Spectrally Efficient Cooperative Scheme with Implicit Feedback Assisted Transmission

In this paper, an incremental redundancy based cooperative coding scheme for wireless networks is proposed. User cooperation is an effective way of mitigating fading where one user cooperates with another user in transmitting its information, thereby providing spatial diversity. Wireless transmissions are broadcast by nature and this provides a new dimension to the system in terms of an implicit feedback channel from the relay to the source. To exploit the implicit feedback channel a novel incremental redundancy based transmission scheme called incremental code relaying with implicit feedback (ICRIF) is proposed. This scheme enhances the reliability of information transmitted by the relay and thereby improving the throughput at the destination. By employing a powerful code such as low-density parity-check (LDPC) code, the benefit of the proposed scheme is clearly established. The simplified error probability for correct reception of the proposed scheme is derived with respect to direct transmissions and transmissions assisted by the relay.