Bit allocation strategy among users in coordinated multi-cell systems with limited feedback

In this paper, we propose a novel bit allocation strategy in coordinated multi-cell systems with limited feedback. Multi-cell cooperation technique is an effective way to improve the system throughput and especially the performance of the cell edge users. In a Coordinated Multi-Point (CoMP) system, the rate loss caused by quantization error of Channel State Information (CSI) is minimized considering two aspects of the channels. Firstly, as the physical conditions and constraints of different users are not identical, appropriately allocating feedback bits to users based on their channels can achieve higher throughput. Secondly, in a Coordinated Beamforming/Coordinated Scheduling (CB/CS) system, each user has a serving channel to the serving base station and an interfering channel to the coordinated base station. The user needs to partition its available bits between the two channels. Thus, we study a global bit allocation strategy that can minimize the rate loss from that of the full CSI circumstance. From our simulation results, we prove that the proposed bit allocation strategy achieves higher per-cell sum-rate compared with the equal bit allocation strategy.