A Novel Observe-and-Forward Scheme in Wireless Cooperative Relaying Systems

In this paper, a novel observe-and-forward (OF) cooperative scheme is proposed for relay-enhanced wireless cooperative systems. In this scheme, the codewords transmitted from the source are regenerated by the decoder at the relay and forwarded without re-encoding or interleaving. The decoding processes for different streams of a transmitted codeword can be parallel, which greatly reduces the relaying latency and the complexity of the relay. Furthermore, classical Viterbi algorithm (VA) decoding is adopted at the destination while a Turbo decoding is necessary in decoded-and-forward with coded cooperation (DF-CC) scheme. Union bounds on error performances and the achievable rates are analyzed for the OF scheme. Both the analysis and simulation show that the proposed OF scheme works as well as the classical DF scheme and even better than the DF-CC scheme in some scenarios. The features of the proposed OF scheme are smaller relaying latency and lower complexity, which facilitate the application of this relaying scheme.