An adaptive energy-efficient MAC protocol for wireless sensor networks

TLDR

Applications for wireless sensor networks have low message rates and are insensitive to latency, enabling energy savings through active‑sleep duty cycles. The paper introduces T‑MAC, a contention‑based Medium Access Control protocol for wireless sensor networks. T‑MAC adapts its duty cycle by dynamically ending the active period to handle load variations in time and location. T‑MAC reduces idle‑listening energy while preserving throughput, achieving up to 98 % savings versus CSMA and outperforming S‑MAC by a factor of five under variable load, as shown by extensive simulations and preliminary measurements.

Abstract

In this paper we describe T-MAC, a contention-based Medium Access Control protocol for wireless sensor networks. Applications for these networks have some characteristics (low message rate, insensitivity to latency) that can be exploited to reduce energy consumption by introducing an activesleep duty cycle. To handle load variations in time and location T-MAC introduces an adaptive duty cycle in a novel way: by dynamically ending the active part of it. This reduces the amount of energy wasted on idle listening, in which nodes wait for potentially incoming messages, while still maintaining a reasonable throughput.We discuss the design of T-MAC, and provide a head-to-head comparison with classic CSMA (no duty cycle) and S-MAC (fixed duty cycle) through extensive simulations. Under homogeneous load, T-MAC and S-MAC achieve similar reductions in energy consumption (up to 98%) compared to CSMA. In a sample scenario with variable load, however, T-MAC outperforms S-MAC by a factor of 5. Preliminary energy-consumption measurements provide insight into the internal workings of the T-MAC protocol.