JP6382040B2 - COMMUNICATION SYSTEM, RELAY DEVICE, RECEPTION DEVICE, RELAY METHOD, RECEPTION METHOD, RELAY PROGRAM, AND RECEPTION PROGRAM - Google Patents

Description

  The present invention relates to a communication system, a relay device, a reception device, a relay method, a reception method, a relay program, and a reception program that improve communication quality by relaying a signal from a transmission device.

In this specification, the transmission device, the relay device, and the reception device may be referred to as a transmission node, a relay node, and a reception node, respectively.
In a communication system, particularly a wireless communication system, a communication system that improves communication quality using a plurality of relay nodes existing between a transmission node and a reception node has been studied (for example, see Non-Patent Document 1). . FIG. 1 is a diagram illustrating a configuration of a communication system using a plurality of relay nodes. Here, the number of relay nodes 200 in the communication system may be an arbitrary number of 1 or more. The connection between the transmission node 100 and the relay node 200 and between the relay node 200 and the reception node 300 may be either a wired connection or a wireless connection.

  Some communication systems quantize the likelihood detected at the relay node during communication between the transmission node and the relay node and transfer it to the reception node. In addition, detection is performed to reduce the likelihood quantization bits. A relay system that adaptively changes the quantization parameter in accordance with the probability distribution of the likelihood has been studied (for example, see Non-Patent Document 2).

  On the other hand, in a wireless communication system, particularly a mobile communication system, a configuration in which a plurality of antenna units equipped with a part of a base station function are physically extended and used as a distributed station is being studied. Here, the antenna unit is a unit on which a transmission interface, a radio transceiver, and an antenna are mounted. The base station that overhangs the distributed station has a function of controlling a plurality of distributed stations as a central station.

  FIG. 2 is a diagram illustrating a configuration of a communication system using likelihood adaptive quantization when a relay node and a reception node are connected by wire. In this case, the transmitting node 100, the relay node 200, and the receiving node 300 can also be regarded as terminals, distributed stations, and central stations in a mobile communication system in which the base station functions described above are divided into a central station and a distributed station, respectively.

  First, a signal transmitted from the transmission node 100 is received by the radio reception unit 21 of the relay node 200, and noise is added. The soft demodulator 22 of each relay node detects the likelihood of the received signal by performing soft demodulation on the received signal. Next, the quantization parameter calculation unit 23 calculates a quantization parameter (what quantization width is adopted) by observing the probability distribution of the detected likelihood, and the likelihood adaptive quantization unit 24 The likelihood adaptive quantization is performed according to the quantization parameter. The quantization parameter includes, for example, a quantization level value that is a value after quantization.

  The quantized likelihood is transmitted from the wired transmission unit 25 of each relay node to the reception node 300 as a likelihood quantization bit value represented by bits “0” and “1”. Here, since the receiving node 300 is not sure what quantization parameter is used for the transmitted likelihood, the relay node 200 uses the quantization parameter together with the likelihood quantization bit value. To the receiving node 300. Finally, the inverse quantization unit 32 of the reception node 300 performs the inverse quantization process based on the notified quantization parameter, determines the received bit, and transfers the signal to the upper layer function 33.

  FIG. 3 is a diagram for explaining the configuration of a communication system using likelihood adaptive quantization when the relay node 200 and the receiving node 300 are wirelessly connected. In this case, the processing up to the likelihood-applied quantization in the relay node 200 is the same as in the configuration of FIG. 2, but the likelihood quantized bit value is modulated by the radio transmission unit 26 and received as a radio signal. It is transmitted to the node 300. In the reception node 300, the signal from each relay node 200 is received by each radio reception unit 34, demodulated by the demodulation unit 35, and the process of inverse quantization is performed. At this time, the demodulation process may be either hard decision or soft decision.

  The communication system shown in FIG. 2 and FIG. 3 can improve the communication quality as compared with the direct communication between the transmission node and the reception node.

