The wideband-CDMA (W-CDMA) specifications are the most ambitious and complex radio standards ever written. Thus it comes as no surprise that new features are being continuously added to improve W-CDMA system performance.

One of the most significant additions to the W-CDMA specifications is the incorporation of high speed downlink packet access (HSDPA). Standardization of this new technology began in 2002 in W-CDMA Release 5. HSDPA increases downlink peak data rates and packet data efficiency, making the system more competitive with other high data rate wireless technologies in use today, such as 1xEV-DO.

This application note discusses the major changes that HSDPA introduces in the W-CDMA physical and transport layers, including new link adaptation techniques and modifications to the structure of the physical channels, modulation, and coding.