Traffic Aware Relay Node Lifetime for Data Collection in Wireless Sensor Networks

For data collection in various environments the wireless sensor networks (WSNs) is used. In that the sensor nodes are randomly deployed in large quantity, there is a broad range of applications supporting manual deployment. The sensors collect the raw data and forward to a remote base station (the sink) through a series of relay nodes. In the wireless communication environment, the operation time of a relay node depends on its traffic volume and communication range. Relay nodes are battery-limited. To get the maximum network lifetime, the location of the relay node have to be carefully planned. The deployment is ensure connectivity between the data sources and the sink, and also hold the heterogeneous traffic flows from different sources and the dominating many-to-one traffic pattern. For the simple case of one source node, both with single and multiple traffic flows produce the optimal solutions. However, the general form of the deployment problem is difficult, and the existing connectivity-guaranteed solutions cannot be directly applied here. The problem is then transformed into a generalized version of the Euclidean Steiner Minimum Tree problem (ESMT). Solution is in continuous space and may yield fractional numbers of relay nodes, where simple rounding of the solution can lead to poor performance. Thus the algorithms are developed for discrete relay node assignment, together with local adjustments. It yields the high-quality practical solutions. The solution has been evaluated through both numerical analysis and ns-2 simulations and compared with state-ofthe- art approaches. Traffic unaware strategies achieves up to 6 to 14 times improvement on the network lifetime.