Lifetime optimization using variable battery capacities and nonuniform density deployment in wireless sensor networks

Nodes in a wireless sensor network have nonuniform energy consumption rates. As a result, early death among highly loaded nodes is a common phenomenon which makes it impossible to use the full capacity of the network. In this paper, we propose to deploy sensors either with variable battery capacities or with nonuniform densities in order to counterbalance the nonuniform energy drainage, thus achieving a longer network lifetime. We divide the monitored region into concentric ring areas and deploy nodes in these areas such that the highest battery resources are allocated to the ring where the highest energy drainage takes place. Results show that up to 6 to 7 times longer lifetime values are attained without any increase in costs with this approach.