A Low-Complexity Transmit Cooperation Scheme based on Layered Higher Order Modulation

Abstract

Decode-and-Forward (DF) is a popular approach to transmit information over a cooperative relay channel. However, DF is not optimised for any propagation conditions since it simply combines the received information coming from different sources regardless of their respective link qualities. In this paper, we propose a novel transmit cooperation scheme that can take advantage of asymmetric link qualities using layered higher order modulation. Moreover, this scheme reduces the complexity at the source and relay nodes and transfers most of it to the destination node. This feature can be useful for sensor network applications, where low-complexity nodes are required. Performance evaluation shows that our scheme outperforms an equivalent DF scheme and provides a better spectral efficiency in asymmetric propagation conditions than DF. Additionally, this scheme can accommodate iterative detection to further improve its performance.

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