On Spectrum Heterogeneity and Non-Sequential Spectrum Scanning

One of the fundamental working principles of distributed cognitive radio networks is based on the ability of a cognitive radio to scan and estimate the spectrum bands available for transmission. The spectrum holes or white spaces that would be potentially available are envisaged to be noncontiguous frequency bands of different width distributed over a wide range of spectrum. The distinct characteristics of frequency bands - spectrum heterogeneity - should be included in the spectrum sensing and scanning process. This paper presents a set of non-sequential scanning techniques viz. the bidirectional, dual band and pseudorandom scanning methods to scan the wide spectrum bands. Performance analysis of the scanning techniques is extended to test in heterogeneous and diverse channel occupancy scenarios. The simulation results indicate that non-sequential scanning performs well even in heterogeneous spectrum conditions.