Trade-offs in energy consumption and throughput for a simple two-relay network

In this paper, we consider a simple two-relay wireless sensor network with packet retransmission where transmission energy and network geometry can be adjusted to improve the energy efficiency of the whole network. We model the energy states of the system as a Markov chain. With both analytical and numerical methods, we investigate how total energy consumption per packet and system throughput are affected by transmit energy allocation and network geometry. The results indicate that the maximum system throughput and minimum system energy consumption per packet can not be optimized simultaneously. We show there are three operating regions representing different throughput and total energy consumption tradeoffs. The approach taken in this paper could be applied to the sensor networks that have no hard requirement on the throughput and delay.