| As a promising candidate technique of LTE-A, CoMP has potential benefit to improve the coverage of high data rates and to increase both the average cell throughput and cell edge user throughput. For the transmission function of CoMP, eNodeB needs to get all the channel information of the links between users and the cooperation cells, which need to be transmitted by UE. the channel information feedback can be used to implement link adaption and accurate scheduling to improve the performance of the system. But as an extra overhead for the system, it occupies the resources of PUSCH and reduces the frequency efficiency of Up-Link. Hence, it is necessary to design rational feedback scheme to reduce feedback overhead and increase the frequency efficiency under the premise that eNodeB acquire the accurate channel information.In this paper, the feedback mechanisms are investigated for CoMP systems. Specifically, we propose two novel limited feedback schemes with the extension of the traditional approaches. For a CoMP-SU-MIMO scenario, the clustered and fixed threshold SNR limited feedback scheme is developed; While for the CoMP-MU-MIMO model, the best feedback physical resource blocks are chosen and dynamic threshold SNR is selected under the criteria of outage probability. Simulation results demonstrate that the proposed schemes can reduce the feedback greatly in contrast to the traditional algorithm, but merely sacrify little capacity degradation under heavy load. |
