Sigmoid Function-Based Energy Optimization Strategy for Multihop Routing in WSNs

Energy consumption of the wireless sensor network depends on various factors of network such as transmission distance, control signal overhead, duty cycling, and sensing of the signal. Among these factors, duty cycle and transmission distance are the most important factors. Designing of energy optimization strategy for multihop wireless sensor network becomes more challenging due to: (1) routing problem for multihop transmission, (2) residual energy of intermediate nodes for relaying, and (3) network energy utilization during transmission. The strategy proposed in this paper works in dual mode for energy minimization: intra-cluster energy minimization and inter-cluster energy minimization. Since for the transmission of a packet in intra-cluster energy minimization, longer distance node consumes more energy than the shorter distance node. Therefore, more transmission time is given to the shorter distance node and vice versa. This is achieved by assigning dynamic distance adaptive duty cycle to the nodes of the cluster using sigmoid function (SF). The performance of the proposed sigmoid function-based duty cycle (SFDC) strategy has been compared with the other two existing energy optimization protocols: low energy adaptive clustering hierarchy (LEACH) and stable election protocol (SEP). The simulations for the evaluation of all the strategies have been performed on the metrics of packets delivered to base station (BS), number of dead nodes, available network energy utilization, network energy utilization for relaying, and average energy needed (in mJ) for transmission of a packet. These parameters have been calculated for increasing number of rounds and nodes. Results show that packet deliveries for LEACH and SEP (70:30) strategies are 96.93% and 66.87% of the proposed SFDC strategy, respectively. Furthermore, higher network energy utilization and less energy consumption of the proposed strategy have been obtained than other existing strategies.