Analysis and performance evaluation of an efficient handover algorithm for cognitive HetNets.

Cognitive heterogeneous network is a promising technology to meet the requirements of future wireless networks in cost and energy efficiency. By using vertical handover (VHO) between different network tiers, such as macro and femto, the traffic congestion can be potentially alleviated, and the spectral efficiency is significantly increased. However, performing VHO for a cognitive handover user (CHU) and simultaneously guaranteeing the quality of service of the primary user (PU) is the most challenging issue in such a network. This paper proposes an efficient VHO strategy in a cognitive heterogeneous network, which considers both adaptive average received signal and spectrum availability, namely, average received signal and spectrum availability. To analyse the performance of the proposed average received signal and spectrum availability algorithm, several metrics are investigated. First, the assignment probability of a CHU from a macro base station to a femto base station is evaluated and simplified in a closed-form expression. Then, the outage probability of a CHU and collision probability of the PU are theoretically investigated for the proposed algorithm and are compared with 2 well-known algorithms, the modified received signal strength-α and the received signal strength and wireless transmission loss. We also introduce a new performance metric, referred to as figure of merit, which jointly considers the assignment and outage probability of a CHU, collision probability of a PU, and the number of unnecessary handovers of a CHU. Figure of merit effectively shows the superiority of the proposed handover algorithm to conventional ones. [ABSTRACT FROM AUTHOR]