GSM and UMTS (P10)

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) Chapter 10: Services and Services’ Capabilities Section 1: The Early Years up to the Completion of the First Set of Specifications for Tendering of Infrastructure (1982 to March 1988) Friedhelm Hillebrand1 10.1.1 Introduction This section reports about the early discussions in the 1882–1985 timeframe, the agreement on a service concept in February 1985 and the elaboration of the first set of specifications needed for tendering of infrastructure by the operators in early 1988. A well structured and future-proof portfolio of tele-, bearer and supplementary services was specified. The principles for charging and accounting of international roamers were agreed. Innovative solutions for mobile station licensing, circulation and type approval recommendations were developed. They needed to be implemented by national or interna-tional regulatory authorities. This intensive services’ work provided guidance to the technical work on radio, network and data aspects. During this period the culture of service-lead standardisation was developed in GSM. This was a major achievement in the GSM work, since it ensured market orientation. 10.1.2 Overall Guidance is Provided by the CEPT Mandate and the First GSM Action Plan of December 1982 The mandate of CEPT for the GSM work requests the ‘‘Harmonisation of the technical and operational characteristics of a public mobile communication system in the 900 MHz band’’.2 The first action plan prepared by the Nordic and Dutch PTTs was approved at GSM#1 in December 1982.3 It contained basic requirements. Those related to services were: 1 GSM Working Party 1 ‘‘Services Aspects’’ (WP1) was chaired by Martine Alvernhe (France Telecom) from February 1985 to April 1991 with great engagement. I was an active contributor and participant in the work of WP1 duringtheperiodtreatedinthissection.Theviewsexpressedinthismodulearethoseoftheauthoranddonotnecessarily reflecttheviewsofhisaffiliationentity.AllquotedGSMPlenarydocumentscanbefoundontheattachedCDROM.The quoted GSM WP1 documents are not copied on the CD ROM. They can be retrieved from the ETSI archive. 2 Quoted in GSM 2/82, see also GSM 1/82. 3 GSM 2/82. 264 GSM and UMTS: The Creation of Global Mobile Communication 10.1.2.1 Basic requirements for GSM services in the first action plan (December 1982)4: † ‘‘Mobile stations can be used in all participating countries, preferably all CEPT countries † It is expected that in addition to normal telephone traffic, other types of services (non- speech) will be required in the system. † ..state-of-the-art subscriber facilities at reasonable cost. † The services and facilities offered in the public switched telephone networks and the public data networks...should be available in the mobile system. † The system may also offer additional facilities (e.g. special barring functions, rerouting of calls and special message handling facilities). † It should be possible for mobile stations...to be used on board ships, as an extension of the land mobile service. † The system shall be capable of providing for portable (handheld) mobile stations, but the consequential impact on the system shall be assessed. † ..voice security...must be taken into account.’’ GSM#1 also discussed whether a harmonisation of the emerging analogue 900 MHz interim systems5 should be studied. It was concluded that this would not be reachable due to the necessary short implementation periods and the commitments made by the PTTs and that the work should be focussed on a new mobile communication system. This was an important decision on a viable work focus. 10.1.3 Discussions from the Beginning of 1983 to the End of 1984 (GSM#2–6) 10.1.3.1 Interactions with CEPT Working Group Services and Facilities CEPT working group services and facilities produced several versions of a report on mobile services. The report gave rise to many questions by GSM. Towards the end of 1984 GSM came to the conclusion that this dialogue would not lead to results, since the CEPT group services and facilities had too broad a scope and a lack of know-how in mobile communica-tion. It was agreed to make their own efforts in GSM and a special focus on services was agreed for GSM#7 in February/March 1985. 10.1.3.2 The ‘‘Coexistence Between Vehicle-borne and Hand-held Stations’’ The big theme of the period 1982–1985 was the ‘‘Coexistence of vehicle-borne and hand-held stations’’. This was a hot issue, since most mobile systems had a very limited capacity and used call duration limitations. No existing European system supported hand-helds. This existed only in the American AMPS.6 Several countries in Europe planned the support of hand-helds in analogue systems.7 In others, mainly in the centre of Europe, spectrum was much scarcer due to the large demand by the many large armed forces in cold war times. 