The technique of cooperative communications is finding its way in the next
generations of many wireless communication applications. Due to the distributed
nature of cooperative networks, acquiring fading channels information for
coherent detection is more challenging than in the traditional point-to-point
communications. To bypass the requirement of channel information, differential
modulation together with non-coherent detection can be deployed. This thesis is
concerned with various issues related to differential modulation and
non-coherent detection in cooperative networks. Specifically, the thesis
examines the behaviour and robustness of non-coherent detection in mobile
environments (i.e., time-varying channels). The amount of channel variation is
related to the normalized Doppler shift which is a function of user's mobility.
The Doppler shift is used to distinguish between slow time-varying
(slow-fading) and rapid time-varying (fast-fading) channels. The performance of
several important relay topologies, including single-branch and multi-branch
dual-hop relaying with/without a direct link that employ amplify-and-forward
relaying and two-symbol non-coherent detection, is analyzed. For this purpose,
a time-series model is developed for characterizing the time-varying nature of
the cascaded channel encountered in amplify-and-forward relaying.Comment: PhD Dissertatio
