KR101318997B1 - Apparatus and method for retrnasmission in multi-hop relay wireless communication system - Google Patents

Abstract

The present invention relates to an apparatus and method for retransmitting a signal using a relay station in a multi-hop relay wireless communication system. The present invention relates to a process for receiving a signal from a base station and a retransmission request signal from a terminal. And confirming a signal to be retransmitted to the terminal through a signal, and transmitting the signal to be retransmitted to the terminal, wherein the RS does not transmit all PDUs received from the transmitting station to the receiving station. Since the receiving station transmits only PDUs not received from the transmitting station, there is an advantage of increasing channel yield.

Multi-hop relay, relay station, hierarchical constellation, retransmission

Description

Retransmission apparatus and method in a multi-hop relay wireless communication system {APPARATUS AND METHOD FOR RETRNASMISSION IN MULTI-HOP RELAY WIRELESS COMMUNICATION SYSTEM}

1 is a diagram illustrating a signal flow for providing a service using a multi-hop relay method in a typical wireless communication system.

2 illustrates a hierarchical constellation diagram according to a modulation scheme according to an embodiment of the present invention;

3 is a diagram illustrating a procedure for mapping transmission data to a symbol according to an embodiment of the present invention;

4 is a diagram illustrating a procedure for mapping transmission data to a symbol according to another embodiment of the present invention;

5 is a schematic diagram of transmitting a signal in a wireless communication system using a multi-hop relay method according to an embodiment of the present invention;

6 is a diagram illustrating an operation procedure of a relay station for retransmitting data according to an embodiment of the present invention;

7 is a diagram illustrating a procedure for retransmitting data according to an embodiment of the present invention;

8 is a block diagram of a base station for transmitting data according to the present invention;

9 is a block diagram of a relay station for receiving data according to the present invention; and

10 is a diagram illustrating a procedure for retransmitting data in a wireless communication system using a multi-hop relay method according to an exemplary embodiment of the present invention.

The present invention relates to an apparatus and method for retransmitting data in a wireless communication system, and more particularly to an apparatus and method for retransmitting data using a relay station in a multi-hop relay wireless communication system. .

In the fourth generation communication system, which is the next generation communication system, studies are being actively conducted to provide individual subscribers with services having various quality of service (Qos) having a transmission speed of about 100Mbps or more.

In the fourth generation communication system, very small radius cells are installed to enable high-speed communication and to accommodate a larger amount of communication. In this case, it is expected that a centralized design using the current wireless network design method is not possible. Accordingly, the fourth generation communication system should be able to actively cope with environmental changes such as the addition of a new base station while being distributedly controlled and constructed. That is, in order to provide an efficient service in a wireless environment in which traffic distribution or call demand is changed, it is possible to use a relay service that delivers data in a multi-hop form by using neighboring terminals or relay stations.

The multi-hop relay wireless communication system can quickly reconfigure the network in response to changes in the communication environment, and more efficiently operate the entire wireless network. In addition, by providing a relay station between the base station and the terminal to configure a multi-hop relay path through the relay station, it is possible to provide a more excellent radio channel to the terminal. Furthermore, by using the multi-hop relay path, it is possible to provide a high-speed data channel to terminals in an area where communication with the base station is not possible, such as a shaded area, thereby expanding the cell area.

1 illustrates a signal flow for providing a service using a multi-hop relay method in a conventional wireless communication system.

As shown in FIG. 1, the terminals 140, 150, 160, and 170 included in the multi-hop relay wireless communication system are connected to the base station 100 through the relay stations 110, 120, and 130. Receive service.

That is, the terminals 140 and 150 included in the cell region 110 of the base station 100 communicate with the base station 100 using the direct terminal link L1. In this case, the terminal 2 150 located in the cell boundary region of the base station 100 having a poor channel state receives a high speed data channel using the relay terminal link L2 of the relay station 2 130.

In addition, the terminals 160 and 170 located outside the cell area 101 of the base station 100 are provided with the service of the base station 100 through the relay terminal link L3 of the relay station 1110. In other words, the base station 100 uses the relay station 1 110 to provide services to the terminals 160 and 170 located outside the cell area to expand the cell area. In addition, the terminal 4 (170) having a poor channel state in a cell boundary area within the service area of the relay station 1 (110) may increase the transmission capacity by using the terminal link (L4) of the relay station 2 (120). have.

