The ITU standardized 5 groups of 3G radio access technologies.They are as follows :-
- IMT-DS :-The directr spread technology comprises wideband CDMA (W-CDMA) systems .This technology specified for UTRA-FDD and used by all european providers and the japanese NTT DoCoMo for 3G wide area services . To avoid complete confusion ITU'S name for the technology is IMT-DS ,ETSI called it UTRA -FDD in the UMTS context ,and the technology used is called W-CDMA .Today , standardization of this technology takes place in 3GPP .Details of it will be further provided.
- IMT-TC :- Intially ,this family member called time code ,contained only UTRA-TDD
systems which uses time-division CDMA (TD-CDMA).Latr on, the chinese proposal ,TD -synchronous CDMA (TD-SCDMA) was added.Both staandards have been combined and 3GPP fosters the development of this technology.It is unclear when and to what extent this technology will be introduced.The initial UMTS installation are based on W-CDMA.
- IMT-MC :- Cdma2000 is a mutli-carrier technology standardized by 3GPP2(third generation partnership project 2, 3GPP2 ,2002 ),which was formed shortly after 3GPP to represent the second main stream in 3G technology version cdma2000 EV-DO has been accepted as the 3G standard.
- IMT-SC :- The enhancement of the US TDMA systems, UWC-136, is single carrier technology originally promoted by the universal wireless communications consortium.It is now integrated into 3GPP efforts .This technology applies EDGE , among others, to enhance 136 standards.
- IMT-FT :- As frequency time technology ,an enhanced version of the cordless telephone standard DECT has also been selected for applications that do not require high mobility.ETSI is responsible for standardisation of DECT.
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