Performance improvement of layered modulation based cooperative relaying scheme

Abstract

Cooperative communication is a novel approach utilizing limited resources to get reliability. However, overall transmissionrate is reduced to have decomposable composition at the destination node in time-division multiple access (TDMA) system, which diminishes the advantage of cooperation. Recently, a novel use of layered modulation and an adequate cooperative space-time block code (C-STBC) were proposed to solve this drawback. Even though it provided certain level of diversity gain without transmission-rate loss, there is room for improvement. In this paper, we enhance it through the constellation modification and adaptive cooperation schemes. Their effectiveness is evaluated for the multiband orthogonal frequency-division multiplexing (MB-OFDM) system.

Hierarchical modulation-based cooperative scheme: Minimizing the symbol error probability

“…The HM-based cooperative protocol studied in this paper is similar to the one proposed in [9] and further studied in [10]. However, a slight modification of the signals sent by the relay has been introduced in order to simplify the theoretical analysis.…”

“…However the authors considered a broadcast channel with two non-cooperative receivers, and thus did not exploit the diversity of the wireless channel. A HM-based cooperative protocol has been proposed in [9] and further studied in [10]. The authors proposed to exploit diversity by implementing a distributed Alamouti code [11] and studied the simulation performance of this protocol.…”