As described above, the wireless communication system provides a control channel and a high speed data channel to a terminal located in a cell boundary region and a shaded region having poor channel state by using a multi-hop relaying technique through a relay station. However, as described above, when the transmitting station (base station) transmits a signal to the relay station and the receiving station (terminal) receives the signal from the relay station, transmission efficiency may be reduced. For example, when the transmitting station transmits a signal to the relay station, when the receiving station receives the signal, a procedure for relaying the signal from the relay station to the receiving station becomes unnecessary. In addition, when an error occurs in a signal transmitted from the transmitting station to the relay station, the information having the error is transmitted to the receiving station, thereby causing a waste of resources.

Accordingly, an object of the present invention is to provide an apparatus and method for performing a retransmission of a signal by feeding back status information of a signal received from a transmitting station to a relay station in a receiving station of a multi-hop relay wireless communication system.

Another object of the present invention is to provide an apparatus and method for receiving a signal according to a channel state by performing multiple modulation using a hierarchical constellation of a transmission signal in a multi-hop relay wireless communication system.

Another object of the present invention is to provide an apparatus and method for performing signal retransmission by feeding back a demodulation level of a received signal in a multi-hop relay wireless communication system.

According to a first aspect of the present invention for achieving the above object, an operation method of a relay station for providing a relay service in a multi-hop relay wireless communication system, the process of receiving a signal from the base station, and a retransmission request signal from the terminal When receiving, characterized in that it comprises the step of checking the signal to be retransmitted to the terminal through the retransmission request signal, and transmitting the signal to be retransmitted to the terminal.

According to a second aspect of the present invention, a relay station apparatus for supporting a relay service in a multi-hop relay wireless communication system includes: a receiving unit receiving a signal from a base station, and receiving a retransmission request signal from the terminal; And a retransmission control unit for checking a signal to be retransmitted from the signal and a transmission unit for transmitting the retransmission signal to the terminal.

According to a third aspect of the present invention, an operation method of a terminal for retransmitting a signal in a multi-hop relay wireless communication system includes: receiving a signal from a base station and determining whether an error of the received signal occurs; And checking the received signal without error, and transmitting the information of the received signals to the relay station.

According to a fourth aspect of the present invention, in a multi-hop relay wireless communication system, a terminal apparatus includes a receiver for receiving a signal from a base station, and a retransmission controller for determining a signal for retransmission by determining whether an error of the received signal occurs. And a transmitting unit for transmitting the information of the signal for receiving retransmission determined by the retransmission control unit to the relay station.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Hereinafter, a technique for retransmitting a signal by configuring a frame using hierarchical constellation in a multi-hop relay wireless communication system according to the present invention will be described. In the following description, a relay station for providing a high speed data channel to a terminal located in an outside of a service area of the base station having a poor channel state will be described as an example. That is, the terminal may be poor in channel condition, but may be directly connected to the base station to receive data from the base station.

In the following description, in order to vary the robustness of the error of each physical layer PDU (Physical Protocol Data Unit: PHY PDU) to vary the robust information about the error of each bit in all symbols. Use constellation mapping. That is, two bits of Most Significant Bits (MSBs) among the bit strings corresponding to each symbol are used to distinguish one, two, three, and four quadrants in the constellation plane. In addition, the next 2 bits are used to distinguish 1, 2, 3, and 4 quadrants again in each corresponding quadrant divided into 2 bits of the MSB.

As described above, the MSB 2 bits perform symbol division at the largest level, while the LSB (Least Significant Bit) 2 bits are used to distinguish the nearest symbols. Thus, the bit stream located on the MSB side is robust to channel error, while the bit stream located on the LSB side is weak to channel error. That is, the bit position corresponding to each symbol is fixed according to the degree of robustness to the error, and thus the degree of robustness to the error is determined according to the position of each bit in the bit string corresponding to each symbol.

For example, as shown in FIG. 2, in the case of 16QAM (Quadrature Amplitude Modulation), MSB 2 bits indicate which quadrant 1, 2, 3, or 4 quadrants belong to, and the next 2 bits are divided into the MSB 2 bits. It represents which quadrant of the quadrant contained in each said quadrant. In other words, when the MSB 2 bits are "10", it represents four quadrants, and if it is "00", it represents one quadrant and it is a bit resistant to an error. Here, the adjacent symbols are set such that only one bit is different from each other in a gray mapping scheme.

In the following description, when a transmitting station transmits data, bits of each symbol are robust to errors so that both a relay station having a good channel condition and a receiving station having a bad channel condition can adaptively receive the PDU for each channel condition. It is classified according to and used to transmit different PDUs. Therefore, in order to transmit one PDU as shown in FIGS. 3 and 4, data is transmitted using bits that are similar in error robustness in several symbols.

