Research On TD-SCDMA Performance Improvement Based On Joint Detection Technology

The paper is the subtopic of the research and application of the next generation telecommunication network coverage key technology which is Tianjin science and technology innovation special funds project. In recent years, the surging number of mobile communication users, requirements for communication quality and different requirements for communication service contribute to the rapid development of mobile cellular communication technology.With the construction and development of wireless networks, TD-SCDMA (Time Division Synchronous Code Division Multiple Access) communication technology progressively commercializes.But some interference problems exist, such as Multiple Access Interference, which exerts an influence on communication quality and connection rate. Through deep research of the physical layer structure of TD-SCDMA system, Multiuser Joint Detection algorithm and Smart Antenna, an improved algorithm, which combined Joint Detection with Smart Antenna, was proposed in the paper. The simulation results showed that the new method improved TD-SCDMA system bit error rate levels and enhanced the system’s capacity.The following work is mainly completed:1. An in-depth study of the physical layer of the TD-SCDMA system which included principle and function of physical channel, frame structure, emergent structures and training sequence. Also channel estimation model of the system is analyzed.2. The reason of multiple access interference was firstly analyzed, as well as traditional detector; linear Multiuser Joint Detector (Zero-forced detector, MMSE-BLE detector); nonlinear Multiuser Detector(Serial Interference Cancellation detector, Parallel Interference Cancellation detector and Decision-Feedback multi-user detector). The simulation results showed that BER performance of Minimum Mean Square Error algorithm is the best.3. An advanced algorithm-Minimum Mean Square Error algorithm combined Serial Interference Cancellation was proposed.And the realization structure of algorithm was established.At the same time, the simulation model was developed and it can be seen from it that the new algorithm has improved BER performance significantly.4. Smart Antenna was deeply studied, especially Direction of Arrival estimation and Beamforming Adaptive algorithms of smart antenna. Then Joint Detection and Smart Antennas in the TD-SCDMA System were combined together, MATLAB showed the combination contributed to good interference suppression performance and system capacity of TD-SCDMA system.