Shinsuke Costume, Seiichi Sampei, IEICE Technical Report, vol. 113, no. 456, RCS2013-336, 181-186, “A Study on Optimization of Quantization Threshold in Regenerative Quantum Relay Transmission”, March 2014. Clemens Novak, et al. , Proc. ISIT 2009, pp. 1070-1074, “Quantification for Soft-Output Demodulators in Bit-Interleaved Coded Modulation Systems” July, 2009.

  However, in the configurations of FIGS. 2 and 3, the number of bits required when notifying the quantization parameter that changes depending on the reception quality increases, and an increase in overhead between the relay node and the reception node becomes a problem. For example, when the likelihood is quantized with 3 bits, it is necessary to notify the reception node of the 8-level quantization level value (quantization parameter) every time the reception quality changes. In order to represent each quantization level value, it is necessary to use a numerical expression such as a floating-point number. For example, when a double-precision floating-point number is used, a 64-bit bit per quantization level value is used. A number is needed. In other words, the relay node must notify the receiving node of the quantization parameter (quantization level value for each stage) that is applied to the current signal. In the above example, the number of bits is 8 stages × 64 bits = 512 bits. Necessary for one-time quantization parameter notification.

  In the present invention, in order to solve such a problem, the number of bits required for notification of the quantization parameter is reduced when the likelihood detected by the relay device in the signal from the transmission device is quantized and transmitted to the reception device. It is an object of the present invention to provide a communication system, a relay device, a reception device, a relay method, a reception method, a relay program, and a reception program that can reduce transmission overhead.

  In order to achieve the above object, in the present invention, the probability distribution of likelihood and the optimal quantization parameter are determined from the modulation scheme and the received SNR (Signal to Noise Ratio) in the communication system used between the transmission node and the relay node. Use what can be calculated in advance. In the reception SNR in the range where the probability distribution of the likelihood can be considered to be the same for each modulation scheme, the optimal quantization parameter is calculated in advance and provided as a quantization code book at the relay node and the reception node. By notifying the receiving node of only the codebook number indicating the SNR range, overhead between the relay node and the receiving node is reduced.

Specifically, a communication system according to the present invention includes a transmission device that transmits a signal, a reception device that receives the signal, a relay device that relays the signal between the transmission device and the reception device, A communication system comprising:
The relay device is
A first signal receiving unit for receiving a signal from the transmitting device side;
A reception SNR (Signal to Noise Ratio) value is estimated from the signal power and noise power of the signal received by the first signal reception unit, and a codebook number indicating a corresponding reception SNR range is selected from the reception SNR value. An SNR estimator;
A soft demodulation unit that performs soft demodulation on the signal received by the first signal reception unit and detects the likelihood of the signal;
A first quantization codebook describing a relationship between a quantization parameter for quantizing the likelihood and a likelihood quantization bit value obtained by quantizing the likelihood for each codebook;
A likelihood adaptation that refers to the first quantization codebook and adaptively quantizes the likelihood detected by the soft demodulation unit based on a quantization parameter corresponding to the codebook number selected by the received SNR estimation unit A quantization unit;
A transmission unit that outputs a signal including a likelihood quantization bit value obtained by quantizing the likelihood by the likelihood adaptive quantization unit and the codebook number selected by the reception SNR estimation unit to the reception device side;
Have
The receiving device is:
A second signal receiving unit for receiving a signal from the relay device;
A second quantization codebook having the same content as the first quantization codebook of the relay device;
With reference to the second quantization code book, the relationship between the quantization parameter corresponding to the code book number included in the signal received by the second signal receiving unit and the likelihood quantization bit value is used. An inverse quantization unit that performs an inverse quantization process on the quantized likelihood included in the signal received by the two-signal reception unit;
It is characterized by having.

