Spectral co-existence in cooperative wireless networks

In this thesis, the use of analog network coding for the spectral co-existence of primary and secondary users in flat Rayleigh fading through cooperative relaying has been investigated. It is assumed that the primary and secondary systems are all SISO, and thus a 2x2 SISO-SISO cooperative radio network has been considered for concurrent spectrum sharing using overlay approach. The investigated co-existence assumes placing the secondary signal on top of the analog network-coded primary signals at the secondary relay under two different scenarios, from which both users benefit as to either enable primary transmission not possible otherwise or increase signal quality or both compared to that in the absence of cooperation. Conditions of at least maintaining or increasing the primary user's signal quality compared to that in the absence of cooperation have been analyzed in terms of outage probabilities for both users. Assuming cognitive spectrum sensing, outage probability has also been obtained for the secondary users by generalizing the transmission to the case in which spectrum holes may also be available with some probability.