A novel spectrum sensing and accessing framework for cognitive radio in mobile environment

To help unlicensed users to use the maximum available licensed bandwidth, an opportunistic communication technology called cognitive radio, (CR) is developed. It has recently attracted a great deal of research interest. Even though the majority of future wireless devices will be mobile, mobility is yet unexplored in the context of CR. There is no proper framework for mobile CRs to effectively use the available licensed bandwidth. In this paper, a spectrum sensing and accessing framework considering user mobility is proposed. This work removes all the presumptions about user mobility, established in the previous CR based literature. The smooth random mobility model is considered for creating a realistic mobile environment. The CRs are free to travel and cooperate to sense and use the licensed channels. A cognitive base station coordinates all the CRs. The nodes are grouped into clusters based on their geographical placement and all the nodes in a cluster are further split up into small groups based on their relative mobility. Transform Domain Communication System, (TDCS) is employed by the CRs to access the spectrum. The sensing technique being used by each CR is the double threshold energy detection method. Under this framework, the whole licensed channels can be exploited in each cluster if there are enough number of CRs in that cluster. A Matlab simulation is provided for examining the efficiency of the proposed framework.