A relay device according to the present invention is a relay device that relays the signal between a transmission device that transmits a signal and a reception device that receives the signal,
A first signal receiving unit for receiving a signal from the transmitting device side;
A reception SNR (Signal to Noise Ratio) value is estimated from the signal power and noise power of the signal received by the first signal reception unit, and a codebook number indicating a corresponding reception SNR range is selected from the reception SNR value. An SNR estimator;
A soft demodulation unit that performs soft demodulation on the signal received by the first signal reception unit and detects the likelihood of the signal;
A first quantization codebook describing a relationship between a quantization parameter for quantizing the likelihood and a likelihood quantization bit value obtained by quantizing the likelihood for each codebook;
A likelihood adaptation that refers to the first quantization codebook and adaptively quantizes the likelihood detected by the soft demodulation unit based on a quantization parameter corresponding to the codebook number selected by the received SNR estimation unit A quantization unit;
A transmission unit that outputs a signal including a likelihood quantization bit value obtained by quantizing the likelihood by the likelihood adaptive quantization unit and the codebook number selected by the reception SNR estimation unit to the reception device side;
It is characterized by having.

A receiving apparatus according to the present invention is a receiving apparatus that receives a signal transmitted from a transmitting apparatus and relayed by the relay apparatus according to claim 2,
A second signal receiving unit for receiving a signal from the relay device;
A second quantization codebook having the same content as the first quantization codebook of the relay device;
With reference to the second quantization code book, the relationship between the quantization parameter corresponding to the code book number included in the signal received by the second signal receiving unit and the likelihood quantization bit value is used. An inverse quantization unit that performs an inverse quantization process on the quantized likelihood included in the signal received by the two-signal reception unit;
It is characterized by having.

A relay method according to the present invention is a relay method for relaying the signal between a transmitting device that transmits a signal and a receiving device that receives the signal,
A first signal receiving procedure for receiving a signal from the transmitter side;
A reception SNR (Signal to Noise Ratio) value is estimated from the signal power and noise power of the signal received in the first signal reception procedure, and a codebook number indicating a corresponding reception SNR range is selected from the reception SNR value. An SNR estimation procedure;
Performing a soft demodulation on the signal received in the first signal reception procedure, and detecting a likelihood of the signal;
The relationship between the quantization parameter for quantizing the likelihood and the likelihood quantization bit value for which the likelihood is quantized is referred to the first quantization code book described for each code book, and selected by the received SNR estimation procedure. A likelihood adaptive quantization procedure for adaptively quantizing the likelihood detected in the soft demodulation procedure based on a quantization parameter corresponding to the codebook number;
A transmission procedure for outputting a signal including a likelihood quantized bit value obtained by quantizing the likelihood in the likelihood adaptive quantization procedure and the codebook number selected in the received SNR estimation procedure to the receiving device side;
It is characterized by performing.

A reception method according to the present invention is a reception method in which a signal transmitted from a transmission device and relayed by the relay method according to claim 4 is received by the reception device,
A second signal receiving procedure for receiving a signal relayed by the relay method;
A quantization parameter corresponding to the codebook number included in the signal received in the second signal reception procedure with reference to the second quantization codebook having the same content as the first quantization codebook used in the relay method Using the relationship between the likelihood quantization bit value and the likelihood quantization bit value, an inverse quantization procedure for performing inverse quantization processing on the quantized likelihood included in the signal received in the second signal reception procedure;
It is characterized by performing.

A relay program according to the present invention is a relay program that causes a computer to relay the signal between a transmitting device that transmits a signal and a receiving device that receives the signal,
A first signal receiving procedure for receiving a signal from the transmitter side;
A reception SNR (Signal to Noise Ratio) value is estimated from the signal power and noise power of the signal received in the first signal reception procedure, and a codebook number indicating a corresponding reception SNR range is selected from the reception SNR value. An SNR estimation procedure;
Performing a soft demodulation on the signal received in the first signal reception procedure, and detecting a likelihood of the signal;
The relationship between the quantization parameter for quantizing the likelihood and the likelihood quantization bit value for which the likelihood is quantized is referred to the first quantization code book described for each code book, and selected by the received SNR estimation procedure. A likelihood adaptive quantization procedure for adaptively quantizing the likelihood detected in the soft demodulation procedure based on a quantization parameter corresponding to the codebook number;
A transmission procedure for outputting a signal including a likelihood quantized bit value obtained by quantizing the likelihood in the likelihood adaptive quantization procedure and the codebook number selected in the received SNR estimation procedure to the receiving device side;
Is executed by a computer.