3 illustrates a procedure of mapping transmission data to a symbol according to an embodiment of the present invention. The description below assumes using 64QAM.

As illustrated in FIG. 3, each of the PHY PDUs 303, 313, and 323 included in the transmission group determines the robustness of the error according to the importance, and according to the robustness of the determined error. Map PHY PDUs 303, 313, 323 to a symbol. For example, the robustness of the error in the transmission group transmits the PHY PDU1 303 to the error most robustly, the PHY PDU2 313 to the second most robustly, and transmits the PHY PDU3 323 to the error. Assume the weakest transmission. Accordingly, the PHY PDU1 303 maps to the MSB 2 bits of each symbol and maps the PHY PDU2 313 to the next 2 bits of the MSB 2 bits. In addition, the PHY PDU3 323 maps to LSB 2 bits. Therefore, in any channel environment, the PHY PDU1 303 has a higher reception success probability than the PHY PDU2 313 or the PHY PDU3 323.

4 illustrates a procedure of mapping transmission data to a symbol according to another embodiment of the present invention. The description below assumes using 256QAM.

As shown in FIG. 4, the robustness of the error according to the importance of the PHY PDUs 401, 403, 405, and 407 is the strongest for the PHY PDU1 401, and then the PHY PDU2 403 and PHY PDU2. 405, and finally, PHY PDU3 (407). Thus, the PHY PDU1 401 maps to the MSB 2 bits of each symbol, and the PHY PDU2 403 maps to the next 2 bits after the MSB 2 bits. The PHY PDU3 405 also maps to the next two bits of the two bits that the PHY PDU2 403 matched, and the PHY PDU4 407 maps to two bits of LSB.

As described above, the PHY PDU is mapped to a specific bit string of each symbol to transmit a PHY PDU with a constant degree of error. Therefore, when the PHY PDU consists of n bits, the PHY PDU is transmitted using n / 2 symbols.

As shown in FIGS. 3 and 4, when each PDU forms and transmits a frame having robustness against various levels of error by using a hierarchical constellation, each PDU has a constant degree of error and thus a channel Can be adaptively adapted to the situation. That is, when the channel condition is poor, only the PHY PDU having the best robustness to the error can be received.

5 is a schematic diagram of transmitting a signal in a wireless communication system using a multi-hop relay method according to an embodiment of the present invention.

Referring to FIG. 5, first, the base station 501 configures data such that each PDU has robustness against various levels of errors using hierarchical constellations as shown in FIGS. 3 and 4. And transmits to the terminal 505 (steps 511 and 512).

The RS 503 determines whether an error has occurred in each of the PDUs included in the data received from the BS 501, and determines a demodulation level (MCS) of successfully received PDUs without error. Thereafter, the demodulation level is transmitted to the base station 501. For example, when the base station 501 transmits data using 64QAM, three PDUs of 2 bits are included in one symbol. At this time, if all three PDUs are successfully received without error, since all 6 bits for the three PDUs must be demodulated, the demodulation level is determined by 64QAM. On the other hand, if only two PDUs are successfully received without error, since the 4 bits for the two PDUs must be demodulated, the demodulation level is determined by 16QAM.

Thereafter, the base station 501 retransmits the data using the demodulation level information received from the relay station 503. For example, when data is transmitted using 64QAM, if a demodulation level of 16QAM is received from the RS 503, it is determined that a PDU corresponding to 2 bits of LSB is not received and the PDU for the 2 bits of LSB is determined. Resend. In this case, the retransmitted PDU may be transmitted by changing the strength of the error.

The terminal 505 determines whether an error occurs in each of the PDUs included in the data received from the base station 501, and determines a demodulation level (Modulation and Coding Scheme (MCS) level) of the PDUs successfully received without errors. The demodulation level is then sent to the relay station 503. For example, when the base station 501 transmits data using 64QAM, three PDUs of 2 bits are included in one symbol. At this time, if two PDUs are successfully received without error, since the 4 bits for the two PDUs must be demodulated, the demodulation level is determined by 16QAM. On the other hand, if only one PDU is successfully received without error, since two bits for the one PDU must be demodulated, the demodulation level is determined by QPSK.

