A spectrum aggregation algorithm with minimum spectrum switch for CR enabled TD-LTE on TVWS

Abstract

In this paper, how to aggregate and allocate idle TVWS (TV White Space) bands for CR (Cognitive Radio) enabled TD-LTE (Time Division Long Term Evolution) system is investigated. Considering the limited spectrum aggregation capability of TD-LTE terminals, a Spectrum Aggregation algorithm with Minimum Spectrum Switch (SAMSS) is proposed to utilize the relatively wide and dynamic TVWS. Based on the theories of semi-Markov process and alternating renewal process, channel usage states of TVWS are constructed as an ON-OFF alternating model. Then, transition probabilities of the channel usage states are calculated and switching probability of the aggregation region is estimated by asymptotic analysis. The proposed algorithm finally selects the aggregation region with the smallest switching probability for UEs to minimize the number of spectrum switches during multiple sensing and transmitting periods. Numerical results show that the proposed algorithm outperforms the traditional methods by effectively reducing the number of spectrum switches in a long span of time, whilst guaranteeing favorable system access performance such as the total number of working UEs. © 2014 Springer International Publishing.