Avoiding energy holes in wireless sensor networks with non-uniform energy distribution

This paper proposes a non-uniform solution to the energy hole problem. The network is formed by a large number of tiny sensors, randomly scattered over a circular area and the sink positioned at the center. The sensors produce data with the same rate and the data travels from the nodes to the sink in a multi-hop fashion, using a shortest path routing. The basic idea, in order to avoid the energy hole around the sink, is to equip each network area with so much energy as the traffic load of that area. Firstly, a pure analytical expression for the traffic load is derived and then, based on this expression, a non-uniform deployment is proposed, with variable surface density, for a certain number of dormant nodes. Each time an active node exhaust its battery, a near dormant node becomes active and takes its place. The proposed strategy improves the network lifetime by a factor of 50 and the energy utilization by a factor of 6, compared to a conventional network without dormant nodes.