Minimizing energy consumption in sensor networks using a wakeup radio

For increasing the life of sensor networks, each node must conserve energy as much as possible. In this paper, we propose a protocol in which energy is conserved by amortizing the energy cost of communication over multiple packets. In addition, we allow sensors to control the amount of buffered packets since storage space is limited. To achieve this, a two-radio architecture is used which allows a sensor to "wakeup" a neighbor with a busy tone and send its packets for that destination. However, this process is expensive because all neighbors must awake and listen to the primary channel to determine who is the intended destination. Therefore, triggered wakeups on the primary channel are proposed to avoid using the more costly wakeup procedure. We present a protocol for efficiently determining how large the period for these wakeups should be such that energy consumption is minimized.

I. Introduction

The emergence of sensor networks presents many new challenges in wireless ad hoc networks. While the precise application of sensor networks is speculative, certain characteristics are typically assumed. First, the sensors are static after initial deployment (unless placed on a mobile entity [1]). Second, energy is scarce and it is inconvenient or impossible to replenish the energy source frequently.