Year: 2009
Type: dissertation
Abstract: With the growth of wireless networks such as sensor networks and mesh\nnetworks, the challenges of sustaining higher data rates and coverage, coupled\nwith requirement for high quality of services, need to be addressed. The use\nof spatial diversity proves to be an attractive option due to its ability to\nsignificantly enhance network performance without additional bandwidth\nor transmission power. This thesis proposes the use of cooperative wireless\nrelays to improvise spatial diversity in wireless sensor networks and wireless\nmesh networks. Cooperation in this context implies that the signals are\nexchanged between relays for optimal performance. The network gains\nrealised using the proposed cooperative relays for signal forwarding are\nsignificantly large, advocating the utilisation of cooperation amongst relays.\nThe work begins with proposing a minimum mean square error (MMSE)\nbased relaying strategy that provides improvement in bit error rate. A simplified\nalgorithm has been developed to calculate the roots of a polynomial equation.\nFollowing this work, a novel signal forwarding technique based on convex\noptimisation techniques is proposed which attains specific quality of services\nfor end users with minimal transmission power at the relays. Quantisation\nof signals passed between relays has been considered in the optimisation\nframework. Finally, a reduced complexity scheme together with a more\nrealistic algorithm incorporating per relay node power constraints is proposed.\nThis optimisation framework is extended to a cognitive radio environment\nwhere relays in a secondary network forward signals without causing harmful\ninterferences to primary network users.
Author: R. Krishna
Language: English
Subfield: Computer Networks and Communications
Field: Computer Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W783979939