Issues in Time and Frequency Synchronization in WCDMA System

In the wireless world, the demand for advanced information services is growing. Voice and low-rate data services are insufficient in a world where high-speed internet access is taken for granted. The trend is toward global information networks that offer flexible multimedia information services to users on demand, anywhere, anytime. The third-generation (3G) mobile communication (International Mobile Telecommunications-2000, IMT-2000) systems are being developed to support a wide range of bearer services with low to high data rates Wideband CDMA (W-CDMA), proposed by 3GPP (Third Generation Partnership Project), is one of the major proposals for ITU IMT-2000 RTT (Radio Transmission Technology) standards. In a WCDMA cellular system, the process of the mobile station searching for a cell and achieving code and time synchronization to its downlink scrambling code is referred to as cell search. Cell search is performed in three scenarios: initial cell search when a mobile station is switched on, idle mode search when inactive, and active mode search during a call. The latter two are also called target cell search. This paper presents various issues in time and frequency synchronization for initial cell search scenarios for the Wideband CDMA (W-CDMA) standard.