Optimization Method of Adaptive Backoff and Duty Cycle for S-MAC Protocol in Wireless Sensor Networks

As a matter of fact that the network traffic has a great influence on the binary exponential backoff mechanism, duty cycle mechanism, and fixed transmission power mechanism adopted by the Sensor Medium Access Control (S-MAC) protocol. The paper proposes an Adaptive Backoff and Duty Cycle for S-MAC protocol (ABDC-SMAC). In the backoff mechanism, considering the failure times of channel competitions, the length of buffer queue, and the node residual energy across the board, a cross-control backoff mechanism is proposed. In the duty cycle mechanism, the network traffic is judged by the average network flow factor. Based on the average network flow factor, the value of duty cycle can change around its initial value. In the power control mechanism, the minimum transmission power can be obtained by the Friis formula. At the same time, the exponential formula following the change of network traffic is selected and multiplied by the minimum transmission formula. The simulation results show that the performance of proposed ABDC-SMAC protocol is improved obviously on energy consumption and transmission delay.