Cellular History

Work began on a European standard for digital cellular telephony in the European Conference of Postal and Telecommunication Administrations (CEPT) in the mid-1980s. The task was entrusted to a committee known as Groupe Spécial Mobile (GSM), aided by a 'permanent nucleus' of technical support personnel, based in Paris.

In 1992, the work was moved to ETSI and the technical committee renamed Special Mobile Group (SMG). The permanent nucleus moved to ETSI headquarters and was renamed Project Team (PT) 12, later Special Task Force (STF) 12 (it was sometimes informally referred to as PT-SMG). In order not to destabilize the development, the document numbering system created by CEPT GSM was retained, though the term 'Recommendation' which CEPT used (this term is still employed by the International Telecommunication Union, ITU) was phased out and replaced by 'Technical Specification' (TS).

GSM specifications

Over the last couple of years, the specifications for the first phase of the new system were completed, and were published by ETSI. These are listed in TS 01.01 (Phase 1). In fact, the 'Technical Specification' did not fit well with the deliverable types produced by ETSI at the time, and the specifications were published as a mixture of GSM Technical Specifications, GTSs (later Technical Specifications, TSs), European Telecommunication Standards, ETSs (later European Standards, ENs) and ETSI Technical Reports, ETRs (later Technical Reports, TRs).

Indeed, for some specifications, it was not unknown for the deliverable type to change when the document was revised. For this reason, when dealing with cellular deliverables, it was easier to refer to the GSM specification number rather than the ETSI deliverable number. However, a software tool is provided to convert from one to the other.

The Phase 1 specifications were used for trials of the GSM system ('GSM' had become a well-known term, but its original connotation was no longer relevant, so it was reborn as an abbreviation for Global System for Mobile communications). Results were fed back into the standardization process to produce a second phase. (See TS 01.01 (Phase 2)). This phase was widely implemented in commercial networks from the mid-1990s onwards, and work had already begun on a subsequent phase, with further improvements and enhancements.

Data communications

In fact, engineers were already looking beyond the 'second generation' (i.e. GSM) towards a 'third generation', which would employ a different radio access technology to give higher data rates (Earlier analogue technologies were considered to be 'first generation'). GSM had originally been developed purely for voice telephony, but a data capability had been added to cater for a sudden increase in dial-up modem use on fixed lines. A maximum data rate of 9600 bits per second was offered, which matched or indeed exceeded that available over fixed line modems at the time. However, by the mid-1990s, dial-up data rates had surpassed this, and the performance of GSM circuit-switched data connections was now perceived as inadequate. Since a third generation digital cellular system was now envisaged, SMG decided not to call the next phase of the GSM specifications Phase 3: this might have been confused with 3rd Generation. Instead, it was decided to use the term 'Phase 2+', and the specification set was completed in 1996.

GSM Releases

By this time, it was clear that a more or less annual release of specifications, each containing improvements and additional service features over its predecessor, was desirable. New developments could be standardized without destabilizing previous releases (although faults detected with the earlier specifications would continue to be fixed). The nomenclature of the phased releases was now changed: the specification sets were still referred to as 'Phase 2+' but a release year was added. In fact, the releases became known simply as R97, R98, and R99, and the original Phase 2+ became known as R96. The specification sets for all of these Releases are listed in the corresponding Releases of TS 01.01.

Short Message Service

The origin of the text messaging services in GSM lies in the historical development of telecommunication services, and SMS was created by a small group of persons. The work on the standardization of services and the technical realization was approved by the CEPT Groupe Spécial Mobile.

Text messaging was a known telecommunications service years before the development of GSM started in 1982. Proposals for text messaging as a service in GSM were made by Nordic, German and French operators, who were all co-operating in the task.

The Nordic operators focused their work on text messaging by using an access to a message handling system, a service similar to e-mail. This service was standardized by the GSM committee and led to a technical report on the technical realization of the access to Message Handling Systems.

