Cooperative communication techniques for spectrum sharing

This chapter considers different aspects of coordination within a spectrum sharing environment, with the existence of imperfect and possibly even distributed channel knowledge across the system. Concentrating on the design of enhanced performance transmission (reception) schemes for downlink (uplink) communication, such partial channel knowledge at the transmitter (receiver) side is represented by a realistic model. Providing an assumption on statistical cooperation, with regards to channel information and the activity profile of the primary service, the chapter emphasizes the notion of service coexistence through formulating problems, the aim of which is to optimize the data transmission/reception and/or the spectrum sensing parameters. Considering such a service prioritization framework, enhanced mobile broadband services are efficiently multiplexed. The chapter exploits the advantages of a hybrid interweave/underlay cognitive radio system design, a secondary service in need of high data rates effectively coexists in space and in time with a high reliability service running at the primary system side.