A multi-node incremental relaying scheme for wireless sensor networks

In wireless sensor networks, multi-node cooperative relaying (MR) scheme represents a potential candidate to combat the effects of channel fading by exploiting diversity gain achieved via cooperation among the relays nodes. But, a great many of relaying channels are employed in MR system, which means that the number of required channels, the energy consumption and transmission delay all increase linearly with the number of relay nodes. In order to minimize energy consumption and improve spectrum efficiency, a multi-node incremental relaying (MIR) scheme is developed and an approach of performance analysis for the MIR system is proposed in this paper. We derived expressions of normalized delay, normalized throughput and energy efficiency for the MIR system respectively. Then, the effects of the number of relay nodes and communication distance on normalized delay, normalized throughput and energy efficiency are discussed in detail for the MIR system. The results indicate that MIR system is more energy efficient than non-cooperative transmission system when the communication distance is above the threshold distance. Moreover, energy efficiency of MIR system can be enhanced through optimizing the number of relay nodes. At last, normalized throughput of MIR system also exceeds that of non-cooperative transmission system for any value of the communication distance.