining means The demodulated subcarrier is switched so that the number of multiplexed subcarriers matches, and the subcarrier switching means for generating subcarrier replacement information indicating the replaced subcarrier, and the subcarrier switching means Is modulated with the subcarrier replacement information together with the subcarrier replacement information. Re-modulation means to be transmitted by the wireless means, the destination station apparatus is a wireless means for transmitting and receiving signals wirelessly, and a training signal generating means for generating a training signal and transmitting the training signal by the wireless means of the destination station apparatus Demodulating a multicarrier signal received from the relay station device by the radio means of the destination station device to obtain a received information sequence, and a received information sequence of each subcarrier demodulated by the demodulating device. And a signal rearrangement unit that replaces a reception information sequence corresponding to the replaced subcarrier based on the subcarrier replacement information received from the relay station device by the wireless unit of the destination station device. This is a wireless relay transmission system.

  Further, the present invention is the above-described wireless relay transmission system, wherein the relay station device generates a signal indicating the transfer function estimated by the transfer function estimation unit of the relay station device, and is addressed to the transmitting station device A transfer function receiving means for receiving a signal indicating a transfer function estimated in the relay station apparatus that does not directly transmit / receive a radio signal to / from the transmitting station apparatus. The determination unit of the transmission station apparatus further includes an estimation in each relay station apparatus indicated by a transfer function estimated by the transfer function estimation unit of the transmission station apparatus and a signal received by the transfer function reception unit. For each of the transferred functions, a power value corresponding to each subcarrier is acquired, and multiplexing is used for each subcarrier corresponding to the acquired power value. Further, the subcarriers to be exchanged in the relay station apparatus are specified so that the number of multiplexed subcarriers of the received signal and the number of multiplexed subcarriers of the relay transmission signal are the same in each relay station apparatus. Then, replacement information is generated and transmitted to the relay station apparatus, and the subcarrier replacement means of the relay station apparatus replaces each subcarrier demodulated by the demodulation means according to the received replacement information. And

  The present invention also relates to a wireless relay transmission system comprising a transmission station device, a destination station device, and one or more relay station devices that relay a multicarrier radio signal transmitted from the transmission station device to the destination station device. In the relay station apparatus, a wireless means for transmitting and receiving a signal wirelessly, a training signal generating means for generating a training signal and transmitting it by the wireless means, and the other relay station apparatus on the destination station apparatus side by the wireless means or Using the training signal received from the destination station apparatus, transfer function estimation means for estimating a transfer function in a propagation path between the training signal transmission apparatus and the transfer function estimated by the transfer function estimation means The power value corresponding to each subcarrier in the relay signal is acquired and used for each subcarrier corresponding to the acquired power value. A relay multiplexing number determining means for determining a multiplexing number; a demodulating means for demodulating a multicarrier signal received from the transmitting station apparatus or another relay station apparatus on the transmitting station apparatus side by the radio means; and The demodulated subcarriers are switched and switched so that the multiplex number of each demodulated subcarrier matches the multiplex number of each subcarrier in the relay signal determined by the relay multiplex number determining means. Subcarrier replacement means for generating subcarrier replacement information indicating a subcarrier, and a signal in which subcarriers are replaced by the subcarrier replacement means are modulated and transmitted by the radio means of the relay station apparatus together with the subcarrier replacement information And a re-modulation means, That.

  In addition, the present invention is used in a radio relay transmission system including a transmission station apparatus, a destination station apparatus, and one or more relay station apparatuses that relay a multicarrier radio signal transmitted from the transmission station apparatus to the destination station apparatus. The transmission station apparatus, the destination station apparatus, and the transmission station apparatus include wireless means for transmitting and receiving signals wirelessly, and the training signal generation means of the relay station apparatus includes: A relay station training signal generating process for generating a training signal and transmitting the training signal by the wireless unit of the relay station device, and a training signal generating unit of the destination station device generating a training signal, and the wireless of the transmitting station device Destination station training signal generation process to be transmitted by means, and transfer function estimation means of the transmitting station apparatus, the wireless means of the transmitting station apparatus A transmission station transfer function estimation process for estimating a transfer function in a propagation path with the relay station apparatus using the training signal received from the relay station apparatus, and a determination unit of the transmission station apparatus comprising: A determination process of acquiring a power value corresponding to each subcarrier from the transfer function estimated in the transfer function estimation process, and determining a multiplex number to be used for each subcarrier corresponding to the acquired power value; and A multiplex modulation means for modulating a transmission information sequence for each subcarrier according to the multiplex number determined in the determination process; and a subcarrier modulated by the orthogonal modulation means of the transmitting station apparatus in the multiplex modulation process. Is orthogonally modulated to generate a multi-carrier signal and transmitted by the wireless means of the transmitting station apparatus, and transmission of the relay station apparatus. The function estimation means uses the training signal received from the other relay station apparatus on the destination station apparatus side or the destination station apparatus by the wireless means of the relay station apparatus, and with the transmission source apparatus of the training signal The relay station transfer function estimation process for estimating the transfer function in the propagation path between the relay station apparatus and the relay multiplex number determining means of the relay station apparatus from the transfer function estimated in the relay station transfer function estimation process to each subcarrier in the relay signal A relay multiplex number determination step of acquiring a corresponding power value and determining a multiplex number to be used for each subcarrier corresponding to the acquired power value; and a demodulation unit of the relay station device, A relay station demodulation process for demodulating a multicarrier signal received from the transmitting station apparatus or another relay station apparatus on the transmitting station apparatus side by means, and the relay station The re-modulating means of the apparatus is such that the multiplex number of each subcarrier demodulated in the relay station demodulation process matches the multiplex number of each subcarrier in the relay signal determined in the relay multiplex number determination process. The demodulated subcarriers are replaced, and a subcarrier replacement process for generating subcarrier replacement information indicating the replaced subcarriers, and a remodulation unit of the relay station apparatus replaces the subcarriers in the subcarrier replacement process. Remodulation process in which the received signal is modulated and transmitted by the radio means of the relay station apparatus together with the subcarrier replacement information, and the demodulation means of the destination station apparatus is transmitted by the radio means of the destination station apparatus. Demodulation process to obtain the received information sequence by demodulating the multicarrier signal received from the device The signal rearranging means of the destination station apparatus uses the subcarrier replacement information received from the relay station apparatus by the radio means of the destination station apparatus for the received information sequence of each subcarrier demodulated in the demodulation process. And a signal rearrangement process for exchanging received information sequences corresponding to the replaced subcarriers.

