Optimization Research On Wireless Sensor Netwok Lifetime

As a novel way of acquiring and processing information, wireless sensor networks have been an attractive research hot-spot all over the world. In wireless sensor networks, the energy is very limited, and can not be complemented in most situations. How to effectively use the limited energy to prolong the lifetime of the network is the key of improving network performance.The main contributions of the thesis are listed as follows.In flat routing protocol, nodes transmit data to sink by multi-hops, that lead to the fact that the nodes around sink die ahead of time because they transmit more data. In order to prolong the lifetime of wireless sensor network, we add some relaying nodes in the position around the sink. First, the thesis calculate the ideal number relaying nodes under the energy balance circumstance. But if we add too many relaying nodes in ideal circumstance, it lead to data congestion and resource waste easily. So we take the method of reducing the number of relaying nodes and increasing their energy into account. Simulation result indicates that , when the number of relaying nodes is zero point eight of the ideal one, the network lifetime is comparativelylarge prolonged.In hierarchical routing protocol, this paper present a clustering algorithm based on residual energy and node degree(BREND). In cluster heads election phase of every round, by twice clustering election for the final cluster heads, it considers the residual energy and nodes degree of all the nodes in each cluster. In addition, it adopt temporary cluster heads quiting strategy, that is there is only one temporary cluster head in a node communication scope, which makes cluster heads distribution more equably. Simulation results show that, in comparison with LEACH and ENCA, the network lifetime is efficiently prolonged.