Energy efficiency in wireless sensor networks

Wireless Sensor Networks (WSNs) are consists of small sensor nodes with limited battery power, processing and memory units. There are two important features in WSNs. The first one is the infrastructure-less and second one is the self-organization. These properties make sensors convenient choice for several applications. When we try to investigate algorithms and protocols for wireless sensor networks we must study the features and constraints of WSNs. However, battery recharge is not possible or extremely challenging for sensor nodes. The main aspect in designing wireless sensor networks algorithms and protocols is ensuring energy efficiency and prolong the sensor network lifetime. Farther more the sensor node position within the set of deployed nodes decides which tasks have to be carried out and how many communication paths involve each individual sensor node. On the other hand the sensor networks in more obstructed environments, the path loss exponent value is vary. The high path loss exponent value increases unbalance energy depletion between nodes. In this thesis we investigated two node deployment strategies which are uniform and non-uniform (normal distribution) sensor node deployments with various path loss exponent values. We used a Linear Programming (LP) framework to analyze the effect of node deployment model on the network lifetime. Also we studied the effect of path loss on the wireless sensor network lifetime. Our results showed that by normal node deployment, energy balance can be improved up to certain level. However, increasing path loss exponent in normal node deployment may lead to decrease in improvement ratio.