UMTS IMT-2000 BASED ON WIDE-BAND CDMA

The UMTS terrestrial radio access is based on wideband 4.096 Mchip/s D S-CDMA technology. UTRA will be connected to an evolved GSM core netwo rk for both circuit and packet services. A merge between ETSI/Europe a nd ARIB/Japan based on W-CDMA, a GSM core network, and a common freque ncy allocation according to the ITU Recommendation of 2 GHz makes a gl obal IMT-2000 standard feasible. UTRA based on W-CDMA fully supports t he UMTS/IMT-2000 requirements (e.g.. support of 384 kb/s for wide-area coverage and 2 Mb/s for local coverage). Furthermore, the air interfa ce has flexible support of mixed services, variable-rate services, and an efficient packet mode. Key W-CDMA features also include improved b asic capacity/coverage performance compared to second-generation syste ms, full support of adaptive antenna arrays, support of hierarchical c ell structures with interfrequency handover, and support of asynchrono us inter-base-station operation. There have been no constraints due to strong requirements for backward compatibility with second-generation systems. This has facilitated a high degree of flexibility and a futu re-proof air interface. Extensive evaluations by means of simulations and field trials have been carried out by a number of companies, and f ull system tests are ongoing. Consequently, W-CDMA technology can now be regarded as a mature technology, ready to provide the basis for UMT S/IMT-2000.