4 GSM 2/82. 5 NMT-900 in the Nordic countries, TACS (an AMPS derivative) in the UK and later in Italy and Austria, later the planned Franco-German S900 system. 6 Advanced mobile phone system. 7 The Nordic countries planned the introduction of NMT900 mainly for this purpose. The UK planned the introduction of TACS (an AMPS derivative) with an integrated hand-held support. France and Germany planned a 900 MHz interim system IS900 which would also support hand-helds. Chapter 10: Services and Services’ Capabilities 265 Several delegates clearly proposed not to admit hand-helds. Should there be a sufficient demand, a separate system evolved from cordless systems working in another part of the spectrum should be developed. ‘‘... several people believe that the majority of the mobile stations will be hand-held portables.’’8 A special working party was set up during GSM#5 and 6. They produced an exhaustive study.9 It was realised that personal communication would be an important future demand. Issues like in-building coverage were studied. The fears on the negative effect of hand-helds on high-rise buildings and in aircraft on the spectrum re-use pattern and this network capacity were addressed. In the end ‘‘the meeting agreed that the GSM mandate (Doc 2/82) clearly states that hand-held stations should be catered for in the system.’’10 This was to my judgement a decision effected by exhaustion of the participants. But it opened the way to GSM as we know it today, where hardly any dedicated vehicle-borne stations exist any more. But the discussion continued for some time before it was formally closed (see paragraph 10.1.5.4.1) 10.1.3.3 Discussions on Other Issues Other service related issues which attracted substantial interest were market surveys, the discussion of traffic models and a comparative evaluation of the tariffs in existing systems which showed large differences in the charging criteria and charging levels.11 10.1.4 The First Concept for Services Agreed in February/March 1985 (GSM#7) 10.1.4.1 A Concept Proposal by Germany and France A major step forward in the definition of services was reached at GSM#7 (February/March 1985) in Oslo. Germany and France presented a input document12 which proposed to use the ISDN differentiation of tele-, bearer and supplementary services and to use the description method using attributes within the GSM framework. The document clearly stressed that radiotelephony would be the most important service.13 It proposed realistic quality of service targets (e.g. a delay which should not exceed 80–100 ms) and a low bitrate bearer capability (8–16 kbit/s) to support radio-telephony. A comprehensive list of supplementary services was given. A classification as E (essential, i.e. mandatory for all networks) and A (additional, i.e. optional) was proposed. 7 The Nordic countries planned the introduction of NMT900 mainly for this purpose. The UK planned the introduction of TACS (an AMPS derivative) with an integrated hand-held support. France and Germany planned a 900 MHz interim system IS900 which would also support hand-helds. 8 Report of GSM#4 in February/March 1984, pp. 3, 2.j. 9 GSM 58/84 rev. 1. 10 GSM#7 Report, Section 13, second last paragraph. 11 Details can be found in the meeting reports on the attached CD-ROM. 12 GSM Doc 19/85. 13 This was an implicit rejection of the ISDN concept of a universal integrated network equally suited for all services. 266 GSM and UMTS: The Creation of Global Mobile Communication The document contained an initial list of possible telematic and data services. These were tailored to the market needs and the possibilities in a GSM system. An overall target of the proposed data service concept was to recognise that GSM is not a mobile ISDN. There were strong proponents of this concept, who wanted to implement an ISDN channel structure (2B 1 D with 2 £ 64 kbit/s 1 16 kbit/s) on the radio interface. This would have severely deteriorated the spectrum efficiency and the system capacity. The discussions in GSM on speech coding had led to a vision of low bitrate speech codecs (about 16 kbit/s). The system architecture discussion had led to an emerging vision to use ISDN in the core network. The German/French input document was based on these assump-tions and proposed a rich data services portfolio, which respected the overall target that GSM must be optimised for telephony and offer attractive data services for the ‘‘mobile office’’. A range of circuit switched data services with rates of up to 9.6 kbit/s was envisaged, since this was the maximum possible on a single traffic channel. No packet switched services were proposed, since packet switching was not possible on the traffic channels of ISDN switches. Instead the concept of short message transmission