An Improved Beamforming Schemes in Coordinated Multi-Point Systems

The capacity of modern cellular wireless networks is mainly limited by inter-cell interference (ICI). Coordinated multi-point (CoMP) transmission and reception were adopted as key techniques for Long Term Evolution-Advanced (LTE-A) as they are capable of mitigating ICI through cooperation between several cell sites. Therefore, CoMP techniques provide a significant improvement in cell-edge and average throughput. For downlink CoMP, most research work mainly focuses on joint processing/transmission (CoMP-JP) mode. However this mode needs the access points (AP) to share the UEs' data and channel state information (CSI) simultaneously, resulting in a high overhead on the network. Coordinated beamforming (CoMP-CBF), which can avoid the data information exchange is a better solution to reduce the overhead. In this paper, an improved cooperative beamforming schemes for downlink Coordinated Multi-point System is described. The proposed improved beamforming schemes rely on the principal eigen-vector feedback schemes (e.g. codebook based). Although the description of the beamforming schemes is not a part of specification, the detailed information on the used coordinated beamforming approaches is important for performance evaluation and calibration of the results during CoMP phase. System-level simulation results demonstrate that the proposed scheme can significantly reduce the ICI, and it performs well even with imperfect channel-state information (CSI) at the transmitter.