KR101442259B1 - A method of operating a relay in a wireless communication system - Google Patents

Abstract

A method of operating a repeater in a wireless communication system includes decoding a received signal to recover an information packet and obtaining a first probability sequence representing probability information of each information bit constituting the information packet, Obtaining a second probability sequence indicating probability information of each code bit constituting the code packet using the first probability sequence and obtaining a modulation symbol using the second probability sequence do. If the relay has an error in the signal received from the source station, if the error detection of the signal received from the source station is not possible and if the error detection result is unreliable, then the relay can properly transmit the signal to the target station.

Description

A METHOD OF OPERATING A RELAY IN A WIRELESS COMMUNICATION SYSTEM In a wireless communication system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wireless communication, and more particularly, to a method of operating a repeater in a wireless communication system.

The Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard provides techniques and protocols for supporting broadband wireless access. Standardization progressed from 1999 and IEEE 802.16-2001 was approved in 2001. It is based on a single carrier physical layer called 'WirelessMAN-SC'. In the IEEE 802.16a standard approved in 2003, 'WirelessMAN-OFDM' and 'WirelessMAN-OFDMA' were added in addition to 'WirelessMAN-SC' in the physical layer. The IEEE 802.16-2004 standard was revised in 2004 after the IEEE 802.16a standard was completed. IEEE 802.16-2004 / Cor1 (hereinafter referred to as IEEE 802.16e) was completed in 2005 in the form of 'corrigendum' to correct bugs and errors in the IEEE 802.16-2004 standard.

Currently, in order to provide coverage extension and throughput enhancement in the IEEE 802.16 Task Group j (hereinafter referred to as IEEE 802.16j) based on IEEE 802.16e, Relay stations have been introduced and are being standardized. That is, according to the IEEE 802.16j standard, a signal can be transmitted to a terminal outside the base station region through a repeater, and a high-quality (high-quality) signal having a high level of Adaptive Modulation and Coding So that the system capacity can be increased with the same radio resources.

Representative operational modes of the repeater include a decode-and-forward (DF) mode and an amplify-and-forward (AF) mode. According to the DF mode, the wireless repeater recovers transmission information through a process such as demodulation, channel decoding, and error check of a signal received from a source station, Coding) and a modulation process to the target station. Next, according to the AF mode, the wireless repeater amplifies the signal received from the source station, and then transmits the amplified signal to the target station.

The DF mode is capable of removing noise and checking whether there is an error, thereby improving the reliability of signal transmission and changing the channel coding and modulation method in the repeater. However, there is a disadvantage that time delay occurs. On the other hand, the AF mode is advantageous in that the operation of the repeater is simple and the time delay is reduced, but the noise contained in the signal can not be removed and it is impossible to confirm whether or not there is an error.

FIG. 1 is a diagram illustrating a relay procedure according to the AF mode, FIG. 2 is a diagram illustrating a relay procedure according to the DF mode, and is an example of a transparent mode of IEEE 802.16j.

Referring to FIGS. 1 and 2, frame n precedes frame n + 1 (Frame n + 1) in time. One frame includes a downlink (DL) region and an uplink (UL) region. The DL region includes a DL Access Zone and a DL Transparent Zone. The UL region includes an UL Access Zone and an UL Relay Zone Zone. Herein, the downlink access zone is a region in which a base station transmits a signal to a repeater or a terminal, and a downlink transport zone is an area in which a repeater transmits a signal to a terminal. The uplink access zone is a region in which a terminal transmits a signal to a repeater or a base station, and the uplink relay zone is an area in which a repeater transmits a signal to a base station.

In FIG. 1, when a base station transmits a signal to a repeater through a downlink access zone of a frame n, the repeater delivers a signal to the terminal through a downlink transport zone of frame n. In addition, when the base station transmits a signal to the repeater through the downlink access zone of the frame n + 1, the repeater transmits the signal to the terminal through the downlink transport zone of the frame n + 1. As described above, according to the AF mode, the repeater amplifies the signal received from the base station and then transmits the amplified signal to the terminal, so that the signal can be transmitted within the same frame without additional time delay.

