Method for transmitting a digital signal for a semi-orthogonal MARC system having half-duplex relay, and corresponding program product and relay device

A method for transmitting a digital signal intended for a Multiple Access Relay Channel (MARC) system with at least four nodes comprising two senders, a relay and a receiver separated from one another by non-orthogonal links except between the relay and the receiver, between which the link is orthogonal, implementing a spatially distributed network code, the method comprising:

• a step of coding, in each sender, delivering a code word per block of K information bits,
• a step of sending, in the senders, the code word during αN transmission intervals, αε[0,1],
• a step of iterative joint detection/decoding, in the relay, so as to separate interfering streams originating from the senders and determine per stream a vector representative of the K information bits associated with the code word,
• a step of joint coding, in the relay, of the two vectors so as to determine redundancy information, and
• a scheduling in the relay so as to send the redundancy information during the (1−α)N following transmission intervals,
• wherein N denotes the total number of channel uses, and
• wherein the iterative joint detection/decoding step implements a soft decoding and the joint coding step implements a soft coding and a compression.

A non-transitory information medium comprising program instructions stored thereon and adapted to implement a method for transmitting a digital signal when said program is loaded and executed in a semi-orthogonal Multiple Access Relay Channel (MARC) system, wherein the digital signal is transmitted in network with at least four nodes comprising two senders, a relay and a receiver separated from one another by non-orthogonal links except between the relay and the receiver, between which the link is orthogonal, implementing a spatially distributed network code, and wherein the program instructions comprise:

• instructions configured to implement a step of coding, in each sender, delivering a code word per block of K information bits,
• instructions configured to implement a step of sending, in the senders, the code word during αN transmission intervals, αε[0,1],
• instructions configured to implement a step of iterative joint detection/decoding, in the relay, so as to separate interfering streams originating from the senders and determine per stream a vector representative of the K information bits associated with the code word,
• instructions configured to implement a step of joint coding, in the relay, of the two vectors so as to determine redundancy information, and
• instructions configured to implement a step of scheduling in the relay so as to send the redundancy information during the (1−α)N following transmission intervals,
• wherein N denotes the total number of channel uses and
• wherein the iterative joint detection/decoding step implements a soft decoding and the joint coding step implements a soft coding and a marginalization performed at a bit level.

A relay configured for use in a semi-orthogonal Multiple Access Relay Channel (MARC) system for transmitting a digital signal in a network with at least four nodes comprising two senders, the relay and a receiver separated from one another by non-orthogonal links except between the relay and the receiver, between which the link is orthogonal, implementing a spatially distributed network code, the relay comprising:

• means for iterative joint detection/decoding for separating interfering streams originating from the two senders of the semi-orthogonal MARC system, for implementing a soft decoding and for determining, per stream, a vector representative of K information bits associated with a code word sent by a sender during αN transmission intervals, αε[0,1],
• means for joint coding of the vectors of the two streams by implementing a soft coding with a marginalization performed at a bit level and for determining redundancy information,
• means for sending the redundancy information during (1−α)N transmission intervals which follow the αN transmission intervals during which the code words are sent by the two senders,
• wherein N denotes the total number of channel uses.

A method receiving a digital signal by a receiver of a semi-orthogonal Multiple Access Relay Channel (MARC) system in which a digital signal is transmitted in a network with at least four nodes comprising two senders, a relay and the receiver separated from one another by non-orthogonal links except between the relay and the receiver, between which the link is orthogonal, implementing a spatially distributed network code, the method of receiving comprising:

• a step of storage in a block of data received during αN , transmission intervals, αε[0,1 ], corresponding to K information bits coded per sender in the form of a code word sent during the αN transmission intervals, and comprising in an iterative manner:
• the step of detection of compressed soft encoded redundancy information originating from a relay and received during (1−α)N transmission intervals which follow the αN transmission intervals taking into account the equivalent channel resulting from the transmission of the compressed soft encoded redundancy information,
• a detection step of separating interfering streams originating from the senders on the basis of a block of data received, and
• a joint decoding step of determining per sender a decoding value for the K information bits by jointly decoding the separate streams and the detected redundancy information,
• wherein N denotes the total number of channel uses.

A non-transitory information medium comprising program instructions stored thereon and adapted to implement a method for transmitting a digital signal when said program is loaded and executed in a semi-orthogonal Multiple Access Relay Channel (MARC) system, wherein the digital signal is transmitted in network with at least four nodes comprising two senders, a relay and a receiver separated from one another by non-orthogonal links except between the relay and the receiver, between which the link is orthogonal, implementing a spatially distributed network code, and wherein the program instructions comprise:

• instructions configured to implement a step of coding, in each sender, delivering a code word per block of K information bits,
• instructions configured to implement a step of sending, in the senders, the code word during αN transmission intervals, αε[0,1 ],
• instructions configured to implement a step of iterative joint detection/decoding, in the relay, so as to separate interfering streams originating from the senders and determine per stream a vector representative of the K information bits associated with the code word,
• instructions configured to implement a step of joint coding, in the relay, of the two vectors so as to determine redundancy information, and
• instructions configured to implement a step of scheduling in the relay so as to send the redundancy information during the (1−α)N following transmission intervals
• wherein N denotes the total number of channel uses, and
• wherein the iterative joint detection/decoding step implements a soft decoding and the joint coding step implements a soft coding and a compression.

A relay configured for use in a semi-orthogonal Multiple Access Relay Channel (MARC) system for transmitting a digital signal in a network with at least four nodes comprising two senders, the relay and a receiver separated from one another by non-orthogonal links except between the relay and the receiver, between which the link is orthogonal, implementing a spatially distributed network code, the relay comprising:

• means for iterative joint detection/decoding for separating interfering streams originating from the two senders of the semi-orthogonal MARC system by implementing a soft decoding and for determining, per stream, a vector representative of K information bits associated with a code word sent by one of the senders during αN transmission intervals, αε[0,1],
• means for joint coding of the vectors of the two streams by implementing a soft coding and a compression for determining redundancy information, and
• means for sending the redundancy information during (1−α)N transmission intervals which follow the αN transmission intervals during which the code words are sent by the two senders,
• wherein N denotes the total number of channel uses.