Issues in Time and Frequency Synchronization in WCDMA System Mridula S. Korde Department of Electronics Engineering Shri Ramdeobaba College of Engineering & Management Nagpur, India mridula_korde@yahoo.com Abhay S. Gandhi Department of Electronics Engineering Visvesarayya National Institute of Technology Nagpur, India abhay4083@yahoo.co.in Abstract— 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. Keywords- WCDMA,cell search,synchronization I. INTRODUCTION There has been a tremendous growth in wireless communication technology over the past decade. The significant increase in subscribers and traffic, new bandwidth consuming applications such as gaming, music down loading and video streaming will place new demands on capacity. The answer to the capacity demand is the provision of new spectrum and the development of a technology – Wideband CDMA. The Wideband CDMA radio interface is chosen by ETSI as the basic radio access technology for the universal mobile telecommunications systems (UMTS). II. 3 G STANDARDS 3G Systems are intended to provide a global mobility with wide range of services including telephony, paging, messaging, internet and broadband data. International Telecommunication Union (ITU) started the process of defining the standard for third generation systems, referred to as International Mobile Telecommunications 2000 (IMT-2000). In Europe, European Telecommunications Standards Institute (ETSI) was responsible of UMTS standardization process. The aim of IMT-2000 is to harmonize worldwide 3G systems to provide global roaming. Five different standards are grouped together under the IMT-2000 label: W-CDMA, CDMA2000, TD-CDMA/TD-SCDMA, DECT, and UWC- 136. Of these five standards, only three allow full network coverage over macro cells, micro cells and pico cells and can thus be considered as full 3G solutions: W- CDMA, CDMA2000, and TD-SCDMA. III. CODE DIVISION MULTIPLE ACCESS AND WCDMA Code Division Multiple Access (CDMA) is a multiple access technology where the users are separated by unique codes, which means that all users can use the same frequency and transmit at the same time. With the fast development in signal processing, it has become feasible to use the technology for wireless communication, also referred to as WCDMA and CDMA2000. In cdmaOne and CDMA2000, a 1.25 MHz wide radio signal is multiplied by a spreading signal (which is a pseudo-noise code sequence) with a higher rate than the data rate of the message. The resultant signal appears as seemingly random, but if the intended recipient has the right code, this process is reversed and the original signal is extracted. Use of unique codes means that the same frequency is repeated in all cells, which is commonly referred to as a frequency re-use of 1. WCDMA is a step further in the CDMA technology. A. WCDMA (Wideband Code Division Multiple Access) W-CDMA (Wideband Code Division Multiple Access) is a wideband spread-spectrum channel access method that utilizes the direct-sequence spread spectrum method of asynchronous code division multiple access to achieve higher speeds and support more users compared to 2012 International Conference on Advances in Mobile Network, Communication and Its Applications 978-0-7695-4720-6/12 $26.00 © 2012 IEEE DOI 10.1109/MNCApps.2012.8 11