WIDE-BAND DS-CDMA FOR NEXT-GENERATION MOBILE COMMUNICATIONS-SYSTEMS

Wideband wireless access based on direct sequence code division multip le access aimed at third-generation mobile communications systems is r eviewed. W-CDMA is designed to flexibly offer wideband services which cannot be provided by present cellular systems, with various data rate s as high as 2 Mb/s. The important concept of W-CDMA is the introducti on of intercell asynchronous operation and the pilot channel associate d with individual data channels. Intercell asynchronous operation faci litates continuous system deployment from outdoors to indoors. Other t echnical features of W-CDMA include fast cell search under intercell a synchronous operation, fast transmit power control, coherent spreading code tracking, a coherent Rake receiver, orthogonal multispreading fa ctor forward link, and variable-rate transmission with blind rate dete ction. The introduction of the data-channel-associated pilot channel a llows W-CDMA to support interference cancellation and adaptive antenna array techniques that can significantly increase the link capacity an d coverage. This article presents radio link performance evaluated by computer simulation. Field experiment radio link performance results a re also presented.