  According to the present invention, in a radio relay transmission system, the probability that an error occurs in any propagation path between a transmission station device and a relay station device, between a relay station device and a relay station device, or between a relay station device and a destination station device. And the system throughput can be improved.

  Embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment]
FIG. 1 is a diagram showing a configuration of a wireless relay transmission system according to a first embodiment of the present invention. In the figure, the wireless relay transmission system transmits from a transmission station Tx that wirelessly transmits a multicarrier signal, a relay station R1 that wirelessly relays a signal transmitted from the transmission station Tx to the destination station Rx, and the transmission station Tx. It consists of a destination station Rx that is a destination of the multicarrier signal. In addition, although the case where there is one relay station is shown here, a plurality of relay stations may be provided. In the figure, (a) the frequency spectrum when the relay station R1 receives a multicarrier radio signal transmitted with flat power from the transmission station Tx, and the propagation path between the transmission station Tx and the relay station R1. the transfer function H _Tx-R1, and, (b) from the relay station R1 and the frequency spectrum when the multi-carrier radio signal relayed by the flat power received at the destination station Rx, the relay station R1 and the destination station Rx The transfer function _HR1-Rx of the propagation path is shown. This transfer function indicates reception power (power) on the receiving side for each subcarrier or for each frequency corresponding to the subcarrier.

In the present embodiment, the transmission station Tx knows in advance the transfer function H _Tx-R1 between the transmission station Tx and the relay station R1 and the transfer function H _R1-Rx between the relay station R1 and the destination station Rx. Thus, the transmitting station Tx selects an appropriate multiplex modulation corresponding to these transfer functions for each subcarrier to generate a multicarrier signal. For example, as shown in (a), for subcarriers 4 and 8, the signal-to-noise power ratio in the propagation path between the transmitting station Tx and the relay station R1 is poor, so that the received power is an error in a multiplex modulation scheme. Since the signal-to-noise power ratio in the propagation path between the relay station R1 and the destination station Rx is poor for the subcarriers 5 and 6, as shown in FIG. Is lower than the aforementioned threshold. In this case, the transmitting station Tx previously generates and transmits a multicarrier signal for subcarriers 4, 5, 6, and 8 by applying a multiplex modulation scheme with a smaller number of multiplexing than other subcarriers.

Next, each device constituting the wireless relay transmission system according to the present embodiment will be described.
FIG. 2 is a block diagram showing an internal configuration of the transmission station Tx according to the present embodiment. The transmitting station Tx includes a multiplex modulation circuit 10, a training signal generation / addition circuit 11, a quadrature modulation circuit 12, a radio unit 13, a switch 14, an antenna 15, a transfer function estimation circuit 16, a transfer function storage device 17, and a threshold determination circuit 18. Prepare.

The multiplex modulation circuit 10 modulates a transmission information sequence for each subcarrier by a multiplex modulation method according to the number of multiplexes for each subcarrier instructed by the threshold determination circuit 18. Examples of the multiplex modulation method include QPSK (Quadrature Phase Shift Keying), 16QAM (Quadrature Amplitude Modulation), and 64 QAM. The training signal generation / addition circuit 11 generates a predetermined training signal for obtaining the transfer function H _Tx- R1 in the relay station R1 and adds it to the transmission signal. The quadrature modulation circuit 12 performs quadrature modulation on subcarriers to generate a multicarrier signal. The radio unit 13 converts the multicarrier signal generated by the quadrature modulation circuit 12 into a radio signal.

The switch 14 switches whether to transmit the radio signal generated by the radio unit 13 through the antenna 15 or to output the reception signal from the antenna 15 to the transfer function estimation circuit 16. The transfer function estimation circuit 16 estimates the transfer function H _Tx-R1 from the received multicarrier radio signal. In addition, the transfer function estimation circuit 16 acquires a transfer function _HR1-Rx by data communication received from the relay station R1. The transfer function storage device 17 stores the transfer function H _Tx-R1 estimated by the transfer function estimation circuit 16 and the transfer function H _R1-Rx received from the relay station R1. Based on the transfer functions _HTx-R1 and _HR1-Rx stored in the transfer function storage device 17, the threshold determination circuit 18 determines whether or not the received power of each subcarrier exceeds the threshold corresponding to the multiplexing number. Is determined, and the multiplexing number to be applied to each subcarrier is instructed to the multiplex modulation circuit 10 based on the result.

  FIG. 3 is a block diagram showing the internal configuration of the relay station R1 according to this embodiment. The relay station R1 includes an antenna 20, a switch 21, a transfer function estimation circuit 22, a transfer function storage device 23, a demodulator 24, a remodulator 25, a training signal generation / addition circuit 26, and a radio unit 27.

The switch 21 switches whether the signal received by the antenna 20 is output to the transfer function estimation circuit 22 or the radio signal generated by the radio unit 27 is transmitted by the antenna 20. The transfer function estimation circuit 22 estimates the transfer function H _Tx-R1 from the training signal received from the transmission station Tx and the transfer function H _R1-Rx from the training signal received from the destination station Rx. The transfer function storage device 23 stores the transfer function H _Tx-R1 estimated by the transfer function estimation circuit 22 and the transfer function H _R1-Rx . The demodulator 24 demodulates the received signal using a transfer function corresponding to the transmission source.