Thereafter, the RS 503 checks the PDU to be retransmitted according to the demodulation level information received from the MS 505, and if the PDUs to be retransmitted have been successfully received from the BS 501 without error, the PDUs are received from the MS. Retransmission is performed. For example, when the base station 501 receives data transmitted using 64QAM without error, if a demodulation level of QPSK is received from the terminal 505, a PDU corresponding to 4 bits is not received from the LSB. Determine that the PDUs are retransmitted. In this case, the retransmitted PDU may be transmitted by changing the strength of the error.

6 is a flowchart illustrating an operation procedure of a relay station for retransmitting data according to an embodiment of the present invention.

Referring to FIG. 6, the RS 503 first checks whether a signal is received from the BS 501 in step 601.

If the signal is received, the RS 503 proceeds to step 603 to determine whether the PDUs included in the received signal have been successfully received to determine a demodulation level (MCS level). In other words, the demodulation level for demodulating successful PDUs without error is determined by checking the CRC of each PDU included in the received signal to determine whether an error occurs. For example, when two PDUs among the PDUs included in one symbol are successfully received, the demodulation level is determined as 16QAM.

After determining the demodulation level, the RS 503 proceeds to step 605 and transmits the determined demodulation level to the base station 501. Although not shown, the RS 503 retransmits PDUs not received from the BS 501 according to the demodulation level transmitted to the BS 501.

In step 607, the RS 503 checks whether a retransmission request signal is received from the MS 505. Here, the retransmission request signal includes a demodulation level of data received by the terminal 505 from the base station 501.

When the retransmission request signal is received, the RS 503 proceeds to step 609 to check the demodulation level of the terminal 505 that has received the data of the base station 501 included in the retransmission request signal, and to retransmit the PDU. Check the information. For example, assuming that data using 64QAM is received from the base station 501, the relay station 503 receives a signal consisting of 6 bits in one symbol. Thus, the one symbol includes information of three PDUs. In this case, when the demodulation level of the QPSK is received from the terminal 505, the RS 503 may use only the MSB 2 bits having the best robustness to an error among the signals received by the terminal 505 from the BS 501. It is judged that the reception was successful. Accordingly, the RS 503 identifies a PDU for retransmitting PDUs corresponding to 4 bits from the LSB.

In step 611, the RS 503 determines whether the PDU to be retransmitted can be retransmitted. That is, it is checked whether the PDUs to be retransmitted are received without error from the base station 501. If the PDUs are not received, the relay station 503 terminates this algorithm.

On the other hand, if the PDUs to be retransmitted are normally received without error, the RS 503 transmits the PDUs to the UE 505 in step 613. Here, the retransmitted PDU may be transmitted by changing the strength of the error.

The relay station 503 then terminates this algorithm.

7 illustrates a procedure for retransmitting data according to an embodiment of the present invention.

Referring to FIG. 7, first, the base station 701 configures data to have a robust degree against various errors as shown in FIG. 3 or 4 and transmits the data to the relay station 703 and the terminal 705 (step 711). .

When data is received from the base station 701 and the relay station 703 and the terminal 705, the CRC of each PDU included in the received data checks whether an error occurs.

After checking whether the PDUs have an error, the RS 703 determines a demodulation level for demodulating the received PDUs without error and transmits the demodulation level to the BS 701 (step 713). In addition, the terminal 705 determines the demodulation level for demodulating the received PDUs without error and transmits the demodulation level to the relay station 703 (step 715).

Thereafter, the base station 701 checks the PDUs that the relay station 703 has not received through the demodulation level received from the relay station 703 and retransmits them to the relay station 503 (step 717).

In addition, the RS 703 identifies a PDU that the UE 705 has not received through the demodulation level received from the UE 705. Thereafter, among the PDUs that the terminal 705 did not receive, the relay station 703 retransmits the PDUs normally received from the base station 701 to the terminal 705 (step 719).

Hereinafter, the block configuration of the base station or the relay station for generating and transmitting data such that the PDUs have various robustness against errors and the block configuration of the relay station or the terminal for receiving and decoding the data will be described. Here, since the base station and the relay station generating and transmitting data such that the PDUs have various stiffnesses for errors have the same block configuration, the operation of the base station and the relay station will be described using the apparatus shown in FIG. 8. In addition, since the relay station and the terminal for receiving and decoding the data have the same block configuration, the operation of the relay station and the terminal will be described using the apparatus shown in FIG. 9.

8 is a block diagram of a base station (or relay station) for transmitting data according to the present invention.

