Tài liệu GSM and UMTS (P5) doc

Chapter 5: Evolving the Services

and System Features to

Generation 2.5 by the GSM

Phase 21 Program

Section 1: The GSM Phase 21 Work in ETSI SMG

(1993–1996)

Philippe Dupuis1

5.1.1 The Invention of Phase 21

5.1.1.1 The Invention of the Phase 21 Concept

In 1992 SMG had to stop adding new items to the phase 2 work programme. It was never￾theless clear that there would be something after phase 2. Some proposed to call it ‘‘phase 3’’.

This would of course have later caused some confusion with third generation. But the actual

reason why SMG rejected this expression is that it would have suggested a phase 2/phase 3

transition similar to the phase 1/phase 2 transition, while it was thought that, for this further

evolution, one should aim at a full cross phase compatibility. It would not have been indeed

acceptable to impose a retrofit or upgrading to all networks each time a category of mobile

equipment with novel features is introduced to suit a particular market requirement. As

explained in Chapter 4 such a full cross phase compatibility required more complexity in

the mobile equipment but this was now feasible in most cases. Even in phase 2, a trend in this

direction existed with the decision to have mobile equipment with multiple encryption algo￾rithms or multiple speech codecs. The expression ‘‘phase 3’’ having been rejected different

periphrases were used such as ‘‘beyond phase 2’’, or ‘‘the further work programme’’. Then at

the beginning of 1993 PT12 invented the expression ‘‘phase 21’’ which was immediately

adopted without debate. It appeared for the first time in the meeting report of SMG#6 (Read￾ing, March 1993).

Phase 21 was considered to be open ended. Its objective was to allow GSM to adapt to new

1 The views expressed in this section are those of the author and do not necessarily reflect the views of his affiliation

entity.

GSM and UMTS: The Creation of Global Mobile Communication

Edited by Friedhelm Hillebrand

Copyright q 2001 John Wiley & Sons Ltd

ISBNs: 0-470-84322-5 (Hardback); 0-470-845546 (Electronic)

market requirements coming from users, operators or manufacturers and resulting from

growing users expectation or from the progress in microelectronics which, for instance,

makes it possible to introduce terminals with enhanced features and functionality.

In 1996 it was decided that phase 21 would be organised in annual releases. The objective

here was to maintain a full internal consistency of the GSM core specifications and test

specifications throughout the various stages of their evolution. At SMG#17 (Edinburgh,

January–February 1996) an ad hoc group composed of Ansgar Bergmann, Simon Pike,

Re´mi Thomas and Jonas Twingler made proposals in this direction2 which were agreed at

SMG#18 (Bonn, April 1996). The first release was the 1996 release.

5.1.1.2 The Content of Phase 21

Phase 21 in March 1993 was just an extension of phase 2.3 The phase 21 workplan

contained new supplementary services such as ‘‘Completion of calls to a busy subscriber’’,

‘‘Malicious Call Identification’’, ‘‘Compression of user data’’. One work item, ‘‘Three-Volt

technology SIM’’, was a consequence of the progress of microelectronics, as is explained

below. There was nothing really revolutionary even if other items were already more future

oriented such as ‘‘Extension to the SMS alphabet’’ because of the adoption of GSM in the

Arab countries, and an expected similar move in China. ‘‘Service to GSM handportable

Mobile Stations in fast trains’’ was also triggered by the growth in the use of GSM in Europe.

‘‘Operation of Dual Band GSM/DCS by a single operator ‘‘ was already a precursor of the

future work on dual-band operation. Finally there were other work items required by actors in

other areas, such as GSM-DECT interworking or the support of Universal Personal Tele￾communications (UPT). This last category of work items never resulted in market products as

eventually GSM networks themselves succeeded to serve the various underlying user require￾ments.

