A Precoding Compensation Scheme for Heterogeneous Communication Networks With CSI Feedback Delay

In the 5th generation cellular systems, heterogeneous communication networks allow multiple base stations (BSs) to serve the users cooperatively, which can satisfy the requirement of growing data rate and optimum coverage. However, suffering from the imperfect channel state information (CSI) feedback, optimal performance may not be guaranteed for coordinated multiple point (CoMP) scenarios when certain users are served by multiple BSs, simultaneously. To this end, it is essential to develop transmission schemes with imperfect CSI to improve the performance in CoMP systems. Under the circumstance that an edge user is served by a primary BS and coordinated BS with the same time-frequency resource, at which the CSI can be outdated at the coordinated BS, in this paper, we propose a precoding compensation scheme at the primary BS to eliminate the interference caused by outdated CSI at the coordinated BSs. Two algorithms, namely, maximum signal-to-interference-plus-noise ratio (MaxSINR) and minimum-mean-square-error (MMSE), are proposed for the precoding at the transmitter and the detection at the receiver, respectively, to further improve the performance as well as mitigate the interference. Simulation results show that our proposed transmission scheme is able to provide sufficiently good performance comparing to that of the perfect CSI feedback scenario.