The German and French operators focused their work on 'Short Message Transmission'. This service uses a dedicated service centre and transmits the text messages over existing signalling paths of the GSM telephony system on a lower priority basis. This transmission method obviously constrains the message to be short: the maximum length, initially estimated as 128 octets, later optimised to 160 characters, is still sufficiently long for most personal or professional purposes.

The first phase of work, from February 1985 to the end of 1986, saw the GSM committee specifying the service features of SMS, with most contributions coming from Germany and France. From 1987 onwards the technical realization of SMS was standardized in a small group called Drafting Group Message Handling. The first Chairman of this group and the editor of the key technical specification were provided by Norway (later replaced by the UK), and technical work was mostly provided by Finland, France, Norway, and the UK.  The first phase of the SMS specifications comprised items that included service definition, network architecture, topology and protocols, acknowledgement capabilities, functionality for alerting on messages waiting, time stamping and capabilities of identifying application protocols.

The further evolution of the SMS was standardized in the same small group, led by the UK (where the technical work was mostly provided by the UK).  Examples of enhancements from this period are automatic replacement of messages, so-called 'flash SMS' and voicemail icons, followed by colour and picture capabilities, and long SMS.

SMS has become a phenomenal success that has been a surprise to many both inside and outside the communications industry.

3rd Generation

In 1998, the ETSI General Assembly took the decision on the radio access technology for the third generation cellular technology: wideband code-division multiple access, W-CDMA, would be employed. A dramatic innovation was attempted: a partnership project was formed with other interested regional standards bodies, allowing a common system to be developed for Europe, Asia and North America. The Third Generation Partnership Project was born.

Since the 3GPP system was to be based on a new radio access technology (W-CDMA) but was to re-use so far as possible the functionality of mobile terminals and the existing core network signalling system, it meant that most of the technical specifications developed by SMG could be transferred to the control of 3GPP. ETSI SMG retained only the specifications relating to the GSM radio access technology.

However, over the course of the first year of existence of 3GPP, it became clear that GSM, with already several hundred millions of subscribers worldwide, would continue to develop (especially data rate enhancements such as GPRS and EDGE). Asian interest in GSM, which had initially been largely absent, was rekindled: if not for opening GSM technology networks, then at least for designing and manufacturing GSM terminals and network infrastructure equipment.

Thus in mid-2000, responsibility for the remaining technical specifications was transferred from ETSI to 3GPP (effectively sharing the copyright on the GSM radio access technology specifications amongst all the 3GPP Organizational Partners), and ETSI SMG was closed down. In fact, ETSI retained control of a handful of specifications which were used for European regulatory purposes, and these were transferred to a new technical committee, Mobile Specifications Group (MSG).

3GPP Technical Specification Group (TSG) RAN was (and remains) responsible for the UMTS radio access technology (UTRAN), and TSG GERAN was created to manage the specifications for the GSM / GPRS / EDGE technology. The other 3GPP TSGs are responsible for the remaining specifications, most of which are common to both technologies.

With the creation of 3GPP, a new range of specification numbers was adopted for the 3G set, many of which were common to the 2G set. A comparison can be made in the R99 lists of TS 01.01 (R99) (2G) and TS 21.101 (R99) (3G).

3GPP Releases

The R99 UTRAN specifications were developed in record time - they were stable enough for Japan to start deploying its third generation network in little more than a year after the creation of 3GPP. For certain reasons - not least the incorporation of the Chinese variant of TDD - it was considered that strictly annual releases were no longer desirable: that the period between releases might need to be varied more as a function of technical content of the system rather than mechanically according to the calendar.

Thus subsequent releases take their identity from the version number of their specification sets rather than from the year: Rel-4, Rel-5, Rel-6, etc. A summary of the new features of each new release of the system specifications can be found on the 3GPP site. For Release 4 onwards, the GERAN-based system specification list can be found in TS 41.101, whilst the UTRAN-based system specification list remains in TS 21.101.

Bibliography

Hillebrand, Friedhelm [ed]: 'GSM and UMTS; The creation of Global Mobile Communication', Wiley 2002, ISBN 0470 84332 5.