Wavelet/wavelet packet decomposition has become a very useful tool in describing nonstationary processes. Important examples of nonstationary processes encountered in practice are cyclostationary processes or almost-cyclostationary processes. In this paper, we study the statistical properties of the wavelet packet decomposition of a large class of nonstationary processes, including in particular cyclostationary and almost-cyclostationary processes. We first investigate in a general framework, the existence and some properties of the cumulants of wavelet packet coefficients. We then study more precisely the almost-cyclostationary case, and determine the asymptotic distributions of wavelet packet coefficients. Finally, we particularize some of our results in the cyclostationary case before providing some illustrative simulations
In this paper, optimal and suboptimal routing protocols are proposed for cognitive radio networks. We first investigate optimal routing protocol that consists in searching among all available paths, the one that minimises the end-to-end outage while verifying interference constraint to primary receiver. A suboptimal one-hop routing protocol is proposed where the best relay is selected in each hop. The last routing protocol consists in decomposing the network in many subnetworks composed of K hops. Then, the best route is determined in each of these subnetworks so that the K-hops outage probability is minimised. The proposed K-hops routing protocol allows a good compromise between complexity and performance. The outage probability of the different routing protocols is evaluated theoretically and through simulation results.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.