Research On Energy Saving Strategies In Wireless Sensor Networks

Wireless Sensor Network (WSN) is an intelligent network with energy-constrained and storage-limited nodes deployed in sensing fields.It is able to collect the sensed information and transmit to the user via collaborative efforts.The nodes, however, are typically powered by batteries and it is difficult to replenish the energy after deployed, thereby one main concern for protocols of wireless sensor networks is how to manage the limited battery resource and balance the energy consumption of all nodes thus to maximize the network lifetime.This paper mainly studies on energy saving strategies of network layer. Two clustering routing protocols (RELCRP and UCBCRP) are proposed in this paper addressing to solve the "hot-spot" problem.In RELCRP, it was introduced that a priority based cluster head selection strategy in which node with higher priority was supposed to broadcast cluster head election notice much earlier, while accordingly node with low residual energy was averted to become a cluster head. In inter-cluster communication, a hybrid transmission mode of single-multi--hop was adopted. The cluster head switched transmission mode according to residual energy level of its neighboring cluster heads and itself so as to alleviate the "hot pot" problem induced by multi-hop transmission.An uneven clustering strategy which divides the whole network into several rings is introduced in UCBCRP.The spans of different rings are controlled by a parameter so as to balance the energy consumption of nodes in different rings.Rings nearer to the sink has smaller span as well as cluster size, therefore, cluster heads in inner rings consumes less in the intra-cluster communication. Besides, an energy feed-back strategy is adopted to reach balanced energy consumption. Cluster heads with remaining energy less than TE_MIN are prohibited to forward data of outer rings and are only responsible for transmitting data of their own cluster thus save energy.The effectiveness of the two protocols is proved by a number of simulated experiments and simulation results indicate that RELCRP and UCBCRP efficiently balance the energy consumption of all nodes.Compared to LEACH, the two protocols extend the network lifetime respectively by 40% and 185%.