By: Lichuan Liu
Advisor: Hongya Ge
Department of Electrical and Computer Engineering

Time: 10:30 AM, Tuesday, December 13th, 2005.
Place: Room 202, ECE Center, New Jersey Institute of Technology, Newark NJ. Directions

Abstract

In recent years, the idea of wireless sensor networks has gathered a great deal of attention. A distributed wireless sensor network may have hundreds of small sensor nodes. Each individual sensor contains both processing and communication elements and is designed to monitor the environmental events specified by the end user of the network. Information about the environment is gathered by sensors and delivered to a remote collector.

This research conducts an investigation with respect to the energy efficiency and the cross-layer design in wireless sensor networks. Motivated by the multipath utilization and transmit diversity capability of space-time block codes (STBC), a new energy efficient cooperative routing algorithm using STBC is proposed. Furthermore, the steady state performance of the network is analyzed via a Markov chain model. The proposed approach in this dissertation can significantly reduce the energy consumption and improve the power efficiency. This work also studies the application of differential STBC for wireless multi-hop sensor networks over fading channels. Using differential STBC, we select multiple sensors acting as parallel relay nodes to receive and relay collected data. The proposed technique offers low complexity, since it does not need to track or estimate the time-varying channel coefficients. Analysis and simulation results show that the new approach can improve the system performance. Moreover, a packet collision model for crucial nodes in wireless sensor networks is introduced. Using such a model, we present a space and network diversity combining (SNDC) method to separate the collision at the collector. The network performance in terms of throughput, delay, energy consumption and efficiency are analyzed and evaluated. We investigate the impact of network resource constraints on the performance of multi-hop sensor networks with cooperative relay. This dissertation models the cooperative relay method for sensor networks using a Markov chain and an M/G/1 queuing system, and studies the system performance when infinite buffer and finite buffer are used. The analytical and simulation results indicate significant system improvements in terms of system capacity. Moreover, the go through delay and the packet drop probability are also improved compared to traditional single relay method.

Committee Members:
Hongya Ge, Advisor, Associate Professor, ECE Dept., NJIT
Swades De, Assistant Professor, ECE Dept., NJIT
Teunis J. Ott, Professor, CS Dept., NJIT
Roy You, Assistant Professor, ECE Dept., NJIT
Mengchu Zhou, Professor, ECE Dept. , NJIT