On the other hand, in FIG. 2, when a base station transmits a signal to a repeater through a downlink access zone of a frame n, the repeater transmits a signal to a terminal through a downlink transport zone of a frame n + 1. As described above, according to the DF mode, the repeater modulates, decodes, error checks, codes, and modulates a signal received from the base station, so that an additional time delay occurs do. Also, since the sign and modulation scheme are different, the size of the signal can be changed.

In order to compensate for the characteristics of the AF mode and the DF mode as described above, there is an attempt to use the AF mode and the DF mode in combination. For example, the Hybrid AF / DF (Hybrid AF / DF) method transmits information according to the DF mode if it succeeds and the AF mode when it fails. According to this, the target station can reduce the probability of receiving errors by appropriately combining the received signals according to the HARQ scheme or the signals received according to another path according to the AF mode.

The Hybrid AF / DF method is a method of controlling a modulation and coding scheme (MCS) applied to an SR link between a source station and a relay and an RD link Is the same as the MCS applied to the base station. However, in general, the channel state of the S-R link and the channel state of the R-D link are not equal to each other. Therefore, it is desirable to apply different MCSs to the S-R link and the R-D link, and assign different amounts of resources such as bandwidth.

If the MCS applied to both links and the amount of allocated resources are different from each other, the hybrid AF / DF scheme is not effective. This is because the target station can not decode the received signal according to the AF mode since it prepares for decoding according to the MCS predefined in the RD link. Due to this problem, the IEEE 802.16j standard requires that a signal that the repeater fails to receive is discarded without being forwarded to the target station. However, this means that if an error occurs in the SR link, resources previously allocated to the RD link are wasted.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method for a repeater to transmit a signal received from a source station to a target station. In particular, when the MCS level of the S-R link and the R-D link is different from the amount of the allocated resources, a method of transmitting a signal to the target station is proposed.

A method of operating a repeater in a wireless communication system according to an aspect of the present invention includes decoding a received signal to recover an information packet and obtaining a first probability sequence indicating probability information of each information bit constituting the information packet, Obtaining a code packet by encoding the information packet and obtaining a second probability sequence indicating probability information of each code bit constituting the code packet using the first probability sequence; And obtaining a modulation symbol.

A method of operating a repeater in a wireless communication system in accordance with another aspect of the present invention includes decoding a received signal and reconstructing it into an information packet of information bits, selecting at least one suspicious bit among the information bits, Obtaining a code packet by encoding the information packet, and constructing the code packet using the first probability sequence, wherein the first probability sequence includes probability information on the remaining information bits except for the bit and the suspect bit, Obtaining a second probability sequence representing probability information of each code bit, and obtaining a modulation symbol using the second probability sequence.

A method of operating a repeater in a wireless communication system according to another aspect of the present invention includes the steps of decoding a received signal and reconstructing the received signal into a first information packet made up of information bits and inverting a part or all of the suspicious bits Generating at least one second information packet, generating a plurality of code packets by respectively encoding the first information packet and the second information packet, and modulating each of the plurality of code packets to generate a plurality of modulation symbols And averaging the plurality of modulation symbols.

A repeater according to an aspect of the present invention includes a decoder for decoding a received signal to recover an information packet and obtaining a first probability sequence indicating probability information of each information bit constituting the information packet, An encoder for obtaining a second probability sequence indicating a probability of each code bit constituting the code packet using the first probability sequence and a modulator for obtaining a modulation symbol using the second probability sequence do.

According to the present invention, when a relay receives an error in a signal received from a source station, when error detection of a signal received from a source station is impossible, and when it is difficult to reliably detect an error detection result, . In particular, when the MCS levels of the S-R link and the R-D link are different, it is possible to increase the probability of error recovery. Also, when a resource is allocated in advance to the R-D link, resources of the R-D link can be utilized even if an error occurs in the S-R link, thereby preventing waste of resources.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a diagram illustrating a wireless communication system using a repeater. Wireless communication systems are widely deployed to provide various communication services such as voice, packet data, and the like.

