Realizing Wireless Cooperative Communications with the One-Bit Soft Forwarding Technique

To improve the efficiency and simplify the complexity of the relay in cooperative communication systems, an one-bit soft forwarding (SF) scheme is proposed to exploit the erroneously decoded packets that are normally abandoned by the selection decode-and-forward (DF) scheme at the relay, as side information to assist decoding of the direct-link packet at the basestation. As this side information from relay is encoded and transmitted in the same format as the usual data packet, the proposed SF scheme can be implemented with the same coding scheme and same encoder/decoder as the DF scheme. It only requires the additional transmission of a packet reliability value from the relay to the basestation, unlike the previous soft relaying schemes which require more complicated soft output decoding and signaling format. The new scheme not only allows low complexity implementation, but also offers considerable error performance gain. Simulation results demonstrate that our SIT scheme outperforms the selection DF by up to 2 dB, especially when the inter-link channel is poor.