Analysis of per-node traffic load in multi-hop wireless sensor networks

The energy expended by sensor nodes in data communication makes up a significant quantum of their total energy consumption. Consequently, a mathematical model that can accurately predict the communication traffic load of a sensor node is critical for designing efficient sensor network protocols. In this paper, we present an analytical model for estimating the per-node traffic load in a multi-hop wireless sensor network. We consider a typical scenario wherein, the sensor nodes periodically sense the environment and forward the collected samples to a sink using greedy geographic routing. The analysis incorporates the idealistic circular coverage radio model as well as a realistic model, log-normal shadowing. Our results confirm that irrespective of the radio model, the traffic load generally increases as a function of the node´s proximity to the sink. However, in the immediate vicinity of the sink, the two radio models yield quite contrasting results. The ideal radio model reveals the existence of a volcano region near the sink, where the traffic load drops significantly. On the contrary, with the log-normal shadowing model, the opposite effect is observed, wherein the traffic load actually increases at a much higher rate as one approaches the sink, resulting in the formation of a mountain peak. The results from our analysis are validated by extensive simulations.