As illustrated in FIG. 8, the base station (or relay station) includes a media access control (MAC) PDU reception buffer 801, a CRC generator 803, an encoder 805, and a PHY PDU transmission buffer 807. And a multiple modulator 809 and a retransmission control unit 811.

First, when using the M-QAM, the MAC PDU reception buffer 801 sets and outputs log ₂ (M) / 2 PDUs as one group. The CRC generator 803 generates and adds a CRC for each n PDUs (= log ₂ (M) / 2) provided from the MAC PDU reception buffer 801 to check whether an error occurs.

The coder 805 encodes and outputs the PDUs having the n number and the CRC generator 803 added with CRC according to a predetermined code rate. The PHY PDU transmission buffer 807 buffers the PDUs provided from the encoder 805 to map the corresponding symbols. In addition, the PHY PDU transmission buffer 807 transmits the corresponding PDU to the multiple modulator 809 according to the PDU information to be retransmitted provided from the retransmission control unit 811.

The retransmission control unit 811 checks demodulation levels received from the relay station (or terminal) and checks PDU information not received by the relay station (or terminal). For example, when the PDUs are transmitted using 64QAM in the multiplex modulator 809, if a demodulation level of 16QAM is received from the RS (or UE), it is determined that a PDU corresponding to 2 bits of LSB is not received. To retransmit the PDU for the LSB 2 bits.

The multiplex modulator 809 uses the hierarchical constellation diagram to provide the PDUs received from the PHY PDU transmission buffer 807 so that each PDU has various error stiffness as shown in FIG. 3 or 4. Configure and print. In addition, the multiple modulator 809 may transmit the PDUs retransmitting by changing the strength of the error.

Referring to the operation of the base station, the PDUs are modulated to have various error stiffnesses and output to the RS and the UE. Thereafter, PDUs not received at the RS are identified and retransmitted according to the demodulation level received from the RS.

Next, referring to the operation of the relay station, the terminal identifies and retransmits PDUs not received from the base station according to the demodulation level received from the terminal.

9 shows a block configuration of a relay station (or terminal) for receiving data according to the present invention.

As illustrated in FIG. 9, the RS (or UE) receives a multiple demodulator 901, a PHY PDU reception buffer 903, a decoder 905, a CRC checking unit 907, a retransmission control unit 909, and a MAC PDU reception. And a buffer 911.

First, the multiple demodulator 901 demodulates a signal received from the base station according to a differentiated demodulation scheme of resources allocated to each group. The PHY PDU reception buffer 903 buffers the demodulated signal at the multiple demodulator 901.

The decoder 905 decodes each PDU received from the PHY PDU reception buffer 903 according to the respective code rate. The CRC checker 907 checks the CRCs of the PDUs decoded by the decoder 905 to check whether PDUs have an error.

The retransmission control unit 909 determines the demodulation level for demodulating the PDU in which the error confirmed by the CRC checking unit 907 does not occur and transmits the demodulation level information to the base station (or relay station). For example, when two PDUs among the received PDUs are successfully received without error, the demodulation level is determined as 16QAM.

The MAC PDU reception buffer 911 stores the PDUs in which the error does not occur in the CRC checker 907 and transmits the PDUs to the upper layer.

First, referring to the operation of the relay station, it is determined whether the PDUs received from the base station have an error, and the demodulation level of the received PDUs without error is determined and transmitted to the base station.

Next, referring to the operation of the terminal, by checking the presence or absence of the PDUs received from the base station to determine the demodulation level of the received PDUs without error and transmits to the RS.

The above embodiment has been described assuming two hops in a multi-hop relay wireless communication system, but it is equally applicable to three or more hops as shown in FIG. 10.

10 illustrates a procedure for retransmitting data in a wireless communication system using a multi-hop relay method according to an embodiment of the present invention.

As shown in FIG. 10, the base station transmits PDUs having robustness against various errors to the relay stations and the terminal. In this case, the RSs and the UE receive only the PDUs received without errors among the PDUs, and only the RS 1 feeds back the received information to the base station (step 1001). Here, the feedback information includes a demodulation level of the PDUs.

Upon receiving the feedback information, the base station identifies and retransmits the PDUs in which the error occurs in the relay station 1. When retransmitting the PDUs, the information robust to the error of each PDU may be changed and retransmitted (step 1003).

Subsequently, the relay station 1 receives the PDU information successfully received by the relay station 2 from the base station without error and transmits only the PDUs not received by the relay station 2. At this time, according to the transmission result, the relay station 1 receives the feedback information to the relay station 2 and retransmits if retransmission is necessary.

