Figure 5

Ergodic sum rate for the OP-SI scheme with channel estimation errors. Figure5 shows the ergodic sum rate for the OP-SI scheme. The number of users is fixed as M=2, and the number of relay antennas is N=3, while${\sigma }_{\mathbf{e}}^2$, which is the variance of channel estimation error, are set as 0, 0.01, 0.05, and 0.1, respectively. The simulation results show that the performance of OP-SI scheme is severely impacted by the channel estimation error.