A Relay-Assisted Protocol for Spectrum Mobility and Handover in Cognitive LTE Networks

Most of the licensed and license-exempt bands are underused while usage in some unlicensed bands is increasing. This trend has driven unlicensed users, equipped with cognitive radios, to opportunistically and dynamically access the spectrum not used by licensed users. Relaying techniques are an important issue for coverage and capacity extension. In this paper, we describe a relay-assisted protocol for spectrum mobility and handover with minimum expected transmission times in cognitive long-term evolution networks, which allows unlicensed users access to not only the previous base stations but also the next base station, with the assistance of relay nodes. Performance analysis of the proposed handover protocol is investigated, and simulation results of the proposed handover protocol are presented, which illustrate a significant reduction in total transmission time and spectrum mobility ratio, and increases in throughput.