was proposed. The application envi-saged was the following: GSM was seen at that time as a car telephone system (the discussion on the viability of hand portables in the same network was still ongoing). So a typical application scenario was a plumber or other technician doing some repair work in the custo-mers home could receive short messages in his car waiting in front of the home. Another scenario was to enable a user to receive a short notice while he was engaged in a call. It was envisaged to carry all short messages on signalling links of the system with low priority. This signalling network in an ISDN-type GSM core network and the signalling links on the radio network form essentially an embedded packet switching network in an ISDN. Therefore SMS can be seen as the first packet switched service in GSM. The length of the signalling packets on the GSM radio interface is shorter than in the ISDN in order to allow an efficient transmission over the radio channel with its difficult transmission quality. Therefore the length of short messages was limited. Initially 128 bytes were envisaged. The detailed work allowed it to be extended to 160 characters (seven bit coding). The document also proposed several types of mobile stations: vehicle-mounted stations, hand-held stations, combined vehicle-mounted and hand-held stations, mobile payphones and mobile PBX. The first draft of this document had been elaborated by me. Very valuable comments and contributions were received from Bernard Ghillebaert (France Telecom). The document was then agreed and presented as an input with source ‘‘Federal Republic of Germany and France’’. This was the first example of a series of co-ordinated input documents, where the lead could lie on either side. They were called ‘‘Ghillebrand-Documents’’ by Philippe Dupuis. The significance of such a contribution is not the level of innovation, but the provision of a viable market-oriented concept, which can be agreed in the standardisation group and can provide direction to the future work of the group. And these criteria were fulfilled by this contribution. 10.1.4.2 Proposals for Services by the Nordic Countries A list of basic functions and capabilities of the GSNM system was proposed by Denmark, Chapter 10: Services and Services’ Capabilities 267 Finland, Norway and Sweden.14 Access capabilities made up of a control and a traffic channel with 16 kbit/s were proposed. Services should be telephony and several data services. Network functions were mentioned. A catalogue of types of mobile stations (identical to 10.1.4.1) was added. A initial list of supplementary services to be performed by the network was proposed by Denmark, Finland, Norway and Sweden.15 It contained, e.g. † barring services † absent subscriber services † mailbox services † group services: closed user group, group calls, conference calls In addition services and functions implemented in mobile stations were proposed, e.g. † dialling functions: abbreviated dialling, number repetition † hands-free operation † barring of outgoing calls † prevention of unauthorised use This work was based on the ISDN definitions and experiences of NMT. 10.1.4.3 The first Agreement on a Concept for Services at GSM#7 (February/March 1985) During GSM#7 a new Working Party WP1 ‘‘Services’’ met and elaborated a document on ‘‘Services and facilities of the GSM System’’ which was endorsed by GSM16 based on the input documents mentioned in 10.1.4.1 and 10.1.4.2. The output document contains a refer-ence model for services, definitions of tele-, bearer and supplementary services, network connections and types of mobile stations. The reference model introduces Terminal Adaptor (TA) functions at the mobile station and an Interworking Unit (IWU) between the mobile and the fixed network. The diagram is shown in Figure 10.1.1. The annexes of the document contain lists of teleservices including the Short Message Service (SMS). SMS had three services: mobile originated, mobile terminated and point to multipoint. It foresaw a maximum message length of, e.g. 128 octets, and an interworking with a message handling systems. Several other non-voice teleservices were proposed. A comprehensive range of circuit switched bearer services with speeds up to 9600 bit/s was proposed. The significance of this document was, that it was the first consensus in the Groupe Special Mobile on the service concept. The document provided the first ‘‘permanent’’ definition of services which could be enhanced by WP1 ‘‘Services’’. It could be used by other groups, e.g. WP2 ‘‘Radio Aspects’’, WP3 ‘‘Network Aspects’’ or later WP4 ‘‘data’’. 10.1.5 The Work on Services Aspects from March 1985 to March 1988 This work was carried out in WP1 ‘‘Services Aspects’’. 14 GSM Doc 7/85. 15 GSM Doc 8/85. 16 GSM Doc 28/85 rev 2. ... - tailieumienphi.vn