3, the wireless communication system includes a mobile station (MS) 10, a base station 20 (BS), and a relay station 30 . The terminals 10, 11, 12 and 13 may be fixed or mobile and may be referred to by other terms such as User Equipment (UE), User Terminal (UT), Subscriber Station (SS) . The base station 20 generally refers to a fixed station that communicates with the terminals 10, 11, 12 and 13 and includes a Node-B, a Base Transceiver System (BTS) Point). One base station 20 may have more than one cell. The repeaters 30 and 31 are located between the terminal and the base station for the purpose of improving the transmission rate due to the extension of the coverage or the diversity effect. That is, the terminals 10 and 11 within the coverage of the base station 20 can communicate directly with the base station 20 and the terminals 12 and 13 outside the coverage of the base station 20 can communicate with the repeaters 30 and 31 And communicates with the base station 20. [ Alternatively, even the terminals 10 and 11 within the coverage of the base station 20 can communicate with the base station 20 via the repeaters 30 and 31 for the purpose of improving the transmission rate due to the diversity effect.

Hereinafter, downlink (DL) means communication from the base station 20 to the terminal 10, and uplink (UL) means communication from the terminal 10 to the base station 20. Therefore, in the downlink, the source station is the base station 20, the destination station is the terminal 10, the source station is the terminal 10, and the target station is the base station 20 in the uplink. In the downlink, the transmitter may be part of the base station 20 and the receiver may be part of the terminal 10. In the uplink, the transmitter may be part of the terminal 10 and the receiver may be part of the base station 20.

The wireless communication system may be an Orthogonal Frequency Division Multiplexing (OFDM) / Orthogonal Frequency Division Multiple Access (OFDMA) based system. OFDM uses multiple orthogonal subcarriers. OFDM uses the orthogonality property between IFFT (Inverse Fast Fourier Transform) and FFT (Fast Fourier Transform). In the transmitter, data is transmitted by performing IFFT. The receiver performs an FFT on the received signal to recover the original data. The transmitter uses an IFFT to combine multiple subcarriers, and the receiver uses a corresponding FFT to separate multiple subcarriers.

4 is a flowchart showing an example of a process in which a signal is transmitted from a source station to a target station through a repeater.

Referring to FIG. 4, the source station channel-encodes an information packet (Information Packet) composed of information bits representing information to be transmitted to the target station (S100). The information packet is converted into a first code packet (Coded Packet) composed of coded bits.

The source station transmits the first code packet to the repeater (S110).

Upon receiving the first code packet from the source station, the repeater channel-decodes the first code packet (S120). The first code packet is reconstructed into an information packet by the channel decoding process.

The repeater checks an error of the information packet restored in step S120 (S130). Here, a parity check, a cyclic redundancy checking (CRC), a header check sum, and the like can be used to check the error of the information packet.

If it is determined in step S130 that there is no error, the repeater demodulates the information packet (S140). Here, it is assumed that the encoder for channel coding in step S100 and the encoder for channel coding in step S140 are different from each other. By the channel encoding process, the information packet is converted into a second code packet composed of code bits.

The repeater modulates the second code packet (S150) and transmits the modulation symbol to the target station (S160).

Here, when there is an error in the received signal of the repeater, the operation method of the repeater becomes a problem. In such a situation, there has been proposed a method in which the repeater does not transmit the received signal to the target station or a method in which the received signal is transmitted to the target station in accordance with the AF mode. However, according to the method of not transmitting the received signal to the target station, resources previously allocated between the R-D links (Relay-Destination Station Link) are wasted. Also, the method of transferring the received signal to the target station according to the AF mode is ineffective because the amount of allocated resources is different between the MCS and the R-D link between the Source Station-Relay Link (S-R) link. Therefore, if there is an error in the received signal, the operation of the repeater will be described below. However, the present invention is not limited to the case where there is an error in the received signal. That is, the present invention can be applied variously when error detection of a received signal is impossible, when an error detection result is unreliable, when a signal is desired to be transmitted in accordance with the AF mode, and the like.

5 is a flowchart illustrating an operation method of a repeater according to an embodiment of the present invention.

