Analyzing MAC Protocols for Low Data-Rate Applications
The fundamental wireless sensors network (WSN) requirement to be energy-efficient has produced a whole range of specialized medium access control (MAC) protocols. They differ in how performance (latency, throughput) is traded off for a reduction in energy consumption. The question "which protocol is best?" is difficult to answer because (i) this depends on specific details of the application requirements and hardware characteristics involved, and (ii) protocols have mainly been assessed individually with each outperforming the canonical S-MAC protocol, but with different simulators, hardware platforms, and workloads. This article addresses that void for low data-rate applications where collisions are of little concern, making an analytical approach tractable in which latency and energy consumption are modeled as functions of key protocol parameters (duty cycle, slot length, number of slots, etc.). By exhaustive search we determine the Pareto-optimal protocol settings for a given workload (data rate, network topology). Of the protocols compared we find that Wise MAC strikes the best latency versus energy-consumption tradeoff across the range of workloads considered. In particular, its random access scheme in combination with local synchronization not only minimizes protocol overhead, but also maximizes the available channel bandwidth.
sensor networks performance energy efficiency performance modeling