Multi-relay cooperative relaying enables spatial diversity often at the expense of spectral efficiency. To alleviate the loss in spectral efficiency due to half-duplex relaying and transmission over orthogonal channels, we propose a novel transmission scheme for selective decode-And-forward (DF) networks. In this scheme, we assume that destination may receive signals from transmitting nodes with different modulation levels. Particularly, we obtain a closed-form expression for both end-To-end (E2E) average error probability and spectral efficiency in such scheme. Subsequently, using these closed-form expressions and average channel statistics, we perform joint optimization of power allocation and modulation level selection to maximize the E2E spectral efficiency while maintaining a target E2E average error probability, and a set of transmit power constraints. Simulation results demonstrate that the transmission scheme proposed herein improves the E2E spectral efficiency significantly in comparison with the conventional adaptive DF transmission scheme.

Additional Metadata
Keywords adaptive modulation, Cooperative diversity, selective relaying
Persistent URL dx.doi.org/10.1109/TVT.2016.2607159
Journal IEEE Transactions on Vehicular Technology
Citation
Sokun, H. (Hamza), & Yanikömeroǧlu, H. (2016). On the Spectral Efficiency of Selective Decode-And-Forward Relaying. IEEE Transactions on Vehicular Technology, PP(99). doi:10.1109/TVT.2016.2607159