Referring to FIG. 5, the repeater receives a first code packet from a source station (S200), and channel decodes the first code packet (S210). The first code packet is reconstructed into an information packet composed of information bits by a channel decoding process. In addition, a probability sequence (first probability sequence) of an information packet indicating probability information of each information bit constituting the information packet can be obtained by a channel decoding process. Here, the probability information means a probability that one information bit is 0 and a probability of one day, and this may be represented by a log likelihood ratio (LLR) that takes a logarithm to a ratio of probability of 0 to probability of one.

Next, an error of the information packet restored in step S210 is checked (S220). Here, a parity check, a cyclic redundancy checking (CRC), a header check sum, and the like can be used to check the error of the information packet.

Next, the repeater channel-encodes the information packet obtained in step S210 (S230). The second code packet can be obtained by the channel encoding process. In addition, a probability sequence (second probability sequence) of the second code packet indicating the probability information of each code bit constituting the second code packet can be obtained by using the probability sequence of the information packet. A specific method of obtaining the probability sequence of the second code packet using the probability sequence of the information packet will be described later.

Next, the repeater calculates each modulation symbol transmitted every transmission time using the probability sequence of the second code packet obtained in step S230 (S240). For example, the modulation symbols can be obtained by grouping the probability sequences of the second code packets according to the modulation scheme between the R-D links, and calculating the probability of each of the ghost points. The modulation symbols are punctured, repetition and reordering based on the probability sequence rate matching and interleaving of the second code packet, and then modulated by the modulation scheme between the RD links , And can be obtained by calculating the probability of each sex shop. A specific method of obtaining the modulation symbol will be described later.

Next, the repeater transmits each modulation symbol obtained in step S240 to the target station every transmission time (S250).

According to FIG. 5, the repeater uses the probability that the signal received from the source station is not a result of hard decision, The modulation symbol is generated according to the result, so that reliability of error recovery can be increased. Also, the repeater transmits a modulation symbol suitable for the amount of pre-allocated resources and a predefined MCS level between RD links to the target station, so that the target station can easily decode and recover the received signal.

Hereinafter, an example of obtaining a probability sequence of a code packet by using a probability sequence of an information packet will be described.

FIG. 6 is a diagram showing an example of a convolutional encoder having a rate of 1/2, and FIG. 7 is a trellis according to the convolutional encoder of FIG. It is assumed that the repeater uses the convolutional encoder of FIG. 6 to transmit the signal to the R-D link.

Referring to FIG. 6, U ₁ , U ₂ , ..., U _n denote the inputs of the convolutional encoder and X ₁ , X ₂ , ..., X _n and Y ₁ , Y ₂ , _n represents the output of the convolutional encoder. The code packets are X ₁ , Y ₁ , X ₂ , Y ₂ , ..., X _n , and Y _n . Referring to FIG. 7, U _k is the k-th information bit in the information packet, X _k , Y _k are the two code bits corresponding to U _k , S _k is the k-th state of the convolutional code . 7, the condition that the state S _{k + 1} becomes 0 is when the previous state S _k is 0 and the previous input U _k is 0, or when the previous state S _k is 1 and the previous input U _k is 0.

Herein, the input to the convolutional encoder is a probability of each information bit constituting the information packet being zero and a probability of one day. Therefore, by using the probability sequence of the information packet and Equation (1), the probability of the state changing according to the input can be obtained.

In addition, a probability sequence of a code packet can be obtained using the probability of each state and the probability sequence of information packets obtained from Equation (1). Equation (2) below shows a method of obtaining code bits X _k and Y _k constituting a probability sequence of code packets.

In this way, the probability sequence of the code packet can be obtained from the probability sequence of the information packet. Here, a method of using a convolutional encoder to obtain a probability sequence of code packets is exemplified, but the present invention is not limited thereto. That is, a person skilled in the art can use a low density parity check (LDPC) coder or a turbo coder to obtain a probability sequence of code packets based on the contents of the present specification.

Hereinafter, an example of obtaining a modulation symbol using a probability sequence of code packets will be described.

FIG. 8 shows a constellation diagram of a quadrature phase shift keying (QPSK) modulation scheme and a method of obtaining a modulation symbol according to an embodiment of the present invention. Here, a QPSK modulation scheme is used to obtain a modulation symbol, but the present invention is not limited thereto. That is, BPSK (Binary Phase Shift Keying), QAM (Quadrature Amplitude Modulation) or the like may be used to obtain modulation symbols.