The remodulator 25 modulates the reception signal demodulated by the demodulator 24. The training signal generation / addition circuit 26 generates a predetermined training signal for obtaining the transfer function H _Tx-R1 at the transmission station Tx and the transfer function H _R1-Rx at the destination station Rx, and adds it to the transmission signal. To do. The training signal generation / addition circuit 26 generates a data signal for notifying the transmission station Tx of the transfer function _HR1-Rx . The radio unit 27 is a radio signal that is modulated by the remodulator 25 and is a multi-carrier signal to which the training signal is added by the training signal generation / addition circuit 26 and a data communication signal for notifying the transfer function _HR1-Rx. Convert to

  FIG. 4 is a block diagram showing the internal configuration of the destination station Rx according to this embodiment. The destination station Rx includes an antenna 30, a switch 31, a transfer function estimation circuit 32, a transfer function storage device 33, a demodulator 34, a training signal generation / addition circuit 35, and a radio unit 36.

The switch 31 switches whether the antenna 30 outputs a reception signal to the transfer function estimation circuit 32 or transmits the radio signal generated by the radio unit 36 via the antenna 30. The transfer function estimation circuit 32 estimates the transfer function _HR1-Rx from the received training signal. The transfer function storage device 33 stores the transfer function _HR1-Rx estimated by the transfer function estimation circuit 32. The demodulator 34 demodulates the received signal using the transfer function _HR1-Rx to obtain a received information sequence. The training signal generation / addition circuit 35 generates a predetermined training signal for obtaining the transfer function _HR1-Rx in the relay station R1, and adds it to the transmission signal. The radio unit 36 converts the multicarrier signal to which the training signal is added in the training signal generation / addition circuit 26 into a radio signal.

Note that the transmission / reception timing of the training signal between the transmission station Tx and the relay station R1, and between the relay station R1 and the destination station Rx, and the transfer function based on the data signal between the relay station R1 and the transmission station Tx. The transmission / reception timing of _HR1-Rx is determined in advance. For example, when the transfer function H _R1-Rx is notified from the relay station R1 to the transmission station Tx, the data signal for the transfer function H _R1-Rx is placed behind the training signal, and the data signal for actual communication is placed behind the data signal. Use a communication frame that puts.

FIG. 5 is a processing flow showing the operation of the wireless relay transmission system according to the present embodiment.
In the figure, a multiplex modulation circuit 10 of a transmission station Tx divides a transmission information sequence into serial and multiplex-modulates each subcarrier, and a training signal generation / addition circuit 11 performs a known training with the relay station R1. A signal is generated and added to the signal that is multiplex-modulated for each subcarrier by the multiplex modulation circuit 10. The quadrature modulation circuit 12 quadrature modulates the subcarrier signal to which the training signal is added by the training signal generation / addition circuit 11 to generate a multicarrier signal. The radio unit 13 converts the multicarrier signal generated by the orthogonal modulation circuit 12 into a radio signal, and this radio signal is transmitted from the antenna 15 (step S105).

The transfer function estimation circuit 22 of the relay station R1 estimates the transfer function H _Tx-R1 from the difference between the training signal included in the radio signal received from the transmission station Tx and the known training signal, and stores it in the transfer function storage device 23. Write (step S110). The demodulator 24 of the relay station R1 demodulates the received signal using the transfer function _HTx-R1, and then the remodulator 25 modulates the received signal demodulated by the demodulator 24. The training signal generation / addition circuit 26 generates a known training signal with respect to the destination station Rx and adds it to the remodulated signal. The radio unit 27 converts the multicarrier signal modulated by the remodulator 25 and added with the training signal in the training signal generation / addition circuit 26 into a radio signal, and this radio signal is transmitted from the antenna 20 to the destination station Rx. The Further, the training signal generation / addition circuit 26 of the relay station R1 generates a training signal based on a known multicarrier signal with the transmission station Tx and adds it to the transmission signal addressed to the transmission station Tx. The radio unit 27 converts the transmission signal to which the training signal is added in the training signal generation / addition circuit 26 into a radio signal, and this radio signal is transmitted from the antenna 20 to the transmission station Tx (step S115).

The transfer function estimation circuit 32 of the destination station Rx estimates the transfer function _HR1-Rx from the difference between the training signal included in the received radio signal and the known training signal, and writes it in the transfer function storage device 33. Further, the transfer function estimation circuit 16 of the transmitting station Tx estimates the transfer function H _Tx-R1 from the difference between the training signal included in the received radio signal and the known training signal, and writes it in the transfer function storage device 17 ( Step S120). The demodulator 34 of the destination station Rx demodulates the received signal using the transfer function H _R1-Rx to obtain a received information sequence.

  Subsequently, the training signal generation / addition circuit 35 of the destination station Rx generates a known multicarrier training signal with the relay station R1 and adds it to the transmission signal addressed to the relay station R1. The radio unit 36 converts the transmission signal to which the training signal is added in the training signal generation / addition circuit 35 into a radio signal, and this radio signal is transmitted from the antenna 30 to the relay station R1 (step S125).

Transfer function estimation circuit 22 of the relay station R1 estimates a training signal included in the radio signal received from the destination station Rx, the transfer function H _R1-Rx from the deviation between the known training signal, the transfer function storage device 23 Write (step S130). The training signal generation / addition circuit 26 generates a data communication signal indicating the transfer function _HR1-Rx estimated by the transfer function estimation circuit 22. Usually, since a data signal is inserted after the training signal, the numerical information of the estimated transfer function _HR1-Rx is placed on the data signal portion and modulated. The radio unit 27 converts the data communication signal in which the transfer function _HR1-Rx is set in the training signal generation / addition circuit 26 into a radio signal, and this radio signal is transmitted from the antenna 20 to the transmission station Tx (step S135). ).

