Abstract

Wireless sensor networks (WSNs) are commonly used in many applications. The energy efficiency of the system has become the subject of extensive research lately. In this thesis we will introduce relay selection schemes that attempt to optimize the transmission of data. We use a two phase WSN model where a message is broadcasted from the source then relayed by the overhearing sensors (nodes) to a fusion center (FC). These schemes will reduce the number of bits transmitted from the sensors to the destination as well as minimize the activity of these sensors and lead to a more energy efficient system. The main idea is to have the smallest subset of sensors that contain the entire information relay the message; in an ideal situation the subset will only contain a pair of sensors.

We then investigate the addition of error correcting codes (ECCs) to the node-FC channels. We observe the outage probability of the relay selection schemes using turbo codes on the node-FC channels. We also examine the expected number of bits (including extra parity bits) in the transmissions. We show that under certain channel conditions introducing turbo codes to the node-FC channels leads to longer sensor lifetimes.