Thereafter, the above-described process is repeatedly performed until the terminal successfully receives all signals transmitted by the base station without error.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but is capable of various modifications within the scope of the invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, in a multi-hop relay wireless communication system, PDUs (Protocol Data Units) having robustness against various errors transmitted by a transmitting station are received and adaptively received by the receiving station. By performing retransmission through the relay station, the relay station does not transmit all PDUs received from the transmitting station to the receiving station, but transmits only PDUs that the receiving station does not receive from the transmitting station, thereby increasing the channel yield. have.

Claims (21)

In the operation method of a relay station for providing a relay service in a multi-hop relay wireless communication system, Receiving a signal from a base station, Checking a signal to be retransmitted to the terminal through the retransmission request signal when the retransmission request signal is received from the terminal; Transmitting the signal to be retransmitted to the terminal; Receiving a signal from the base station, Determining whether an error occurs in the received signal when a signal is received from the base station; Determining a demodulation level for demodulating the signals in which the error does not occur; And feeding back the demodulation level to the base station. delete The method of claim 1, And after the feedback of the demodulation level, receiving the error signal among the received signals from the base station again. The method of claim 1, The signal received from the base station, characterized in that each protocol data unit (PDU) included in the signal is configured to have a robustness (Robust) for various errors (Error). The method of claim 1, The retransmission request signal comprises demodulation level information determined by the terminal to demodulate signals in which no error has occurred among the signals received from the base station. 6. The method of claim 5, The process of confirming the retransmission signal, Checking the received demodulation level to identify protocol data unit (PDU) information which is not received by the terminal among the signals received from the base station. The method of claim 1, The process of transmitting the signal to be retransmitted to the terminal, Checking whether the signal to be retransmitted has been received without error from the base station; And when the signal to be retransmitted is received without error, transmitting the retransmission signal to the terminal. The method of claim 1, The signal transmitted to the terminal, And converting the signal into a PDU (Protocol Data Unit) that is stronger in error than the signal received from the base station. A relay station apparatus for supporting a relay service in a multi-hop relay wireless communication system, Receiving unit for receiving a signal from the base station, A retransmission controller which checks a signal to be retransmitted from a signal received from the base station when a retransmission request signal is received from the terminal; A transmitter for transmitting the signal to be retransmitted to the terminal, The receiver may further comprise: A signal receiver for receiving a signal from the base station; An error occurrence checking unit for determining whether an error of the received signal occurs; And a retransmission control unit which determines a demodulation level for demodulating signals for which no error has been confirmed by the error occurrence confirmation unit and feeds back to the base station. delete 10. The method of claim 9, The signal received from the base station is characterized in that each protocol data unit (PDU) included in the signal is configured to have a robustness (Robust) for a variety of errors (Error). 10. The method of claim 9, And the retransmission request signal includes demodulation level information determined by the terminal to demodulate signals having no error among the signals received from the base station. 13. The method of claim 12, The retransmission control unit, And checking the received demodulation level to determine a signal not received by the terminal among the signals received from the base station. 10. The method of claim 9, The transmitting unit, And converting the signal to be retransmitted into a protocol data unit (PDU) that is more resistant to errors than the signal received from the base station. A method of operating a terminal for retransmitting a signal in a multi-hop relay wireless communication system, Receiving a signal from a base station, Determining whether the received signal has an error and checking the received signal without an error; Transmitting information of the received signals to a relay station, And the information on the received signals includes demodulation level information for demodulating signals for which no error has occurred by determining whether an error occurs in the received signal. 16. The method of claim 15, The signal received from the base station is characterized in that each protocol data unit (PDU) included in the signal is configured to have a robustness (Robust) for a variety of errors (Error). delete 16. The method of claim 15, And transmitting information of the received signals to a relay station, and then retransmitting a signal having an error among the signals received from the base station from the relay station. A terminal device in a wireless communication system of a multi-hop relay method, Receiving unit for receiving a signal from the base station, A retransmission controller for determining a signal for retransmission by determining whether an error of the received signal occurs; A transmitting unit for transmitting information of a signal for receiving retransmission determined by the retransmission control unit to a relay station, The retransmission control unit, And determining a demodulation level for demodulating signals having no error by determining whether an error occurs in the received signal and feeding back a feedback signal. delete The method of claim 19, The signal received from the base station, characterized in that each PDU (Protocol Data Unit) is configured to have a robust (Robust) for various errors (Error).

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