Referring to FIG. 8, a method for obtaining a modulation symbol from a probability sequence of a code packet using the convolutional encoder of FIG. 6 will be described. Here, the probability that the 2k-1th code bit among the code bits constituting the code packet is 1 is P ( _Xk = 1), and the probability of 0 is P ( _Xk = 0). The probability that the 2kth code bit is 1 is P (Y _k = 1), and the probability of 0 is P (Y _k = 0).

The modulation symbol to be transmitted in the first transmission time can be obtained by using the first code bit and the second code bit in the code packet. Therefore, the probability of each QPSK constellation point of the kth modulation symbol is P (00) = P ( _Xk = 0) * P ( _Yk = 0) P (01) = P (X k = 0) * P (Y k = 1), P (10) = P (X k = 1) * P (Y k = 0) and P (11) = P (X _k = 1) * P (Y _k = 1). Each modulation symbol to be transmitted at each transmission time can be obtained as the sum of the values obtained by multiplying the coordinates of the property store by the probability of the property store. That is, assuming a QPSK modulation scheme, each modulation symbol to be transmitted for each transmission time is [1,1] * P (00) + [1, -1] * P (01) + [ P (10) + [-1, -1] * P (11).

If the distance between the modulation symbol obtained by multiplying the coordinates of the gustation store and the probability of the gustation store is less than a predetermined value, the repeater transmits the modulation symbol corresponding to the one gustation store to the corresponding transmission point To the target station. For example, as shown in FIG. 8, if the distance (d _min ) between the modulation symbol obtained by multiplying the coordinates of the sagittal point by the probability of the sagg store and the [1, 1] , 1] to the target station.

9 is a flowchart illustrating an operation method of a repeater according to another embodiment of the present invention.

Referring to FIG. 9, the repeater receives the first code packet from the source station (S300) and channel decodes the first code packet (S310). The first code packet is reconstructed into an information packet composed of information bits by a channel decoding process. In addition, the channel decoding process can obtain the probability of 0 and the probability of 1 of each information bit constituting the information packet.

Next, in step S320, a suspicious bit among information bits constituting the reconstructed information packet is selected (S320). For example, the suspect bit may be selected using the probability of each information bit being 0 and the probability of one day. That is, the difference between the probability of 0 and the probability of 1 is calculated for each information bit, and the information bit whose difference is less than or equal to a certain value can be set as a suspect bit. Alternatively, a small number of information bits having the smallest difference between the 0-day probability and the 1-day probability may be set as a suspect bit.

Next, the repeater obtains a probability sequence of the information packet (first probability sequence) (S330). Here, the probability sequence of the information packet can be obtained by using the information about the probability of 1 and the probability of each of the information bits obtained in step S310 being 0 and the suspect bit retrieved in step S320. For example, the probability of 0-day probability and 1-day probability of a suspect bit may be 0.5, and the probability of a bit having a higher probability of remaining information bits other than a suspect bit may be 1. [

Next, an error of the information packet restored in step S310 is checked (S340). Here, a parity check, a cyclic redundancy checking (CRC), a header check sum, and the like can be used to check the error of the information packet.

Next, the repeater channel-encodes the information packet obtained in step S310 (S350). The second code packet can be obtained by the channel encoding process. Further, a probability sequence (second probability sequence) of the second code packet indicating the probability of one code bit and the probability of one code bit constituting the second code packet can be obtained by using the probability sequence of the information packet.

Next, the repeater obtains each modulation symbol for each transmission time using the probability sequence of the second code packet obtained in step S340 (S360), and transmits the modulation symbol to the target station (S370).

The method of obtaining the probability sequence of the second code packet in step S350 and the method of obtaining the modulation symbol in step S360 may refer to the methods illustrated in FIG. 6 to FIG.

According to Fig. 9, the repeater uses the probability to transfer the signal received from the source station to the target station The modulation symbol is generated according to the result, so that reliability of error recovery can be increased. Also, the repeater transmits a modulation symbol suitable for the amount of pre-allocated resources and a predefined MCS level between RD links to the target station, so that the target station can easily decode and recover the received signal.

