Energy-Efficient Medium Access Control in Wireless Sensor Networks

Sensor nodes are standalone devices in wireless sensor networks (WSNs) that draw energy from their batteries to carry out their functions. When a sensor node exhausts its power, it is not able to function anymore. The death of a sensor node can lead to traffic interruption because other nodes may rely on this node to forward their data. Hence, two important things should be considered while designing medium access control (MAC) protocols for WSNs: minimizing unnecessary energy consumption in sensor nodes and distributing load uniformly among them. The proposed model, Energy-Efficient Medium Access Control (EE-MAC), works towards achieving both these things. EE-MAC considers four crucial parameters: threshold energy (TE), proximity threshold (PT), maximum cluster size (MCS), and verification period (VER). The TE value ensures that sensor nodes with low energy levels do not become cluster heads. The PT value prevents cluster heads from lying too close to each other. The MCS value stops clusters from becoming too big. The VER is used to minimize idle listening in cluster heads. EE-MAC is compared with four existing MAC protocols, namely BMA-MAC, LDC-MAC, BEE-MAC, and ES-MAC, in four different scenarios. In scenario 1, 100 sensor nodes are randomly deployed in a 100 x 100 m(2) area in which 10% sensor nodes are cluster heads. In scenario 2, 100 sensor nodes are randomly deployed in a 100 x 100 m(2) area in which 20% sensor nodes are cluster heads. In scenario 3, 200 sensor nodes are randomly deployed in a 100 x 100 m(2) area in which 10% sensor nodes are cluster heads. In scenario 4, 200 sensor nodes are randomly deployed in a 100 x 100 m(2) area in which 20% sensor nodes are cluster heads. When simulating a protocol, the network lifetime is decided by the round number in which the first node dies. During the simulation of EE-MAC in scenario 1, the first node dies in round number 3289. During the simulation of EE-MAC in scenario 2, the first node dies in round number 2539. During the simulation of EE-MAC in scenario 3, the first node dies in round number 2858. During the simulation of EE-MAC in scenario 4, the first node dies in round number 2109. It is observed that EE-MAC outperforms the other protocols in extending the network lifetime in all the scenarios.