A reception program according to the present invention is a reception program that causes a computer to receive a signal transmitted from a transmission device and relayed by the relay device according to claim 2,
A second signal receiving procedure for receiving a signal from the relay device;
A quantization parameter corresponding to the codebook number included in the signal received in the second signal reception procedure with reference to a second quantization codebook having the same content as the first quantization codebook of the relay device; Using a relationship with the likelihood quantization bit value, an inverse quantization procedure for performing an inverse quantization process on the quantized likelihood included in the signal received in the second signal reception procedure;
Is executed by a computer.

  The present invention is a communication capable of reducing the number of bits required for notification of quantization parameters and reducing transmission overhead when quantizing the likelihood detected by a relay device for a signal from a transmission device and transmitting the quantized signal to the reception device. A system, a relay device, a reception device, a relay method, a reception method, a relay program, and a reception program can be provided.

It is a figure explaining the structure of the communication system using a some relay node. It is a figure explaining the structure of the communication system using likelihood adaptive quantization in case a relay node and receiving nodes are wire connection. It is a figure explaining the structure of the communication system using likelihood adaptive quantization in case a relay node and receiving nodes are wireless connection. It is a figure explaining an example of the quantization code book used with the communication system concerning the present invention. It is a figure explaining the structure of the communication system which concerns on this invention. It is a figure explaining the structure of the communication system which concerns on this invention. It is a figure explaining the structure of the communication system which concerns on this invention. It is a figure explaining the structure of the communication system which concerns on this invention.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are embodiments of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

  In the present invention, the optimal quantization parameter is calculated in advance in the reception SNR in the range where the probability distribution of likelihood can be regarded as the same for each modulation method, and is provided as a quantization codebook at the relay node and the reception node. The relay node notifies only the codebook number indicating the range of the received SNR to the receiving node. For example, when there are two types of modulation schemes and two stages of reception SNR ranges, a total of four types of quantization parameters are prepared. The number of bits of the code book number necessary for the notification of the quantization parameter is 2 bits that can represent four bit sequences. FIG. 4 is an example of the quantization code book of the above example in which the number of likelihood quantization bits is two.

Example 1
FIG. 5 is a diagram illustrating the configuration of the communication system according to the first embodiment. The communication system according to the present embodiment includes a transmission device 100 that transmits a signal, a reception device 301 that receives the signal, and a relay device 201 that relays the signal between the transmission device 100 and the reception device 301. .

The relay apparatus 201 is a relay apparatus that relays the signal between the transmission apparatus 100 that transmits a signal and the reception apparatus 301 that receives the signal.
A first signal receiver (radio receiver 21) that receives a signal from the transmitter 100;
A reception SNR estimation unit 27 that estimates a reception SNR value from the signal power and noise power of the signal received by the first signal reception unit, and selects a codebook number indicating a corresponding reception SNR range from the reception SNR value;
A soft demodulator 22 that performs soft demodulation on the signal received by the first signal receiver and detects the likelihood of the signal;
A first quantization codebook 28 describing a relationship between a quantization parameter for quantizing the likelihood and a likelihood quantization bit value obtained by quantizing the likelihood for each codebook;
A likelihood adaptive quantization that refers to the first quantization codebook 28 and adaptively quantizes the likelihood detected by the soft demodulation unit 22 based on the quantization parameter corresponding to the codebook number selected by the reception SNR estimation unit 27 Part 24;
A transmission unit (wired transmission unit 25) that outputs a signal including the likelihood quantization bit value quantized by the likelihood adaptive quantization unit 24 and the code book number selected by the reception SNR estimation unit 27 to the reception device 301. When,
Have