The transfer function estimation circuit 16 of the transmitting station Tx demodulates the received radio signal to obtain the transfer function H _Tx-R1 and writes it in the transfer function storage device 17 (step S140). The threshold determination circuit 18 initializes the variable i with 0 and initializes the variable n to a value when the multiplexing number ²ⁿ is the maximum value (steps S145 and S150). Then, when the threshold value determination circuit 18 updates the current value of i to a value obtained by adding 1 (step S155), the transfer function storage device 17 transmits the transfer corresponding to the subcarrier i (or the frequency used by the subcarrier i). The values of the function _HTx-R1 and the transfer function _HR1-Rx are read out, and any smaller value is selected (step S160). The threshold determination circuit 18 determines whether or not the received power of the subcarrier i indicated by the selected smaller value is equal to or greater than a threshold at which the multiplexing number 2 ⁿ can be transmitted (step S165). It is assumed that the threshold that can transmit the multiplexing number ²ⁿ is held in the threshold determination circuit 18 in advance.

When the power value acquired in step S160 is smaller than the threshold value that can transmit the multiplexing number 2 ⁿ , the threshold value determination circuit 18 updates the current n value to a value obtained by subtracting 1 (step S170). Then, the determination in step S165 is performed again.

When the power value acquired in step S160 is ^equal to or greater than the threshold value that can transmit the multiplexing number 2 ⁿ , the threshold value determination circuit 18 associates the current i value with the current n value, and determines the threshold value. The data is stored in the storage means included in the circuit 18 (step S175). The threshold determination circuit 18 determines whether or not processing has been performed for all i up to the number of subcarriers (step S180), and if not completed yet, repeats the processing from step S150. Then, n is stored for all the subcarriers i, and when the processing is completed, the threshold determination circuit 18 outputs all the subcarriers i and the multiplex number 2 ⁿ (or n) corresponding to each i to the multiplex modulation circuit 10. To do. The multiplex modulation circuit 10 multiplex-modulates the information signal sequence according to the multiplex number 2 ⁿ corresponding to the subcarrier i output from the threshold determination circuit 18, and the transmitting station Tx uses the multiplex-modulated subcarrier signal from the multiplex modulation. The generated multicarrier radio signal is transmitted (step S185).
The relay station R1 relays the multicarrier radio signal transmitted from the transmission station Tx in step S185 by the same processing as in the conventional technique, and transmits it to the destination station Rx.

  The above processing is applicable regardless of the number of relay stations and the number of antennas. In other words, in a wireless relay transmission system composed of a transmitting station, one or more relay stations, and a destination station, each station transmits and receives a training signal, measures the transfer function of the transmission path on the transmitting side and the receiving side of its own station, Transmit the measured transfer function to the transmitting station. When the transmitting station transmits a multicarrier signal, the minimum transfer function is selected for each subcarrier from the transfer function measured at the transmitter station and the received transfer function, and the subcarrier is selected based on the selected transfer function. Determine the number of multiple modulations for the carrier.

For example, when there are relay stations R1 to Rn, the relay station Rk (k = 1 to n) receives the training received from the relay station R (k-1) (in the case of the relay station R1, the transmission station Tx). Based on the signal, the transfer function of the propagation path between the relay station R (k−1) and the relay station Rk is estimated, and the training received from the relay station R (k + 1) (destination station Rx in the case of the relay station Rk) Based on the signal, the transfer function of the propagation path between the relay station Rk and the relay station R (k + 1) is estimated. Also, the destination station Rx estimates the transfer function of the propagation path between the destination station Rx and the relay station Rn based on the training signal received from the relay station Rn. The relay station Rk (k = 1 to n) transmits the transfer function of the propagation path between itself and the subsequent relay station R (k + 1) (in the case of the relay station Rk, the destination station Rx) by data communication. Notify Tx as the destination. At this time, the data communication signal transmitted from the relay stations R2 to Rn is relayed by another relay device and transmitted to the transmission station Tx. The transmitting station Tx stores the received transfer function in the transfer function storage device 17.
After step S145, the same processing as in FIG. 5 is performed, but in step S160, the threshold value determination circuit 18 of the transmitting station Tx is a value corresponding to subcarrier i from all transfer functions stored in the transfer function storage device 17. Choose the value of the transfer function with the smallest.

In a conventional wireless relay transmission system, when the signal-to-noise power ratio between the relay station and the destination station is smaller than the signal-to-noise power ratio between the transmitting station and the relay station and does not satisfy a certain threshold, a retransmission request due to communication failure is made. Is likely to occur.
However, according to the present embodiment described above, the transfer function of the propagation path between the devices to be relayed in advance is acquired at the transmitting station, and the subcarrier is determined according to the signal-to-noise power ratio in the relay route to the destination station. By setting a rate (multiplex number) for each transmission and transmitting, it is possible to reduce the occurrence of a retransmission request due to communication failure, and a simple error correction code can be used. As a result, throughput can be improved.

[Second Embodiment]
Next, a radio relay transmission system according to the second embodiment of the present invention will be described. In this embodiment, the relay station R1 preliminarily sets the transfer function H _Tx-R1 between the transmission station Tx and the relay station R1 and the transfer function H _R1-Rx of the propagation path between the relay station R1 and the destination station Rx. By grasping, in the relay station R1, appropriate subcarrier signals are exchanged according to both transfer functions. Note that the wireless relay transmission system according to the present embodiment has the same connection configuration as the wireless relay transmission system of the first embodiment.

