Signal Space Diversity in Decode-and-Forward Cooperative Communication

In Decode-and-Forward (DF) cooperative communication, cooperative nodes decode and retransmit each others' data to achieve spatial diversity. However, asymmetric inter nodes channel can cut down the performance of plain DF; and besides, simple signal retransmission for each other in plain DF is not an efficient diversity manner. In this paper, we propose a new DF cooperative scheme based on signal-space diversity, which can defeat the effect of asymmetric inter nodes channel and utilize diversity more efficiently. Compared with plain DF cooperative scheme, the new cooperative scheme only adds, a rotation and superposition operation on local and relay symbols before relaying, which only introduce a little more complexity at cooperation nodes. Simulation results show the new cooperative scheme achieves better bit-error rate performance than the plain DF cooperative scheme.