Modeling and analysis of traffic‐aware spectrum handover schemes in cognitive HetNets

AbstractCognitive radio (CR) heterogeneous network (HetNet) is an emerging technology that aims at enhancing spectrum utilization through spectrum sharing among macro base stations and femto base stations. Similar to other CR networks, in CR HetNets, providing the desired quality of service for the licensed primary users (PUs) is of utmost importance. Due to the shared spectrum between PUs and cognitive secondary users (CSUs) as well as offloading policies, the spectrum handover (SHO) process must be carefully designed. Using the idea of reserved channels, this paper proposes 2 traffic‐aware SHO schemes for cognitive HetNets. In the proposed schemes, each CSU can adopt either a shared‐to‐reserved or a reserved‐to‐shared SHO strategy. The proposed approaches can be implemented in both distributed and centralized manners to maintain a trade‐off between performance and complexity. The performance of the proposed schemes is mathematically analyzed, and closed‐form expressions are derived for the blocking probability of the PUs and the forced termination probability of the CSUs. Numerical results show that the proposed schemes outperform the existing SHO approaches, such as always‐change, always‐stay, and proactive methods, specifically at higher arrival rates of PUs. Moreover, several evaluation metrics, such as effective throughput, energy efficiency, and a proposed combinational utility function, are investigated for both distributed and centralized schemes. The results show that the proposed centralized schemes offer higher performance compared to the distributed schemes.