10 is a flowchart illustrating an operation method of a repeater according to another embodiment of the present invention.

Referring to FIG. 10, the repeater receives the first code packet from the source station (S400) and channel decodes the first code packet (S410). The first code packet is reconstructed into a first information packet including information bits by a channel decoding process. In addition, the channel decoding process can obtain the probability of 0 and the probability of 1 of each information bit constituting the information packet.

Next, at step S410, at least one second information packet is generated using the channel decoding result (S420). The second information packet may be obtained by inverting some or all of the suspicious bits among the information bits constituting the first information packet. For example, if the suspect bit is 0, it is inverted to 1, and if it is 1, it can be inverted to 0. Here, for each information bit constituting the first information packet, a difference between a probability of 0 and a probability of 1 may be calculated, and the information bit whose difference is less than or equal to a predetermined value may be set as a suspect bit.

The first information packet may comprise a plurality of suspect bits. The second information packet may be generated by inverting some or all of the plurality of suspect bits. Here, it is possible to generate various second information packets according to the combination of the doubting bits to be inverted. For example, a plurality of second information packets can be generated using a combination of two suspect bits.

Next, the first information packet and the second information packet are respectively channel-coded (S430). The first information packet and the second information packet are converted into a plurality of second code packets by the channel encoding process.

Next, the second code packets are modulated (S440). By modulating the second code packets, a plurality of modulation symbols can be generated at each modulation symbol transmission time point. Here, some of the plurality of second code packets may be used for generation of modulation symbols. For example, only a second code packet generated by inverting two suspect bits among a plurality of second code packets can be used for generation of a modulation symbol. Alternatively, the second code packet generated by inverting one of the plurality of second code packets may be excluded from the generation of the modulation symbol. Alternatively, only a predetermined number of second code packets out of the plurality of second code packets may be used for generation of modulation symbols.

Next, the average modulation symbols are averaged by averaging the plurality of modulation symbols generated at each modulation symbol transmission time (S450).

Next, the average modulation symbol is transmitted to the target station at each modulation symbol transmission time point (S460).

According to FIG. 10, the repeater transmits the average modulation symbols for various cases to the target station, thereby increasing the reliability of error recovery. Further, even when an error occurs in the signal received from the source station, the signal is transmitted to the target station, so that resources previously allocated between the R-D links can be not wasted.

11 is a block diagram of a wireless repeater in accordance with an embodiment of the present invention.

Referring to FIG. 11, the wireless repeater 100 may include a decoder 110, an encoder 120, and a modulator 130.

For example, the decoder 110 of the wireless repeater 100 may decode the received signal to recover the information packet, and obtain a first probability sequence indicating probability information of each information bit constituting the information packet. The encoder 120 may code the information packet to obtain a code packet, and use the first probability sequence to obtain a second probability sequence representing probability information of each code bit constituting the code packet. Also, the modulator 130 may obtain the modulation symbol using the second probability sequence.

In another example, the decoder 110 of the wireless repeater 100 decodes the received signal into an information packet of information bits, selects at least one suspect bit of the information bits, A first probability sequence indicating probability information on the remaining information bits excluding the bits can be obtained. The encoder 120 may code the information packet to obtain a code packet, and may use the first probability sequence to obtain a second probability sequence representing probability information of each code bit constituting the code packet. Also, the modulator 130 may obtain the modulation symbol using the second probability sequence.

As another example, the decoder 110 of the wireless repeater 100 may decode the received signal into a first information packet of information bits, and invert some or all of the suspect bits of the information bits to generate at least one A second information packet can be generated. The encoder 120 may encode the first information packet and the second information packet to generate a plurality of code packets. The modulator 130 modulates the plurality of code packets to generate a plurality of modulation symbols, and obtains an average of the plurality of modulation symbols.

