SLAR: A smart regenerative cooperative protocol with improved power and spectral efficiency

Selective decode and forward (SDF) based cooperative relaying protocol can provide full diversity. But SDF protocol requires bandwidth consuming cyclic redundancy check (CRC) bits to prevent error propagation from the relay. Link adaptive regenerative relaying (LAR) scheme avoids the need for CRC bits to reduce the error propagation from relay and can provide full diversity. But in the conventional LAR based schemes, relay will always participate in the cooperation irrespective of the quality of the source to destination link. This results in a spectral efficiency of 0.5 symbols per channel use (SPCU) only. To improve the transmission rate, the present paper proposes selective link adaptive regenerative relaying (SLAR) scheme, where the relay will make use of the source to destination channel information to decide whether to cooperate or not. It is proved that the proposed scheme can achieve the full diversity order. The spectral efficiency and power efficiency of the protocol are considerably improved compared to the conventional LAR scheme.