  FIG. 6 is a diagram for explaining a subcarrier signal replacement process. For example, as shown in (a), since the signal-to-noise power ratio between the transmitting station Tx and the relay station R1 is poor for the subcarriers 4 and 8, the received power communicates with a certain multiplex modulation system without error. Since the signal-to-noise power ratio between the relay station R1 and the destination station Rx is poor for the subcarriers 5 and 6, as shown in FIG. Below threshold. At this time, the relay station R1 replaces the signals of the subcarriers 4 and 8 in the multicarrier signal received from the transmission station Tx with the subcarriers 5 and 6 when the relay signal is transmitted from the relay station R1. Subcarrier replacement information indicating which subcarrier is replaced by which subcarrier is notified to the destination station Rx using a pilot carrier or a predetermined subcarrier, and the destination station Rx is in accordance with the notified replacement information, Decoding is performed by replacing the subcarriers.

  When the transmitting station Tx knows the transfer function of the propagation path between the relay station R1 and the destination station Rx, by adding subcarrier replacement information to the pilot signal or the like from the transmitting station Tx, It is also possible to reduce the processing of the relay station R1 by placing some processing burden on the transmitting station Tx side. The method for the transmitting station Tx to grasp the transfer function of the propagation path between the relay station R1 and the destination station Rx is the same as in the first embodiment.

Next, each device constituting the wireless relay transmission system according to the present embodiment will be described.
FIG. 7 is a block diagram showing an internal configuration of the transmission station Tx according to the present embodiment. In this figure, the same parts as those of the transmitting station Tx of the first embodiment shown in FIG. The transmission station Tx shown in FIG. 7 is different from the transmission station Tx of the first embodiment in that instead of the transfer function estimation circuit 16, the transfer function storage device 17, and the threshold value determination circuit 18, a transfer function estimation circuit 16a and a transfer function are provided. The storage device 17a and the threshold determination circuit 18a are provided.

The transfer function estimation circuit 16a estimates the transfer function H _Tx-R1 from the received multicarrier radio signal. The transfer function storage device 17a stores the transfer function H _Tx-R1 estimated by the transfer function estimation circuit 16a. Based on the transfer function H _Tx-R1 stored in the transfer function storage device 17a, the threshold determination circuit 18a determines whether or not the received power of each subcarrier exceeds the threshold corresponding to the multiplex number, Based on the result, the multiple modulation scheme to be applied to each subcarrier is instructed to the multiple modulation circuit 10.

FIG. 8 is a block diagram showing an internal configuration of the relay station R1 according to the present embodiment. In the figure, the same parts as those of the transmission station Tx of the first embodiment shown in FIG. The relay station R1 shown in FIG. 8 is different from the relay station R1 of the first embodiment in that a threshold determination circuit 28 and a subcarrier switching circuit 29 are provided.
Based on the transfer function _HR1-Rx estimated by the transfer function estimation circuit 22, the threshold determination circuit 28 determines whether or not the received power of each subcarrier exceeds the threshold corresponding to the multiplex number. The number of multiplexed subcarriers is determined based on the determination result. The subcarrier switching circuit 29 receives the subcarrier received from the transmitting station Tx and demodulates the subcarrier so that the subcarrier multiplexing number and the relay signal subcarrier multiplexing number are the same. The carriers are switched and output to the remodulator 25. Further, the subcarrier switching circuit 29 inserts switching information into a pilot signal or the like addressed to the destination station Rx.

  FIG. 9 is a block diagram showing the internal configuration of the destination station Rx according to this embodiment. In this figure, the same parts as those in the destination station Rx of the first embodiment shown in FIG. The relay station R1 shown in FIG. 9 is different from the relay station R1 of the first embodiment in that a signal rearrangement circuit 37 is provided. The signal rearrangement circuit 37 replaces the reception information sequence corresponding to the subcarrier according to the replacement information with respect to the reception information sequence demodulated by the demodulator 34 to obtain a reception information sequence in the correct order.

FIG. 10 is a processing flow showing the operation of the wireless relay transmission system according to the present embodiment.
The processing in steps S205 to S230 in FIG. 10 is the same as the processing in steps S105 to S130 in the first embodiment shown in FIG. That is, the transmission station Tx transmits a training signal to the relay station R1, and the transfer function estimation circuit 22 of the relay station R1 estimates the transfer function H _Tx-R1 based on the received training signal and transfers the transfer function storage device 23. Write to. The relay station R1 transmits a training signal to the destination station Rx and the transmission station Tx, and the transfer function estimation circuit 32 of the destination station Rx estimates the transfer function _HR1-Rx based on the received training signal and stores the transfer function. Write to device 33. In addition, the transfer function estimation circuit 16a of the transmission station Tx estimates the transfer function H _Tx-R1 based on the received training signal and writes it in the transfer function storage device 17a. Further, the destination station Rx generates a training signal and transmits it to the relay station R1, and the transfer function estimation circuit 22 of the relay station R1 estimates the transfer function _HR1-Rx based on the received training signal and transfers the transfer function. Write to the storage device 23.

The threshold determination circuit 18a of the transmitting station Tx initializes the variable i with 0, and initializes the variable n to a value when the multiplexing number ²ⁿ is the maximum value (steps S235 and S240). Then, when the threshold value determination circuit 18a updates the current value of i to 1 (step S245), the subcarrier i (or subcarrier i) is obtained from the transfer function H _Tx-R1 stored in the transfer function storage device 17a. The power value corresponding to the frequency used by the carrier i is read out, and it is determined whether or not the read power value is ^equal to or greater than a threshold at which the multiplexing number 2 ⁿ can be transmitted (step S250). It is assumed that the threshold that can transmit the multiplexing number ²ⁿ is held in the threshold determination circuit 18a in advance.

When the power value acquired in step S250 is smaller than the threshold value at which the multiplexing number 2 ⁿ can be transmitted, the threshold value determination circuit 18a updates the current n value to a value obtained by subtracting 1 (step S255). Then, the determination in step S250 is performed again.