The relay device 201 can be realized by causing a computer to read a relay program. The relay program is
A first signal reception procedure for receiving a signal from the transmitter side;
A reception SNR estimation procedure for estimating a reception SNR value from the signal power and noise power of the signal received in the first signal reception procedure, and selecting a codebook number indicating a corresponding reception SNR range from the reception SNR value;
Performing a soft demodulation on the signal received in the first signal reception procedure, and detecting a likelihood of the signal;
The relationship between the quantization parameter for quantizing the likelihood and the likelihood quantization bit value for which the likelihood is quantized is referred to the first quantization code book described for each code book, and selected by the received SNR estimation procedure. A likelihood adaptive quantization procedure for adaptively quantizing the likelihood detected in the soft demodulation procedure based on a quantization parameter corresponding to the codebook number;
A transmission procedure for outputting a signal including a likelihood quantized bit value obtained by quantizing the likelihood in the likelihood adaptive quantization procedure and the codebook number selected in the received SNR estimation procedure to the receiving device side;
Can be executed by a computer.

The receiving device 301 is a receiving device that receives a signal transmitted from the transmitting device 100 and relayed by the relay device 201, and
A second signal receiving unit (wired receiving unit 31) that receives a signal from the relay device 201;
A second quantization code book 38 having the same contents as the first quantization code book 28 of the relay apparatus 201;
Referring to the second quantization code book 38, the second signal reception is performed using the relationship between the quantization parameter corresponding to the code book number included in the signal received by the second signal receiving unit and the likelihood quantization bit value. An inverse quantization unit 32 that performs an inverse quantization process on the quantized likelihood included in the signal received by the unit;
Have

The reception device 301 can be realized by causing a computer to read a reception program. The receiving program is
A second signal reception procedure for receiving a signal from the relay device 201;
Referring to the second quantization code book 38 having the same content as the first quantization code book 28 included in the relay apparatus 201, the quantization parameter corresponding to the code book number included in the signal received in the second signal reception procedure Using the relationship between the likelihood quantization bit value and the likelihood quantization bit value, an inverse quantization procedure for performing inverse quantization processing on the quantized likelihood included in the signal received in the second signal reception procedure;
Can be executed by a computer.

  In this embodiment, instead of the quantization parameter calculation performed by the quantization parameter calculation unit 23 of the relay node 200 of FIGS. 2 and 3, the reception SNR estimation unit 27 of each relay node 201 receives the received SNR based on the received signal. Make an estimate. The reception SNR estimation can be estimated by first estimating the reception power and noise power, then subtracting the noise power from the reception power, calculating the reception signal power, and calculating the ratio of the reception signal power and the noise power. The noise power can be estimated by providing a no-signal section in the transmission signal.

  The reception SNR estimation unit 27 selects a codebook number indicating a corresponding reception SNR range from the estimated reception SNR, and notifies the likelihood adaptive quantization unit 24 of the codebook number. It is assumed that the code book number is set in the reception SNR estimation unit 27 in advance.

  The likelihood adaptive quantization unit 24 reads a quantization parameter corresponding to the notified codebook number by referring to the quantization codebook 28 in which a plurality of patterns of quantization parameters are stored, and uses the quantization parameter. The likelihood is quantized to obtain a likelihood quantized bit value. Then, the transmission unit (wired transmission unit 25) of each relay node 201 transmits the likelihood quantization bit value and the codebook number notified from the reception SNR estimation unit 27 to the reception node 301.

  The inverse quantization unit 32 of the reception node 301 refers to the quantization code book 38 based on the notified code book number, reads the quantization parameter of the quantization performed in the relay node 201, and Inverse quantization processing is performed on the received likelihood quantization bit value.

  The transmission node 100 and the relay node 201 may be wired. The signal transmitted / received between the nodes may be either a single carrier signal or a multicarrier signal. Further, the decoding process may be performed after the soft demodulation process in the relay node.

