Hierarchical modulation-based successive relaying protocol for cooperative networks with interference cancellation

Successive relaying (SR) provides an effective transmission scheme to recover the multiplexing loss of the traditional cooperative networks. However, SR suffers from the inter-relay interference (IRI) problem, which results in transmission error and degrades the system throughput. In order to achieve full-diversity, interference cancellation (IC) is introduced to the reception at relay nodes. To completely eliminate the IRI, most of the previous works require the assumption that the IRI is sufficiently strong or weak in comparison to the source signal; however, this assumption may not sustained in practical environments. Without the need of this assumption, this paper proposes a novel SR transmission protocol and an adaptive decoding algorithm at the receiver. Benefited from the hierarchical modulation (HM) technique, the relay nodes can successfully eliminate the IRI, even when the IRI and the source signal have an equivalent power level. The performance evaluation shows that the proposed HM-based successive relaying (HMSR) protocol can eliminate IRI effectively and outperforms the conventional SR in terms of the error performance and system throughput.