Research On Feedback For Multi-cell MIMO

For next generation communication system, increasing the system and cell-edge throughput by using coordinated multi-point (COMP) transmission is of particular interest . In COMP, the base stations can transmit signal to a cell-edge user together. On the other hand, in wireless MIMO communication system, the mobile station can report the channel information to improve the system. In COMP, how to feedback is studied on in the paper.In the paper, the MIMO, precoding, LTE and COMP are introduced. In COMP the feedback can be reported in two manners: joint report and disjoint report. Joint report means The UE reports a single report which is computed jointly for all the cells. Disjoint report means the report is computed separately for each of the cells. Joint report should be better. And we prove this by analysis and simulation.Joint report can be designed in two manners: Joint design and Disjoint design. Though joint design can get more system benefit, it is not flexible enough. Then disjoint design is introduced. The codebook is formed by concatenating common single-cell codebooks. And we improve disjoint design codebook by feedback time delay. We compare the improved codebook with original one by simulation and prove that the improved codebook is better.