When the power value acquired in step S255 is ^equal to or greater than the threshold value that can transmit the multiplexing number 2 ⁿ , the threshold value determination circuit 18a associates the current i value with the current n value, and determines the threshold value. The data is stored in the storage means provided in the circuit 18a (step S260). The threshold determination circuit 18a determines whether or not processing has been performed for all i up to the number of subcarriers (step S265), and if not completed yet, repeats the processing from step S235. Then, n is stored for all the subcarriers i, and when the processing is completed, the threshold value determination circuit 18a outputs all the subcarriers i and the multiplex number 2 ⁿ (or n) corresponding to each i to the multiplex modulation circuit 10. To do. The multiplex modulation circuit 10 multiplex-modulates the information signal sequence according to the multiplex number 2 ⁿ corresponding to the subcarrier i output from the threshold determination circuit 18a, and the transmitting station Tx uses the multiplex-modulated subcarrier signal in this way. The generated radio signal is generated (step S270).

The threshold determination circuit 28 of the relay station R1 initializes the variable i ′ with 0, and initializes the variable n ′ to a value when the multiplexing number 2 ^{n ′} is the maximum value (steps S275 and S280). Then, when the threshold value determination circuit 28 updates the current value of i ′ to a value obtained by adding 1 (step S285), the subcarrier i ′ () is transferred from the transfer function _HR1-Rx stored in the transfer function storage device 23. Alternatively, the power value corresponding to the frequency used by the subcarrier i ′ is read out, and it is determined whether or not the read power value is equal to or greater than a threshold at which the multiplexing number 2 ^{n ′} can be transmitted (step S290). It is assumed that the threshold that can transmit the multiplexing number 2 ^{n ′} is held in the threshold determination circuit 28 in advance.

When the value of the power acquired in step S290 is smaller than the threshold that can transmit the multiplexing number 2 ^{n ′} , the threshold determination circuit 18a updates the current value of n ′ to a value obtained by subtracting 1 (step S295). Then, the determination in step S290 is performed again.

When the power value acquired in step S295 is equal to or greater than the threshold value capable of transmitting the multiplexing number 2 ^{n ′} , the threshold determination circuit 28 associates the current i ′ value with the current n ′ value, It memorize | stores in the memory | storage means with which the said threshold value determination circuit 28 is provided (step S300). The threshold determination circuit 28 determines whether or not all i's up to the number of subcarriers have been processed (step S305), and repeats the processing from step S280 if not completed yet. Then, n ′ is stored for all the subcarriers i ′, and when the processing is completed, the threshold determination circuit 28 calculates all the subcarriers i ′ and the multiplex number 2 ^{n ′} (or n ′) corresponding to each i ′. The data is output to the subcarrier switching circuit 29. The subcarrier switching circuit 29 sub-receives the received signal so that the number of multiplexed subcarriers i of the received signal demodulated by the demodulator 24 is the same as the number of multiplexed subcarriers i ′ determined by the threshold determining circuit 28. The carriers are switched and output to the remodulator together with the subcarrier replacement information (step S310). Thereby, the relay station R1 transmits the relay signal in which the subcarriers are switched according to the signal-to-noise power ratio with the destination station Rx and the subcarrier replacement information to the destination station Rx.

  The demodulator 34 of the destination station Rx demodulates the multicarrier signal transmitted from the relay station R1 to obtain a reception information sequence. The signal rearrangement circuit 37 applies the received information sequence demodulated by the demodulator 34 according to the correspondence between the subcarrier i ′ in the relay signal indicated by the exchange information and the subcarrier i in the transmission signal from the transmission station Tx. The received information sequence corresponding to subcarrier i and the received information sequence corresponding to subcarrier i ′ are switched. Thereby, the destination station Rx can acquire the reception information sequence in the correct order.

  Note that the above processing is applicable regardless of the number of relay stations and the number of antennas. That is, in a wireless relay transmission system including a transmission station, one or more relay stations, and a destination station, each station transmits and receives a training signal, measures a transfer function, and transmits a propagation path to the subsequent station after the measurement. The function determines the number of multiplexed modulations for the subcarrier. In each relay station, the received signal subcarriers are switched so that the number of multiplexed subcarriers of the received multicarrier signal is the same as the number of multiplexed subcarriers determined based on the transfer function, and transmitted together with the replacement information. To do. The destination station replaces the reception information series between the subcarriers according to the received replacement information.

  For example, when there are relay stations R1 to Rn, each relay station Rk (k = 1 to n) is connected to the relay station R (k−1) (in the case of the relay station R1, the transmission station Tx) and the relay station Rk. And the transfer function of the propagation path between the relay station Rk and the relay station R (k + 1) (in the case of the relay station Rn, the destination station Rx). The destination station Rx performs the same processing as in FIG. 10, and each relay station Rk (k = 1 to n) performs the same processing as the processing after step S275 described above. However, the transfer function read by each relay station Rk (k = 1 to n) in step S290 is the propagation path between the relay station Rk and the relay station R (k + 1) (in the case of the relay station Rn, the destination station Rx). It is a transfer function, and it is a signal received from the relay station R (k−1) (or the transmission station Tx in the case of the relay station R1) that is the target of subcarrier replacement in step S310.

When the transmitting station Tx generates the replacement information, the operation is as follows. That is, the transmitting station Tx performs the same procedure as in the first embodiment between the relay station Rk (k = 1 to n) and the relay station R (k + 1) (in the case of the relay station Rn, the destination station Rx). Receive the transfer function of the propagation path. Then, the threshold determination circuit 18a of the transmitting station Tx performs the processing of steps S235 to S270 shown in FIG. 10 to determine the number of multiplexed carriers by using the transfer function H _Tx-R1, and then the relay station and the subsequent stage. For each transfer function between the stations, the processes of steps S275 to S305 in FIG. 10 are performed to determine the number of multiplexed carriers. The threshold determination circuit 18a determines whether each relay station Rk (k) has the same number of subcarriers in the received signal and the number of subcarriers in the relay transmission signal at the relay station Rk (k = 1 to n). = 1 to n), a subcarrier to be replaced is specified, and replacement information is generated. The transmitting station Tx performs multi-carrier signal processing in the same manner as in step S270 of FIG. 10, but at this time, the threshold determination circuit 18a adds the generated replacement information to the transmission signal. As a result, the relay station Rk (k = 1 to n) does not perform steps S275 to S305 of FIG. 10 but relays the subcarriers according to the received replacement information.