(Example 2)
In the second embodiment, the relay node and the receiving node are wirelessly connected when the method of the first embodiment is used. FIG. 6 is a diagram illustrating the configuration of the communication system according to the second embodiment. In this embodiment, the transmission unit of the relay device 202 is the wireless transmission unit 26, and the second signal reception unit of the reception device 302 is the wireless reception unit 34. Also in this embodiment, the processing until the likelihood quantization bit value and the code book number are acquired is the same as that in the first embodiment. In the present embodiment, the wireless transmission unit 26 corresponding to the transmission unit modulates a signal including the likelihood quantization bit value and the codebook number, and transmits the modulated signal to the reception node 302 as a wireless signal. At this time, MIMO (Multiple-Input Multiple-Output) transmission may be performed in the wireless transmission between each relay node 202 and the receiving node 302. The reception node 302 demodulates the signal from each relay node 202 received by each wireless reception unit 34 by the demodulation unit 35. The inverse quantization unit 32 performs inverse quantization processing in the same manner as in the first embodiment. At this time, the demodulation process may be either hard decision or soft decision. In the case of MIMO transmission, the MIMO processing unit 36 performs MIMO processing before demodulation processing.

  The transmission node 100 and the relay node 202 may be wired. The signal transmitted / received between the nodes may be either a single carrier signal or a multicarrier signal. In addition, encoding processing may be performed before modulation in the radio transmission unit of each relay node, and decoding processing may be performed after demodulation of the relay node or reception node.

(Example 3)
In the third embodiment, when the method of the first embodiment is used, the number of transmitting nodes and the number of relay nodes are arbitrarily set, or the number of antennas of each transmitting node and the number of antennas of each relay node are arbitrarily set in the wireless connection section. It is a number. FIG. 7 is a diagram illustrating the configuration of the communication system according to the third embodiment. Here, the number of transmission nodes 100 is M, and the number of relay nodes 203 is N. In this case, you may perform the MIMO transmission which transmits a single or several data stream in a radio | wireless area. In that case, each relay node 203 further includes a MIMO processing unit 29.

  The relay node 203 estimates the received SNR for the signal after the MIMO processing. After that, the relay node 203 performs soft demodulation and likelihood adaptive quantization as described in the first embodiment for each data stream, and receives and converts the likelihood quantized bit value by parallel-serial conversion by the parallel-serial conversion unit 29a. Transmit to node 303.

  The receiving node 303 performs serial / parallel conversion on the likelihood quantized bit value and the codebook number transmitted from each relay node 203 by the serial / parallel conversion unit 39a, and based on them, the inverse quantum as described in the first embodiment is performed. The bit is determined for each data stream and transferred to the upper layer function.

  The transmission node 100 and the relay node 203 may be wired. The signal transmitted / received between the nodes may be either a single carrier signal or a multicarrier signal. Further, the decoding process may be performed after the soft demodulation process in the relay node.

Example 4
In the fourth embodiment, when the method of the second embodiment is used, the number of transmitting nodes and the number of relay nodes are arbitrarily set, or the number of antennas of each transmitting node and the number of antennas of each relay node are arbitrarily set in the wireless connection section. It is a number. FIG. 8 is a diagram illustrating the configuration of the communication system according to the fourth embodiment. Here, the number of transmission nodes 100 is M, and the number of relay nodes 204 is N. In this case, you may perform the MIMO transmission which transmits a single or several data stream in a radio | wireless area. In that case, each relay node 204 further includes a MIMO processing unit 29.

  The relay node 204 estimates the received SNR for the signal after the MIMO processing. Thereafter, the relay node 204 performs soft demodulation and likelihood adaptive quantization as described in the second embodiment for each data stream, and transmits the result to the reception node 304.

  As described in the second embodiment, the reception node 304 demodulates the signal from each relay node received by each wireless reception unit 34 and performs the inverse quantization process. At this time, the demodulation process may be either hard decision or soft decision.

  The transmission node 100 and the relay node 204 may be wired. The signal transmitted / received between the nodes may be either a single carrier signal or a multicarrier signal. In addition, encoding processing may be performed before modulation in the radio transmission unit of each relay node, and decoding processing may be performed after demodulation of the relay node or reception node.

