Performance Enhancement using Hierarchical Modulation in Distributed Relaying Systems

Various relay technologies have been considered in wireless communication systems to enlarge the coverage and to enhance the system throughput. However, the coverage is limited by its modulation levels and additional time slot(s) is required for relaying. In the paper, by applying the hierarchical modulation to two-relay systems, two-hop relaying can be implemented instead of three hops, and both throughput and coverage can be enhanced. Throughout simulation analysis, the coverage extension is evaluated for different modulation levels and the total throughput is increased by up to two times.