Optimization of Wireless Sensor Network Lifetime by Deploying Relay Sensors

Topology control in wireless sensor networks helps to lower node energy consumption by reducing transmission power and by confining interference, collisions and consequently retransmissions. Decrease in node energy consumption implies probability of increasing network lifetime. In this paper, first we analyze popular topology control algorithms used for optimizing the power consumption in the wireless sensor network and later propose a novel technique wherein power consumption is traded with additional relay nodes. We introduce relay nodes to make the network connected without increasing the transmit power. The relay node decreases the transmit power required while it may increase end-to-end delay. We design and analyze an algorithm that place an almost minimum number of relay nodes required to make network connected. We have implemented greedy version of this algorithm and demonstrated in simulation that it produces a high quality link. We use InterAvg, InterMax (no of nodes that can offer interference) MinMax, and MinTotal as metrics to analyze and compare various algorithms. Matlab and NS-2 are used for simulation purpose. Keywords: Energy saving, sensor networks, Interference, network connectivity, topology control