(Effect of the invention)
In a communication system in which the quantized likelihood parameter is adaptively changed and the quantized likelihood is transmitted from the relay node to the receiving node, the quantization parameter requiring many bits for one notification Instead, by transmitting only the codebook number indicating the reception SNR range from the relay node to the reception node, overhead in transmission between the relay node and the reception node can be reduced.

21: Radio receiver 22: Soft demodulator 23: Quantization parameter calculator 24: Likelihood adaptive quantizer 25: Wired transmitter 26: Radio transmitter 27: Received SNR estimator 28: Quantization codebook 29: MIMO Processing unit 29a: Parallel serial conversion unit 31: Wired reception unit 32: Inverse quantization unit 33: Upper layer function 34: Radio reception unit 35: Demodulation unit 36: MIMO processing unit 38: Quantization codebook 39a: Serial parallel conversion unit 100: Transmission device (transmission node)
200 to 204: Relay device (relay node)
300 to 304: receiving device (receiving node)

Claims (7)

A communication system comprising: a transmission device that transmits a signal; a reception device that receives the signal; and a relay device that relays the signal between the transmission device and the reception device,
The relay device is
A first signal receiving unit for receiving a signal from the transmitting device side;
A codebook number representing a reception SNR (Signal to Noise Ratio) value within a range in which the probability distribution of likelihood is considered to be the same for each modulation scheme of the signal received by the first signal reception unit, and an optimum quantum for each reception SNR A first quantization codebook composed of likelihood quantization bit values obtained by calculating and expressing quantization parameters in advance;
Reception of selecting co Dobukku number the first signal receiving unit estimates the received SNR value from the signal power and the noise power of the received signal, corresponding from the first quantization codebook based on the received SNR value estimated An SNR estimator;
A soft demodulation unit that performs soft demodulation on the signal received by the first signal reception unit and detects the likelihood of the signal ;
A likelihood adaptation that refers to the first quantization codebook and adaptively quantizes the likelihood detected by the soft demodulation unit based on a quantization parameter corresponding to the codebook number selected by the received SNR estimation unit A quantization unit;
The likelihood adaptive quantization unit outputs a signal including the likelihood quantization bit value representing the quantization parameter obtained by quantizing the likelihood and the codebook number selected by the reception SNR estimation unit to the receiving device side A transmission unit to
Have
The receiving device is:
A second signal receiving unit for receiving a signal from the relay device;
A second quantization codebook having the same content as the first quantization codebook of the relay device;
The second quantization code book is referred to, and the second parameter receiving unit uses the quantization parameter represented by the code book number and likelihood quantization bit value included in the signal received by the second signal receiving unit, An inverse quantization unit that performs an inverse quantization process on the quantized likelihood included in the signal received by the signal reception unit;
A communication system comprising: A relay device that relays the signal between a transmission device that transmits a signal and a reception device that receives the signal,
A first signal receiving unit for receiving a signal from the transmitting device side;
A codebook number representing a reception SNR (Signal to Noise Ratio) value within a range in which the probability distribution of likelihood is considered to be the same for each modulation scheme of the signal received by the first signal reception unit, and an optimum quantum for each reception SNR A first quantization codebook composed of likelihood quantization bit values obtained by calculating and expressing quantization parameters in advance;
Reception of selecting co Dobukku number the first signal receiving unit estimates the received SNR value from the signal power and the noise power of the received signal, corresponding from the first quantization codebook based on the received SNR value estimated An SNR estimator;
A soft demodulation unit that performs soft demodulation on the signal received by the first signal reception unit and detects the likelihood of the signal ;
A likelihood adaptation that refers to the first quantization codebook and adaptively quantizes the likelihood detected by the soft demodulation unit based on a quantization parameter corresponding to the codebook number selected by the received SNR estimation unit A quantization unit;
The likelihood adaptive quantization unit outputs a signal including the likelihood quantization bit value representing the quantization parameter obtained by quantizing the likelihood and the codebook number selected by the reception SNR estimation unit to the receiving device side A transmission unit to
A relay apparatus comprising: A receiving device that receives a signal transmitted from a transmitting device and relayed by the relay device according to claim 2,
A second signal receiving unit for receiving a signal from the relay device;
