Introduction
The Universal Mobile Telecommunications System (UMTS) has adopted direct sequence wide-band code-division multiple access (DS-WCDMA) as its primary air interface. It can offer dedicated data rates up to 2 Mb/s in the downlink (DL) and 384 kb/s in the uplink (UL) with the baselined release 99 (R99) of the Third Generation Partnership Project (3GPP) standard, or up to 14.4 Mb/s in the DL with the high-speed shared downlink access channel (HSPDA) supported in R5. In R6 it offers up to 5.76 Mb/s in the UL with its E-DCH channels. For additional information about the UMTS standard, readers are encouraged to look at the 3GPP standard [2].