This paper proposes an adaptive hierarchical MAC protocol (AH-MAC) with cross-layer optimization for low-rate and large-scale wireless sensor networks. The main goal of the proposed protocol is to combine the strengths of LEACH and IEEE 802.15.4 while offsetting their weaknesses. The predetermined cluster heads are supported with an energy harvesting circuit, while the normal nodes are battery-operated. To prolong the network’s operational lifetime, the proposed protocol transfers most of the network’s activities to the cluster heads while minimizing the node’s activity. Some of the main features of this protocol include energy efficiency, self-configurability, scalability, and self-healing. The simulation results showed great improvement of the AH-MAC over LEACH protocol in terms of energy consumption and throughput. AH-MAC consumes eight times less energy while improving throughput via acknowledgment support.

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This paper investigates many drawbacks and limitations of current clustering algorithms designed for wireless sensor networks. These limitations include high resource requirements, significant overhead, tight synchronization requirements, and TDMA limitations. A new clustering algorithm called hybrid access and an adaptive duty cycle clustering (HADC) protocol is introduced, aiming to address the previous limitations. HADC protocol is based on several concepts, including static clusters, adaptive duty cycling, hybrid scheme channel access, minimum node's functionality, and pseudo synchronization. The resulting network's important features are energy efficiency, robustness, low latency, scalability, and self-healing. The functionality of HADC is validated by both simulation and laboratory experiments. Simulation results show significant improvement of HADC over the well-known LEACH protocol in terms of energy, latency, and packet delivery ratio. The experiment results show that the node's lifetime with two 3000 mAh batteries and transmitting four packets per minute is about 16 years. The lifetime of the cluster head supported by the same energy sources ranges from 110 to 472 days. HADC is the first clustering algorithm designed for sporadic and low rate WSN applications to the best of authors' knowledge.