Research On Timing And Frequency Synchronization For Coordinated Multipoint-to-Multiuser Systems

With the development of human society, the demand for communication services is growing bigger and bigger, and the requirement for quality of service communication is increasing higher and higher, all of which, promotes the development of the new generation of broadband wireless communication technology. In order to improve the system throughput and the quality of service, many new technologies have emerged in the field of modern communication technology, such as the enhanced Multiple-Input Multiple-Output (MIMO), Space-time Coding, Coordinated Multiple Points Transmission and Reception (CoMP) technology, and so on. Multiuser coordinated multi-point transmission (MU-CoMP) system has become a hotspot of current research. However, the time and frequency synchronization have not yet completely solved for the system, especially in high-speed mobile environment, mainly shown in two aspects, signal timing offsets (STOs) compensation and carrier frequency offsets (CFOs) compensation; besides, the synchronization problem can’t be solved by the traditional compensation algorithm.Based on this existing issue, we propose a joint pre-and post-compensation algorithm associated with relaxed residual STOs and CFOs, namely, pre-compensate in base stations and post-compensation in mobile terminals, so as to mitigate the offsets effectively to the tolerable values, realize the goal of transmitting information correctly. In the paper, we firstly prove the offsets can’t be completely eliminated; then we model the problem as a constrained optimization problem; by solving the problem we can get the pre-compensation values and the post-compensation values. Simulation results indicate that the algorithm is capable of mitigating the STOs and CFOs effectively to tolerable values, and meet the requirement of synchronization..