A second quantization codebook having the same content as the first quantization codebook of the relay device;
The second quantization code book is referred to, and the second parameter receiving unit uses the quantization parameter represented by the code book number and likelihood quantization bit value included in the signal received by the second signal receiving unit, An inverse quantization unit that performs an inverse quantization process on the quantized likelihood included in the signal received by the signal reception unit;
A receiving apparatus comprising: A relay method for relaying the signal between a transmitting device that transmits a signal and a receiving device that receives the signal,
A first signal receiving procedure for receiving a signal from the transmitter side;
A signal SNR (Signal to Noise Ratio) value is estimated from the signal power and noise power of the signal received in the first signal reception procedure, and the likelihood probability for each modulation scheme of the signal received in the first signal reception procedure A first quantization code composed of a codebook number representing a received SNR value in a range in which the distribution can be regarded as the same, and a likelihood quantized bit value obtained by calculating an optimal quantization parameter for each received SNR in advance. A received SNR estimation procedure for selecting a codebook number from the book based on the estimated received SNR value;
Performing a soft demodulation on the signal received in the first signal reception procedure, and detecting a likelihood of the signal;
A likelihood adaptation that refers to the first quantization codebook and adaptively quantizes the likelihood detected in the soft demodulation procedure based on a quantization parameter corresponding to the codebook number selected in the received SNR estimation procedure The quantization procedure;
A signal including the likelihood quantization bit value representing the quantization parameter obtained by quantizing the likelihood in the likelihood adaptive quantization procedure and the codebook number selected in the reception SNR estimation procedure is output to the receiving device side Transmission procedure to
The relay method characterized by performing. A reception method in which a signal transmitted from a transmission device and relayed by the relay method according to claim 4 is received by a reception device,
A second signal receiving procedure for receiving a signal relayed by the relay method;
The codebook number and likelihood quantization bit included in the signal received in the second signal reception procedure with reference to the second quantization codebook having the same content as the first quantization codebook used in the relay method An inverse quantization procedure for performing an inverse quantization process on the quantized likelihood included in the signal received in the second signal reception procedure using a quantization parameter represented by a value;
A receiving method characterized by: A relay program for causing a computer to relay the signal between a transmitting device that transmits a signal and a receiving device that receives the signal,
A first signal receiving procedure for receiving a signal from the transmitter side;
A signal SNR (Signal to Noise Ratio) value is estimated from the signal power and noise power of the signal received in the first signal reception procedure, and the likelihood probability for each modulation scheme of the signal received in the first signal reception procedure A first quantization code composed of a codebook number representing a received SNR value in a range in which the distribution can be regarded as the same, and a likelihood quantized bit value obtained by calculating an optimal quantization parameter for each received SNR in advance. A received SNR estimation procedure for selecting a codebook number from the book based on the estimated received SNR value;
Performing a soft demodulation on the signal received in the first signal reception procedure, and detecting a likelihood of the signal;
A likelihood adaptation that refers to the first quantization codebook and adaptively quantizes the likelihood detected in the soft demodulation procedure based on a quantization parameter corresponding to the codebook number selected in the received SNR estimation procedure The quantization procedure;
A signal including the likelihood quantization bit value representing the quantization parameter obtained by quantizing the likelihood in the likelihood adaptive quantization procedure and the codebook number selected in the reception SNR estimation procedure is output to the receiving device side Transmission procedure to
A relay program that causes a computer to execute. A reception program for causing a computer to receive a signal transmitted from a transmission device and relayed by the relay device according to claim 2,
A second signal receiving procedure for receiving a signal from the relay device;
The codebook number and likelihood quantization bit value included in the signal received by the second signal reception procedure with reference to the second quantization codebook having the same content as the first quantization codebook of the relay device An inverse quantization procedure for performing inverse quantization on the quantized likelihood included in the signal received in the second signal reception procedure using the quantization parameter represented by :
A receiving program for causing a computer to execute.

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