Balanced Use of Battery Power in Ad-hoc Wireless Sensor Networks

We focused on a problem where balanced use of sensor nodes' battery power is considered to maximize the overall lifetime of ad-hoc Wireless Sensor Networks. A process in which utilizing less attended sensor nodes compare to sensor nodes which are used more frequently enhances the overall network lifetime. To perform this process, we propose a joint optimization problem to select a subset of active sensor nodes and a multi-hop routing structure interconnecting all selected sensor nodes, which helps to route the aggregated information to a querying node. Our optimization problem becomes non-convex over the subset selection and the multi-hop routing paths selection, thus belonging to the class of NP-hard problems. We solve our problem by relaxing one of the variable so that optimization problem becomes convex over this variable, which can be solved efficiently. We also propose an iterative algorithm to solve this problem distributively. We demonstrate by extensive simulation that the above mentioned both the approaches increase the overall network lifetime for a given power budget. One another important result is that the distributed approach provides an optimal routing structure considering over the well known shortest path tree based routing structure.