The Improved Scheme of Prolong-Lifetime in Wireless Sensor Networks

Due to the limited transmission range, data sensed by each sensor has to be forwarded in a multi-hop fashion before being delivered to the sink. The sensors closer to the sink have to forward comparatively more message than sensors at the periphery of the network, the nodes will deplete their batteries earlier. Besides the loss of the sensing capabilities of the nodes close to the sink, a more serious consequence of the death of the first tier of sensor nodes is the loss of connectivity between the nodes at the periphery of the network and the sink. It makes the wireless networks expire. To alleviate this undesired effect, we adopt two improved schemes. The first one is to redistribute the total energy budget with data traffic load; the second one is to balance the uneven traffic by power control method. They maximize the useful lifetime of the network. We show by theoretical analysis, as well as simulation, that they substantially improve the network lifetime.