The present invention may be implemented in hardware, software, or a combination thereof. (DSP), a programmable logic device (PLD), a field programmable gate array (FPGA), a processor, a controller, a microprocessor, and the like, which are designed to perform the above- A processor, another electronic unit, or a combination thereof. In software implementation, it may be implemented as a module that performs the above-described functions. The software may be stored in a memory unit and executed by a processor. The memory unit or processor may employ various means well known to those skilled in the art.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. It will be understood that various modifications and changes may be made without departing from the spirit and scope of the invention. Accordingly, modifications of the embodiments of the present invention will not depart from the scope of the present invention.

1 is a diagram illustrating a relay procedure according to an AF mode.

2 is a diagram illustrating a relay procedure according to the DF mode.

3 is a diagram illustrating a wireless communication system using a repeater.

4 is a flowchart showing an example of a process in which a signal is transmitted from a source station to a target station through a repeater.

5 is a flowchart illustrating an operation method of a repeater according to an embodiment of the present invention.

6 is a diagram showing an example of a convolutional encoder having a rate of 1/2.

7 is a trellis according to the convolutional encoder of FIG.

FIG. 8 shows a constellation diagram of a quadrature phase shift keying (QPSK) modulation scheme and a method of obtaining a modulation symbol according to an embodiment of the present invention.

9 is a flowchart illustrating an operation method of a repeater according to another embodiment of the present invention.

10 is a flowchart illustrating an operation method of a repeater according to another embodiment of the present invention.

11 is a block diagram of a wireless repeater in accordance with an embodiment of the present invention.

Claims (11)

A method of operating a repeater in a wireless communication system, Decoding the received signal to recover the information packet, and obtaining a first probability sequence indicating probability information of each information bit constituting the information packet; Obtaining a code packet by encoding the information packet and obtaining a second probability sequence indicating probability information of each code bit constituting the code packet using the first probability sequence; And And obtaining a modulation symbol using the second probability sequence, The modulation symbol is obtained by using a probability of a constellation point according to a modulation scheme predefined between the relay station and the target station, Wherein the modulation symbol is obtained as a sum of values obtained by multiplying the probabilities of the respective star points and the coordinates of the respective star points. The method according to claim 1, Wherein the second probability sequence is obtained using one of a convolutional coder, a low density parity check (LDPC) coder, and a turbo coder. delete delete The method according to claim 1, Wherein the one station is a modulation symbol when the sum of values obtained by multiplying the probability of each station of the station and the coordinates of each station is less than a predetermined value. A method of operating a repeater in a wireless communication system, Decrypting the received signal to reconstitute the information packet into information packets; Selecting at least one suspicious bit among the information bits; Obtaining a first probability sequence indicating probability information on the remaining information bits except for the suspicious bits and the suspicious bits; Obtaining a code packet by encoding the information packet and obtaining a second probability sequence indicating probability information of each code bit constituting the code packet using the first probability sequence; And And obtaining a modulation symbol using the second probability sequence, The modulation symbol is obtained by using a probability of a constellation point according to a modulation scheme predefined between the relay station and the target station, Wherein the modulation symbol is obtained as a sum of values obtained by multiplying the probabilities of the respective star points and the coordinates of the respective star points. The method according to claim 6, Wherein the suspect bit is a predetermined number of information bits having a difference between a probability of 0 and a probability of one day less than a predetermined value or a difference between a probability of 0 and a probability of one being the smallest. 8. The method of claim 7, Wherein the probability information of the information bit is 0.5, and the probability of 0 is 1 and the probability of being 1 is 0.5, and the probability of 0 and 1 of the remaining information bits excluding the suspect bit is 1, Operating method of the repeater. delete delete A repeater in a wireless communication system, A decoder configured to decode a received signal to reconstruct it as an information packet and to obtain a first probability sequence indicating probability information of each information bit constituting the information packet; An encoder configured to code the information packet to obtain a code packet and to obtain a second probability sequence indicating probability information of each code bit constituting the code packet using the first probability sequence; And And a modulator configured to obtain a modulation symbol using the second probability sequence, The modulation symbol is obtained by using a probability of a constellation point according to a modulation scheme predefined between the relay station and the target station, Wherein the modulation symbol is obtained as a sum of values obtained by multiplying the probability of each sex store and the coordinates of each sex store.

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