Low power medium access control protocols for wireless sensor networks

Low power medium access control (MAC) protocols have received a lot of attention in the last few years because of their impact on the lifetime of wireless sensor networks. Due to the cost of implementation on real hardware, and sometimes to a lack of detail in the description of these protocols, it is difficult to evaluate them. This paper describes the latest advances in the field and introduces an ideal protocol as a benchmark. It presents detailed analytical models of the power consumption of the best and latest low power MAC protocols. These models are then used to evaluate how the performance of these protocols evolves when modifying traffic rate and network density. It is shown that the most recent scheduled protocols cannot go below the maximal acceptable mean power consumption for battery operated sensor networks. The synchronous random access protocols S-MAC and SCP-MAC scale better, but are outperformed by asynchronous random access protocols based on preamble sensing such as WiseMAC, CSMA-MPS, X-MAC and SyncWUF. These last protocols offer the lowest power consumption for all considered data rates and for all considered network densities.