ABSTRACT
The dynamic spectrum sharing nature of cognitive radio networks (CNRs) leads to nonnegligible levels of cochannel interference (CCI). This CCI, caused by undetected primary users (PUs) or by other CRNs, can result in significant performance losses. Cooperative spectrum acquisition is investigated in this chapter where different sources of interference are considered. Chase-combining hybrid automatic repeat request (HARQ) and regenerative cooperative diversity are explored in the context of spectrum interweave. The chapter also covers cooperative spectrum acquisition in the context of spectrum underlay where interference is considered as a design parameter. The chapter is organized as follows. Section 4.2 focuses on chase-combining HARQ based on the results of [1–6]. Section 4.3 is devoted to regenerative cooperative diversity in the presence of interference based on [1–6]. Section 4.4 covers spectrum underlay where interference level is a design parameter based on the results presented in [7].
