On the Optimality of Multi-User Coordinated Zero-Forcing Beamforming Multicell Systems with Limited Feedback in Interference Channels

Abstract

An efficient multicell coordinated zero-forcing channel feedback scheme is proposed in this paper. The objective of the proposed feedback design is to control the rate of the user by adaptive allocation of feedback bits of each user as a function of individual channel status thereby keeping the total feedback budge constant. The proposed feedback allocation is studied in interfering broadcast channel (IFBC) and also in time varying channels (TVC) with feedback update duration. First the individual feedback rates of user are derived using convex optimization thereby presenting low complexity algorithm to optimize the channel feedback between inter-user interference and inter-cell interference. The rate offset arising from channel quantization in both IFBC and TVC is investigated by employing the coordinated zero forcing beamforming. Moreover, closed form expressions are derived for necessary feedback scaling and frequency of update duration to achieve the multiplexing gain and throughput. Finally, numerical evaluation results show that the proposed channel feedback schemes outperforms other conventional schemes and assist in base station cooperation management. It can be concluded that frequent update of channel state information and suppression of dominant interferences can yield significant improvements in the sumrate performance of limited feedbback systems.