DenMasBroto : Technology Make It Possible
Category : Cellular Theory
3G Specifications
2008-06-01 14:54:39 - by : admin
3G

As the 3G system is expected to be global, world-wide and generic, the specification bodies related are also global ones (see the following list). In addition to the specification bodies, the specification process includes co-operation of operators and manufacturers.
There are four international standardisation bodies acting as “generatorsâ€Â for 3G specification work:
ITU-T (International Telecommunication Union)
This organisation provides in practise all the telecommunication branch specifications that are official in nature. Hence, these form all the guidelines required by the manufacturers and country-specific authorities. ITU-T has finished its development process for IMT2000, International Mobile Telephone – 2000. IMT- 2000 represents a framework on how the network evolution from a second to a third generation mobile communication system shall take place. Even more important, different radio interface scenarios were outlined for 3G systems (see figure below).
IMT2000
Figure 1. IMT-2000 framework and resulting 3G standards
ETSI (European Telecommunication Standard Institute)
This organisational body has had a very strong role when GSM Specifications were developed and enhanced. ETSI is divided into workgroups named SMG (number),
and every workgroup has a specific area to develop. Because of the GSM background, ETSI is in a relatively dominant role in this specification work.
ARIB (Alliance of Radio Industries and Business)
ARIB conducts studies and R&D, establishes standards, provides consultation services for radio spectrum coordination, cooperates with other overseas
organizations and provides frequency change support services for the smooth introduction of digital terrestrial television broadcasting. These activities are conducted in cooperation with and/or with participation by telecommunication operators, broadcasters, radio equipment manufacturers and related
ANSI (American National Standard Institute)
ANSI is the American specification body that has issued a license for a subgroup to define telecommunication-related issues in that part of the world. Because of some
political points of view, ANSI’s role is relatively small as far as UMTS concerned. The ANSI subgroup is mainly concentrating on a competing 3G air interface
technology selection called cdma2000. In order to maintain globalisation and complete control of the UMTS specifications, a separate specification body called 3GPP (3rd Generation Partnership Project) was established to take care of the specification work in co-operation with the previously listed institutes. The outcome of the 3GPP work is a complete set of specifications defining the 3G network functionality, procedures, and service aspects.
3GPP
Figure 2. 3rd Generation Partnership Project (3GPP) – standardisation body for UMTS
Because there are some political desires involved, the issue is not as simple as described; global system means global business and this is why there has been a lot
of pressure to select or emphasise certain solutions more than others. This political debate actually delayed the specification work remarkably, and finally an organisation was established to take care of the harmonisation issues. This organisation, OHG (Operator Harmonisation Group) aims to find a common understanding concerning the global issues. The results of this organisation are used as inputs in 3GPP work as well as in 3G future implementations. The OHG made its maybe the most remarkable decision in April-May 1999, when it decided the common-for-all-variants code word (chip) rate in the 3G WCDMA air interface. This issue has a direct effect on the system capacity and implementation and it was maybe the biggest delaying factor concerning the UMTS specifications. The aim of the OHG work is to affect the specifications so that all radio access variants are compatible with all the variants meant for switching; this will ensure true globalisation for 3G systems. The first UMTS release was frozen in December 1999. This release is called UMTS Release 99. In UMTS Release 99, the specification body 3GPP concentrated on two main aspects:
• Inauguration of a new radio interface solution. A new 3G radio interface solution must use the radio interface resources more efficient than it is the case with 2G radio interface solution. In addition to that, it must be very flexible in terms of data rates to allow a wide range of applications to be served. The UMTS radio interface solutions are based on the multiple access principle CDMA. CDMA stands for Code Division Multiple Access. In UMTS Release 99, CDMA is applied on 5 MHz carrier frequency bands.
This is the reason, why in some areas of the world, UMTS is called Wideband CDMA (WCDMA). Two radio interface solutions were specified with UMTS Release 99: The FDD-mode combines CDMA with frequency division duplex, i.e. uplink and downlink transmission are realised on separate 5 MHz frequency carriers The TDD-mode combines CDMA with time division duplex, i.e. uplink and downlink are made available of the same 5 MHz frequency carrier, separated by time.
• Network evolution: GSM is nowadays the dominating mobile communications technology. In order to protect the investment of a large number of mobile operators, network evolution guarantees the re-use of the existing core network and service infrastructure in UMTS. This was archived in UMTS Release 99 by adopting an enhanced GSM core network solution for the UMTS core network. The next version of the 3GPP Specifications is Release 4, which was frozen March 2001, and Release 5, which was frozen in March/June 2002. In Release 4 and 5, the upgrades in the radio access and radio access network were minor. The main focus lay on the core network and the service infrastructure. UMTS Release 4 included a specification of the Multimedia Messaging Service (MMS), a new radio interface solution for China called low chip rate TDD mode (or TD-SCDMA). While in UMTS Release 4 the first steps toward a ‘3G All IP’ could be found, this was fully specified in UMTS Release 5, including the IP Multimedia Subsystem (IMS).

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