A novel precoding scheme in coordinated multipoint transmission systems

Coordinated Multi-point Transmission/Reception (CoMP) has been identified as a promising technology to improve cell-edge user performance and cell coverage in 3GPP LTE-Advanced (LTE-A) system. Joint processing (JP) technique is one major category of CoMP, where exactly the same data is simultaneously transmitted from multiple transmission points (TPs). This transmission fashion, however, demands a large amount of data exchange among TPs as well as comprehensive computation for UE if closed loop MIMO is utilized. To solve such an issue, we develop a novel adaptive JP scheme, in which only one transport block (TB), experienced by the serving point under worse channel condition, is transmitted from coordinated TPs. Hence, the precoding matrix of coordinated TPs only targets a subset of layer-data transmitted from serving point. Validated by theoretical analysis and simulation, the proposed scheme exhibits good quality of lower computational complexity for UE and less data exchange among TPs; moreover feedback overhead is reduced when co-phasing is adopted to implement coherent transmission. Meanwhile the scheme preserves good performance as conventional local precoding. According to simulation results, the performance achieved by our raised JP scheme approaches to that by conventional local precoding when coherent transmission is permitted, and particularly when noncoherent transmission is done at transmitter.