VTA-SMAC: Variable Traffic-Adaptive Duty Cycled Sensor MAC Protocol to Enhance Overall QoS of S-MAC Protocol

Sensing and monitoring the physical conditions are basic purposes of Wireless Sensor Networks (WSN). Sensor nodes are the building blocks of WSN and they are battery operated. Battery charging or changing is impossible in harsh areas of deployment, so battery life needs to be maximized by improving the MAC protocol. If the Duty Cycle is selected wisely, it may reduce energy utilizations of a wireless sensor network, but it may impact other factors of WSN as well. Optimum duty cycle for a specific data traffic may not be optimal for other levels of data traffic and it may negatively affect the performance of a wireless sensor network. An adaptive duty cycle algorithm, VTA-SMAC (Variable Traffic-Adaptive Duty Cycle Sensor MAC) is proposed to reduce the problem of idle listening or collisions and to reduce energy consumption of traditional S-MAC protocol. VTA-SMAC algorithm was simulated in Network Simulator NS-2 and simulation results were evaluated to assess the impact of duty cycle variation on performance of S-MAC, particularly energy conservation with condition of varying data traffic. Impact of duty cycle variation in accordance with data traffic were also evaluated on various factors like latency, throughput, collisions, delay, jitter, and packet delivery ratio etc. Trade-off between energy consumption and latency was also studied. Simulation results show that VTA-SMAC improves energy conservation by 19.9 %, 14.4 % and 20.2 % at low, medium, and high traffic, respectively. Latency is also decreased by 10.2 %, 7.5 % and 18.9 % at low, medium, and high traffic, respectively.