Cooperative spectrum sensing methodology for cognitive radios through scheduling/ tasking

Abstract

The rapid advancement in the field of wireless communications that has been expedited by the commercial demand for better services has led to the application of wireless systems in many fields of life. Ranging from military radio communication systems, to cellular systems and wireless sensor networks; purposely emitted radio waves occupy major parts of the frequency spectrum. The past few decades have seen the development of many wireless systems that have been permanently allocated spectrum by regulatory authorities. Direct and indirect observation of spectrum usage has identified the temporal and spatial availability of spectrum within allocated frequency bands. This implies that although spectrum scarcity is becoming a major problem, however intelligent access to pre-allocated spectrum has the potential to enable usage of licensed spectrum by unlicensed users on the pre-agreed condition of minimum interference. Cognitive networks promise to solve these problems of spectrum scarcity by accommodating unlicensed (secondary) users in under-utilized segments of the spectrum. Spectrum sensing forms the primary stimulus for a cognitive radio and is vitally important for ensuring that the unlicensed users do not offer intolerable levels of interference to licensed (primary) users. Cooperativespectrum sensing provides the capability to cognitive networks to overcome problems related to “hidden” primary users. In this research, we have presented a novel strategy that takes advantage of cooperative diversity to establish grouping among cooperating secondary users. This strategy is then extended to group-based spectrum sensing to establish a scheduling/ tasking mechanism. The strategy ensures enhanced agility that will result in a reduction of interference to primary users through their early detection