Research And Realization Of Synchronization Technology For TD-SCDMA Cell Search

With the acceleration of the process of social information, the existing second generationmobile communication systems have been unable to meet the people's demand for a widerange of mobile communication services. TD-SCDMA is accepted as one of the mainstreaminternational 3G standards with our own intellectual property rights. It has adopted manyadvanced technologies, such as smart antenna, jointed detection, synchronous CDMA and soforth, with the advantages of low transmission power, high spectrum e?ciency and ?exibilityfor asymmetric tra?c services, which lead to a great development potential of market, coupledwith the huge Chinese market attractiveness and the Chinese government's strong supports.And it has became the focus of research and development in recent years.The TD-SCDMA standard makes use of TDD ( Time Division Duplex ) synchronousCDMA technology, adjacent cells share the same frequency, the user data in downlink anduplink time slots was send in di?erent time slot. The cell can change location of the pointfor adjusting the number of uplink and downlink time slots in order to satisfy the the currentdemand for data services. The cell search refers to that it must search for a suitable cell assoon as possible after the user opened the phone in order to use network services. Terminalsmust establish downlink synchronization with base station by searching the SYNC-DL code,which is scheduled for 64-bits PN sequence by system, to obtain the current and adjacent cellinformation. The main operation performed in traditional algorithm is the correlation betweenthe received signal and the known synchronization sequences transmitted in the frame, result-ing in a long time, high power consumption, high degree of complexity and it is limited tothe application. Therefor, we carefully studied the TD-SCDMA physical layer structure andproposed a novel cell search method based on its special frame structure. By this scheme to getthe coarse synchronization, we limited the scope of SYNC DL in a small chip range in whichthe correlation calculate is needed. Then we use the Peak Average Ratio ( PAR ) of charac-teristic of the auto-correlation and cross-correlation of the SYNC DL in DwPTS time slot toget the correlation decision, which e?ectively degrade the complexity of realization。Morever, an effective realization of FPGA is completed in detailed. The simulation and tests show theadvantages of simple, fast, low complexity and high accuracy in a large range of Signal NoiseRatio ( SNR ) environment, compared to the traditional algorithm. This would be valuable tothe research of low cost TD-SCDMA equipments.