An Opportunistic Channel Access Scheme with Channel Ordering for Cognitive Radio Network

Spectrum access by an unlicensed secondary user (SU) in a cognitive radio network (CRN) is challenging due to the dynamic nature of spectrum availability and possibility of collisions with the primary user (PU). SU uses a scheme where SU´s packets are interleaved with periodic sensing to detect PU´s return. To utilize spectrum efficiently, this paper proposes an opportunistic spectrum approach with channel ordering and periodic sensing. In the proposed approach, SU first selects a number of channels from ordered channels, senses them for opportunity, and then probes the idle channel for channel quality measurement. SU transmits over an idle channel, and the whole process is repeated for the SU transmissions. This paper presents a simple method for channel ordering, which reduces the channel access time. This scheme considers channel fading and channel availability for channel ordering and opportunity discovery.