In a wireless relay transmission system, when the signal-to-noise power ratio between the relay station and the destination station is smaller than the signal-to-noise power ratio between the transmitting station and the relay station and does not satisfy a certain threshold, a retransmission request due to communication failure occurs. The probability of doing is increased.
However, according to the second embodiment, since appropriate subcarrier replacement information is held at the start of communication, it is possible to lighten the relay calculation process and reduce the circuit scale. Further, it is possible to reduce the number of retransmission requests due to communication failure and to use a simple error correction code. As a result, throughput can be improved.

It is a block diagram which shows the structure of the radio relay transmission system by 1st embodiment of this invention. It is a block diagram which shows the internal structure of the transmitting station Tx by the embodiment. It is a block diagram which shows the internal structure of relay station R1 by the embodiment. It is a block diagram which shows the internal structure of the destination station Rx by the embodiment. It is a processing flow of the wireless relay transmission system by the same embodiment. It is a block diagram which shows the operation | movement outline | summary of the radio relay transmission system by 2nd embodiment of this invention. It is a block diagram which shows the internal structure of the transmitting station Tx by the embodiment. It is a block diagram which shows the internal structure of relay station R1 by the embodiment. It is a block diagram which shows the internal structure of the destination station Rx by the embodiment. It is a processing flow of the wireless relay transmission system by the same embodiment. It is a block diagram which shows the structure of the wireless relay transmission system by a prior art. It is a figure for demonstrating the problem in the wireless relay transmission system of a prior art.

Explanation of symbols

Tx: Transmitting station (transmitting station apparatus), R1: Relay station (relay station apparatus), Rx: Destination station (destination station apparatus), 10: Multiple modulation circuit (multiplex modulation means), 11: Training signal generation / addition circuit, DESCRIPTION OF SYMBOLS 12 ... Orthogonal modulation circuit (orthogonal modulation means), 13 ... Radio | wireless part (radio means), 14 ... Switch, 15 ... Antenna, 16, 16a ... Transfer function estimation circuit (Transfer function estimation means, Transfer function receiving means), 17, DESCRIPTION OF SYMBOLS 17a ... Transfer function memory | storage device 18, 18a ... Threshold determination circuit (determination means), 20 ... Antenna, 21 ... Switch, 22 ... Transfer function estimation circuit (transfer function estimation means), 23 ... Transfer function memory device, 24 ... Demodulation (Remodulation means), 25 ... remodulator (remodulation means), 26 ... training signal generation / addition circuit (training signal generation means, transfer function notification means), 27 ... Line part (radio means) 28 ... Threshold judgment circuit (relay multiplex number judgment means) 29 ... Subcarrier replacement circuit (subcarrier replacement means) 30 ... Antenna 31 ... Switch 32 ... Transfer function estimation circuit 33 ... Transfer function storage device 34. Demodulator (demodulation means) 35. Training signal generation / addition circuit (training signal generation means) 36. Radio unit (wireless means) 37 37 Signal rearrangement circuit (signal rearrangement means)

Claims (4)

