Research On Techniques Of Transmit Schemes And Feedback In CoMP Systems

IMT-A system requires high frequency reuse factors or even full frequency reuse to improve the systems ability to achieve high frequency, forming a bottleneck that those cells are interacting each other, decreasing the throughput and limiting the further development of IMT-A system. However, a new technology called COMP can increase the throughput of cells by implementing resources such as, multi-cells, multi-users and multi-antennas, therefore, COMP technology has been accepted by professionals in the communication engineering industry.Nevertheless, some unpredictable problems have been forming as the new technology is been adopting, for example, arrive time mismatch in transmitting data and large feedback overhead. This paper primarily emphasizes two research directions of COMP system, one is to design a joint transmitting plan and the other is to reduce the feedback overhead.Based on two-stage phase compensation method, the paper suggests a precoding proposal that could conquer the current disadvantages in which different cells are inefficiently performing in the arriving time mismatch circumstance. Simulation results indicate that the revised method has better performance in dealing with the arrive time mismatch and it boosted the system's performance in different delays condition.For the research on feedback, the paper focuses on a series of ways of automatic differential code in fast changing channels, in order to overcome the problem that traditional differential code would work poorly in the fast changing channels. Simulation results show that the new method has a better performance compared with the traditional method.