GHMAC: Green and Hybrid Medium Access Control for Wireless Sensor Networks

A wireless sensor network (WSN) is a resource-constrained network with limited battery, communication range, processing power, bandwidth, etc. and with requirements changing according to the environment and application. The increased number of WSN applications requires efficient utilization of resources in a changing environment to improve the quality of service of the communication. The medium access control (MAC) layer plays a pivotal role in efficient resource utilization for improving channel capacity, delay, energy consumption, and scalability. The contribution of this paper is the improvement of resource utilization by enhancing the MAC in terms of energy efficiency and scalability across different environments including static and mobile scenarios. This is achieved by designing a cluster-based hybrid MAC mechanism, Green Hybrid MAC, which combines the features of both contention- and schedule-based MAC. It uses schedule-based MAC for inter-cluster communication and a mix of schedule- and contention-based MAC for intra-cluster communication according to the level of collisions in the network. The proposed hybrid MAC mechanism uses a three-hop conflict free scheduling algorithm, Green Conflict Free, for finding schedules and uses hybrid synchronization for managing synchronization among the nodes. The proposed hybrid MAC protocol shows significant improvements in energy efficiency, throughput, scalability, and delay in different static, mobile, and security scenarios compared with state-of-art hybrid MAC protocols.