Impact Analysis of Reciprocity Mismatch in Relaying Systems

Abstract

Cooperative beamforming can provide a significant performance improvement for relaying system with the help of the channel state information (CSI). In time-division duplexing (TDD) mode, the estimated CSI will deteriorate due to the reciprocity mismatch. In this work, we examine the impact of the reciprocity mismatch in relaying systems. To evaluate the impact of the reciprocity mismatch for all the devices including sources, relays, and destinations, the closed-form expression of the achievable rate is derived. Then, we analyze the performance loss caused by the mismatch at the source side, the relay side, and the destination side respectively to show that the mismatch at the relay side dominates the impact. Simulation results are presented to verify the analytical results.