Energy Efficient Constellation Size Design for Green Radios in Semi-Blind Relay Networks

Green radios have drawn much attention in recent years. This paper derives the energy per good-bit expressions for semi-blind relay networks with and without maximum ratio combining under Rayleigh fading channels considering the energy consumed per bit as well as the link reliability and retransmission probabilities. The optimal constellation size is investigated constrained by a given bit error rate. The energy consumed in the transmission, reception and idle modes are all involved. Numerical simulations demonstrate the energy efficiency performance of semi-blind relay networks in several cases with the direct transmission as the benchmark. Finally some practical implications can be made from these observations. The analysis and results will be a good reference for the real green cellular communication design.