Research And Implementation Of Initial Multi-cell Search Algorithms In WCDMA

WCDMA is the most widely used wireless access technology in the third generation mobile communication system.At present,more than 90% of the global operators in the use of WCDMA,it can be predicted that,in the case of global operators deploying LTE network,WCDMA will continue to exist and improve.The initial multi-cell search in WCDMA plays an important role for WCDMA base station testing equipment,it is also of significance for WCDMA user equipment.In this paper,we focus on the research,design and implementation of initial multi-cell search algorithms in WCDMA.The concrete work and innovation are as follows:1)The WCDMA physical layer technology and the process of the three step cell search are studied.The traditional methods of the PSCH synchronization,SSCH synchronization and scrambling code confirmation are analyzed.Some optimization algorithms are presented for the PSC matched filter,the differential coherent accumulation,and the soft decoding of the RS codes.2)Initial multi-cell search scheme is proposed,which mainly contains three parts: PSCH synchronization,SSCH synchronization,and scramble code verification.In the design of the PSCH synchronization,the anti-noise performance of the different correlation value accumulations is analyzed,and the appropriate accumulation length of differential coherent is selected by simulation.Then the peak search algorithm is proposed to reduce the effect of multipath.In the SSCH synchronization,a new algorithm is proposed,which is based on the combination of differential coherent accumulation and soft decoding of RS codes,further more,the appropriate accumulation length is selected by simulation.In the scramble code verification,a verification method based on differential coherent accumulation and peak to average ratio is proposed,which shows good performance and easy to be implemented by hardware.Through a large number of simulations,the appropriate decision threshold is selected.3)The implementation scheme of initial multi-cell search based on DSP+FPGA is proposed.The hardware implementation of the system is designed in detail.The resource consumption of each module is given.Finally,the transplant of initial multi-cell search algorithm on a base station tester is presented.The proposed initial multi-cell search algorithms transplant on the base station tester is able to detect WCDMA cells with pilot Ec/Io beyond-20 d B,the search time is about 1s and the search consequence has a good stability,which shows advantages over similar products at abroad and meet the functional requirements of the base station test instrument for WCDMA system OTA test items.