Investigation of dynamic spectrum assignment schemes for cognitive wireless networks and reduced complexity equalization techniques in aeronautical telemetry channels

This thesis spans across two different research areas in the field of communications. The first part deals with dynamic spectrum assignment policies for the secondary users in cognitive wireless networks and second part shows how reduced complexity Viterbi decoders can be utilized to combat frequency selective fading in aeronautical telemetry channels.;In a cognitive wireless network, sudden arrival of a primary user could force one or more secondary users to terminate their ongoing communication. We demonstrate that depending on the network condition, the proposed spectrum assignment scheme is capable of reducing dropping probability by a factor of 6 -- 7 compared to the conventional network.;High data rate communication between airborne vehicles and ground stations over a multipath channel necessitates equalization at the receiver to remove the detrimental effects of frequency selective fading. It is shown that equalization based on reduced complexity Viterbi decoders outperforms the existing linear equalizers followed by symbol-by-symbol detectors.