It is only at SMG#6 that a process was started through which phase 21 would acquire its

full dimension. It started with a document4 tabled by Nokia suggesting that we could evolve

GSM beyond what we had previously envisaged. This document was only 2 pages long and

entitled ‘‘GSM in a future competitive environment’’. When it was first circulated everybody

was puzzled by the title and read it. Several participants immediately expressed their

disagreement very loudly. The document was indeed putting in question all the mainstream

ideas about the following generation, or UMTS. It was for instance proposing to adopt

improved speech coding algorithms, to introduce higher bit rate data services, etc. Many

of the meeting participants therefore objected that what was proposed in the document

actually belonged to the third generation and said they were very much against transforming

GSM into a 2.5 generation system. Passionate discussions took place during the coffee

breaks. Eventually we had to agree that all this was making sense. When the document

came for discussion and was presented by Heikki Ahava it received significant support.

Following a course of action which had been taken in similar circumstances in the past it

was proposed to arrange an extraordinary meeting to discuss the matter further. I had a

different idea. I thought that what was needed was brain storming rather that quick decisions

and suggested to hold an open workshop to which we could invite experts from non-ETSI

74 GSM and UMTS: The Creation of Global Mobile Communication

2 Report of the ad hoc group on working procedures, TDoc SMG 173/96, January 1996.

3 The first phase 2 1 work plan was produced by PT12 for SMG#7 (June 1993), see Tdoc SMG 475/93 and 517/93. 4 GSM in a future competitive environment, TDoc SMG 234/93, March 1993.

companies. Nokia was put in charge of arranging that workshop in co-operation with the

SMG chairman. I remember reviewing with Heikki Ahava during the following coffee break

a list of possible topics and speakers on each of them and adding to the list the integration of

Intelligent Networks (IN) concepts in GSM.

5.1.1.3 The Helsinki Workshop in October 1993

The workshop on ‘‘GSM in a future competitive environment’’ took place on the 12–13

October 1993 in Helsinki. It attracted 64 participants including some from organisations

not belonging to ETSI. The report5 was submitted to SMG#9 (Nice, January 1994).

It is difficult to summarise the results as proposals addressing a large number of different

areas were discussed. Most of them were not entirely new. However, putting them together in

perspective gave a striking effect. It made it clear that it was possible to design an evolu￾tionary path from GSM to the next generation of mobile communications. This was indeed

what Nokia had in mind.6 They thought that the mobile communications industry, having

invested so much in GSM, could not one day abandon it to adopt an entirely new system, as

UMTS was then expected to be. The point was made that in other regions of the world more

consideration was given to an evolutionary approach. In this respect an interesting paper was

presented by Dr Tiedeman of Qualcomm. I had invited him because he had inspired in the

ITU a paper from Korea suggesting the association of Qualcomm’s CDMA radio technology

with the GSM platform. This could have been a part of another evolutionary path towards a

single world standard.

Looking at the different evolution areas I was impressed by the fact that different features

that we had thought of to materialise only in UMTS7 could be implemented in GSM, such as

high quality speech, the integration of IN concepts, the integration of satellite and terrestrial

mobile communications, etc.

On the first day a dinner was hosted by Sari Baldauf of Nokia whom we had met in similar

circumstances at a GSM dinner in Helsinki in 1988. Her belief in the success of GSM and the

growth of mobile communications was certainly an encouragement to all of us.

5.1.2 Major Phase 21 Work Areas

It is not easy to make a comprehensive presentation of the work done in 1993–1996 on phase

21. Work was undertaken on so many different items that it would be too long to list them all.

In many cases also the results materialised some time later. In this section we just give some

indication of some of the work areas which are representative of the diversity of the content of

phase 21 or of the general trend in GSM evolution.

5.1.2.1 3-Volt SIM

This is a typical example of a technology driven evolution. As the reader knows, the SIM is

one of the most interesting elements of GSM. It carries all user specific data and can be

inserted in any type of Mobile Equipment (ME).

Chapter 5: Evolving the Services and System Features to Generation 2.5 75

5 TDoc SMG 2/94

6 TDoc SMG 234/93

7 See Chapter 8, Section 1.