In a radio relay transmission system including a transmission station device, a destination station device, and one or more relay station devices that relay a multicarrier radio signal transmitted from the transmission station device to the destination station device,
The transmitting station device
Wireless means for transmitting and receiving signals wirelessly;
Transfer function estimating means for estimating a transfer function in a propagation path with the relay station apparatus using the training signal received from the relay station apparatus by the wireless means of the transmitting station apparatus;
Determining means for obtaining a power value corresponding to each subcarrier from the transfer function estimated by the transfer function estimating means of the transmitting station apparatus, and determining a multiplex number used for each subcarrier corresponding to the obtained power value; ,
Multiplex modulation means for modulating the transmission information sequence for each subcarrier according to the multiplexing number determined by the determination means;
A quadrature modulation unit that orthogonally modulates the subcarriers modulated by the multiple modulation unit to generate a multicarrier signal, and transmits the multicarrier signal by the radio unit of the transmission station apparatus,
The relay station device
Wireless means for transmitting and receiving signals wirelessly;
Training signal generating means for generating a training signal and causing the radio means of the relay station apparatus to transmit the training signal;
Using the training signal received from the other relay station device on the destination station device side or the destination station device by the wireless means of the relay station device, in the propagation path between the training signal transmission source device and A transfer function estimating means for estimating a transfer function;
The power value corresponding to each subcarrier in the relay signal is acquired from the transfer function estimated by the transfer function estimating means of the relay station apparatus, and the multiplex number used for each subcarrier is determined corresponding to the acquired power value. Relay multiplex number determination means;
Demodulating means for demodulating a multicarrier signal received from the transmitting station apparatus or another relay station apparatus side by the wireless means of the relay station apparatus;
The demodulated subcarriers are switched so that the number of multiplexed subcarriers demodulated by the demodulating means matches the number of multiplexed subcarriers in the relay signal determined by the relay multiplexed number determining means. Subcarrier replacement means for generating subcarrier replacement information indicating the replaced subcarrier;
Remodulating means for modulating a signal in which subcarriers are replaced by the subcarrier replacing means, and transmitting the modulated signal together with the subcarrier replacement information by the wireless means of the relay station device,
The destination station device is
Wireless means for transmitting and receiving signals wirelessly;
Training signal generating means for generating a training signal and causing the wireless means of the destination station apparatus to transmit the training signal;
Demodulating means for demodulating a multicarrier signal received from the relay station apparatus by the radio means of the destination station apparatus and obtaining a received information sequence;
For the reception information sequence of each subcarrier demodulated by the demodulation means, reception corresponding to the replaced subcarrier based on the subcarrier replacement information received from the relay station apparatus by the radio means of the destination station apparatus Signal rearranging means for exchanging information series,
A wireless relay transmission system. The relay station device further includes a transfer function notification unit that generates a signal indicating the transfer function estimated by the transfer function estimation unit of the relay station device and transmits the signal to the transmission station device,
The transmitting station apparatus further includes transfer function receiving means for receiving a signal indicating a transfer function estimated in the relay station apparatus that does not directly transmit / receive a radio signal to / from the transmitting station apparatus,
The determination means of the transmission station apparatus is a transmission function estimated by each relay station apparatus indicated by a transfer function estimated by the transfer function estimation means of the transmission station apparatus and a signal received by the transfer function reception means. For each of the functions, a power value corresponding to each subcarrier is acquired, a multiplexing number used for each subcarrier is determined corresponding to the acquired power value, and a subcarrier of a received signal in each relay station device To generate the replacement information by specifying the subcarrier to be replaced in the relay station apparatus, so that the multiplexing number of the relay transmission signal and the number of subcarriers of the relay transmission signal are the same, and transmit to the relay station apparatus,
The subcarrier replacement means of the relay station device replaces each subcarrier demodulated by the demodulation means according to the received replacement information.
The wireless relay transmission system according to claim 1 . In the relay station device of the wireless relay transmission system including a transmission station device, a destination station device, and one or more relay station devices that relay a multicarrier radio signal transmitted from the transmission station device to the destination station device,
Wireless means for transmitting and receiving signals wirelessly;
Training signal generating means for generating a training signal and causing the wireless means to transmit the training signal;
Using the training signal received from the other relay station device or the destination station device on the destination station device side by the wireless means, the transfer function in the propagation path with the source device of the training signal is estimated A transfer function estimation means;
A relay multiplex number determining means for acquiring a power value corresponding to each subcarrier in the relay signal from the transfer function estimated by the transfer function estimating means and determining a multiplex number used for each subcarrier corresponding to the acquired power value When,
Demodulating means for demodulating a multicarrier signal received from the transmitting station apparatus or another relay station apparatus on the transmitting station apparatus side by the wireless means;
The demodulated subcarriers are switched so that the number of multiplexed subcarriers demodulated by the demodulating means matches the number of multiplexed subcarriers in the relay signal determined by the relay multiplexed number determining means. Subcarrier replacement means for generating subcarrier replacement information indicating the replaced subcarrier;
Remodulating means for modulating a signal in which subcarriers have been replaced by the subcarrier replacing means, and causing the wireless means of the relay station apparatus to transmit together with the subcarrier replacement information;
A relay station apparatus comprising: A radio relay transmission method used in a radio relay transmission system including a transmission station apparatus, a destination station apparatus, and one or more relay station apparatuses that relay a multicarrier radio signal transmitted from the transmission station apparatus to the destination station apparatus. There,
The transmitting station device, the destination station device, and the transmitting station device include wireless means for transmitting and receiving signals wirelessly,
A relay station training signal generating unit of the relay station device generates a training signal and transmits the training signal by the wireless unit of the relay station device; and
The destination station training signal generation means of the destination station apparatus generates a training signal, and causes the radio means of the transmission station apparatus to transmit the destination station training signal generation process;
Transmission in which the transfer function estimating unit of the transmitting station apparatus estimates a transfer function in a propagation path with the relay station apparatus using the training signal received from the relay station apparatus by the wireless unit of the transmitting station apparatus Station transfer function estimation process,
The determining means of the transmitting station apparatus obtains a power value corresponding to each subcarrier from the transfer function estimated in the transmitting station transfer function estimation process, and a multiplexing number used for each subcarrier corresponding to the acquired power value A determination process for determining
A multiplex modulation means for modulating the transmission information sequence for each subcarrier in accordance with the multiplex number determined in the determination process;
An orthogonal modulation process in which the orthogonal modulation means of the transmitting station apparatus orthogonally modulates the subcarriers modulated in the multiple modulation process to generate a multicarrier signal and transmits the multicarrier signal by the wireless means of the transmission station apparatus;
The transfer function estimating means of the relay station device uses the training signal received from the other relay station device or the destination station device on the destination station device side by the wireless means of the relay station device, and A relay station transfer function estimation process for estimating a transfer function in a propagation path with a source device;
The relay multiplex number determination means of the relay station device acquires a power value corresponding to each subcarrier in the relay signal from the transfer function estimated in the relay station transfer function estimation process, and corresponding to each of the acquired power values A relay multiplex number determination process for determining the multiplex number used for the subcarrier;
A relay station demodulation process in which the demodulation means of the relay station apparatus demodulates a multicarrier signal received from the transmission station apparatus or another relay station apparatus side by the wireless means of the relay station apparatus;
The remodulation means of the relay station apparatus matches the multiplex number of each subcarrier demodulated in the relay station demodulation process with the multiplex number of each subcarrier in the relay signal determined in the relay multiplex number determination process. Replacing the demodulated subcarriers, and generating a subcarrier replacement information indicating the replaced subcarriers,
A re-modulation process in which the re-modulation means of the relay station apparatus modulates a signal in which sub-carriers are replaced in the sub-carrier replacement process, and transmits the modulated signal together with the sub-carrier replacement information by the radio means of the relay station apparatus;
Demodulating means of the destination station apparatus demodulates the multicarrier signal received from the relay station apparatus by the wireless means of the destination station apparatus, and obtains a received information sequence;
Based on the subcarrier replacement information received from the relay station device by the radio unit of the destination station device, the signal rearrangement unit of the destination station device receives the received information sequence of each subcarrier demodulated in the demodulation process. A signal rearrangement process for replacing received information sequences corresponding to the replaced subcarriers;
A wireless relay transmission method comprising:

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