Wcdma System Uplink Spreading Code Synchronization Algorithm

In WCDMA system which uses direct sequence to spread spectrum, the spread spectrum code (PN code) phase of the receiver must be synchronized with that of the received signal precisely to despread and demodulate the signal correctly. Multipath channel exists in the mobile communication environment for the radio signal reflection by obstacles between transmitters and receivers. By using the autocorrelation of the spread sprectrum code, RAKE receiver can process received signals and therefore multipath components can be resolvable. Synchronization technique of spread spectrum code is utilized in two stages. Multipath searcher coarsely estimates the PN code phase and code tracking confirm the PN code phase precisely. Because multipath searcher and code tracking are accomplished on the hardware, the complexity of the circuit should be concerned. The design of PN code synchronization should find a trade-off between the performance and the complexity of the reciever.In this paper, the PN code synchronization technique in spread spectrum communication is introduced. And the PN code synchronization scheme adequate for the WCDMA uplink is presented and combined with finger management, channel estimation and MRC algorithms to complete the RAKE receiver scheme. Simulations on Pd/Pf and Pd/EbNo show the scheme has good preformance and meets the requirement of WCDMA uplink in 3GPP protocols.