Wideband Direct Spread CDMA technique. It is a major standard/specification for third-generation (3G) cellular network. WCDMA is designed to offer high data rate to support 3G mobile functionalities, such as Internet surfing, video download/upload, and interactive real-time mobile applications. WCDMA was selected as the air interface for UMTS, the 3G data part of GSM. Attempts were made to unify WCDMA (3GPP) and CDMA-1X (3GPP2) standards in order to provide a single framework.
Published in Chapter:
Advances of Radio Interface in WCDMA Systems
Ju Wang (Virginia Commonwealth University, USA) and Jonathan C.L. Liu (University of Florida, USA)
Copyright: © 2009
|Pages: 6
DOI: 10.4018/978-1-60566-014-1.ch002
Abstract
Recent years have witnessed the rapid progress in handheld devices. This has resulted in a growing number of mobile phones or PDAs that have a built-in camera to record still pictures or live videos. Encouraged by the success of second generation cellular wireless networks, researchers are now pushing the 3G standard to support a seamless integration of multimedia data services. One of the main products is WCDMA (Holma & Toskala, 2001), short for wideband code division multiple access. WCDMA networks have 80 million subscribers in 46 countries at the time of this writing. WCDMA can be viewed as a successor of the 2G CDMA system. In fact, many WCDMA technologies can be traced back to the 2G CDMA system. However, WCDMA air interface is specifically designed with envision to support real time multimedia services. To name some highlights, WCDMA: • Supports both packet-switched and circuitswitched data services. Mobile best-effort data services, such as Web surfing and file downloads, are available through packet service. • Has more bandwidth allocated for downlink and uplink than the 2G systems. It uses a 5 MHz wide radio signal and a chip rate of 3.84 mcps, which is about three times higher than CDMA2000. • Support a downlink data rate of 384 kbps for wide area coverage and up to 2 Mbps for hot-spot areas, which is sufficient for most existing packet-data applications. WCDMA Release 5 (Erricson, 2004) adopts HSDPA (High-speed downlink packet access), which increases peak data rates to 14 Mbps in the downlink. To achieve high data rate, WCDMA uses several new radio interface technologies, including (1) shared channel transmission, (2) higher-order modulation, (3) fast link adaptation, (4) fast scheduling, and (5) hybrid automatic-repeat-request (HARQ). These technologies have been successfully used in the downlink HSDPA, and will be used in upcoming improved uplink radio interface in the future. The rest of this article will explain the key components of the radio interface in WCDMA.