Information propagation in wireless sensor networks using directional antennas

The information propagation capability of Wireless Sensor Networks (WSN) is directly related with the properties of multihop paths. Two main measures of the multihop data propagation capability are the maximum Euclidean distance that can be covered in a multihop path and the effectiveness of the medium access control (MAC) protocol. To achieve high propagation capacity, MAC protocols should enhance the channel use by maximizing simultaneous traffics and reducing end-to-end delay in high data load scenarios often encountered in WSN data collection applications. In this regards, directional antennas offer various benefits such as the extended communication ranges, spatial reuse capability, and reduced interference patterns that enable higher network performance compared to omnidirectional antennas. In this thesis, the maximum multihop Euclidean distance covered by directional packet transmissions is evaluated for both linear and planar WSNs using analytical modeling of distance distributions. Expressions for calculating the distribution parameters are derived and provided. Comparison of experimental and analytical results demonstrate the high accuracy of the proposed models in estimating distance distributions. Furthermore, a WSN security application which utilizes the derived models for verifying sensor locations is presented. The second contribution of this thesis is the Smart Antenna-Based MAC (SAMAC) protocol designed for multihop data collection applications for WSNs with sectored antennas. A detailed protocol description as well as performance evaluation results are provided. Simulation results demonstrate that SAMAC with sectored antennas improves end-to-end delay, data throughput, and data delivery ratio under high data generation rates and highly loaded traffic conditions compared to IEEE 802.11 with omnidirectional antennas.