(3) The Development and Agreement of the Basic Parameters of the

GSM System and the GSM MoU from Q4 1984 to Q3 1987

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In the autumn of 1984 France and Germany agreed to terminate the development of their planned analogue 900 MHz ‘interim’ system and committed themselves instead to introduce networks based on the system standardized by GSM. They informed GSM during the Plenary in November 84 about this agreement and their plans of trials for the most critical new elements of GSM: the digital radio transmission and low bit rate speech coding (GSM 76/84). This information triggered experimental programs in several countries. GSM planned later a comparative evaluation to be carried out at the end of 1986. This led to very serious efforts to explore advanced technical solutions for the suitability in GSM.

During this phase analogue 900 MHz systems were put in service in the Nordic countries and UK. This showed clearly the need that the new GSM system needed to be in most aspects at least equal, but superior in several aspects to analogue ‘interim’ systems. This matter was regularly addressed by the UK and some others (e.g. efforts in regard of viability of hand portables).

The work in this period Q4 1984 to Q2 1987 was very intensive. It turned out that the original idea that GSM should just do the project management and rely on the work of other groups did not function. Hence GSM had to take on more and more tasks. Several permanent Working Parties who met independently from Plenary and a Permanent Nucleus were created. A structure for the GSM Recommendations and an action plan for their completion were created (GSM 23/86).

GSM developed a concept for the services (GSM 28/85 rev. 2). The system architecture including the definition of the system elements their interfaces and message flows were developed. Serious technical work was done on the radio subsystem in preparing the trials, their evaluation and conclusions. Also the work on low bit rate speech coding was very intensive. A complete architecture for security including authentication and encryption was developed. The use of SIM was agreed.

Principles for type approval, licensing of mobile stations and free circulation were developed. A concept for charging and accounting in international roaming was proposed and accepted. This work took place in GSM WP1 with input mainly from Germany. Result was a series of recommendations which were approved by GSM after consultation of other CEPT groups. Several were later transferred to GSM MoU groups.

The summit of this period was the GSM Plenary in Madeira in February 1987. There the most critical issue was the selection of the basic parameters of the radio subsystem. After an intensive debate, it was possible to find a full agreement that the GSM system should use digital technology on the radio path. But it was not possible to select a multiple access technology unanimously. However it was possible to agree working assumptions for a narrow band TDMA solution which allowed the continuation of the technical work (GSM 46/87 and 41/87). Based on a proposal of France, slow frequency hopping was included, but only as an operator’s option. The hopping capability was thus mandatory for mobile stations and optional for the network infrastructure. Based on the technical work done in the speech coding group it was also possible to agree working assumptions for the GSM Full Rate Codec. These assumptions included the use of an RPE-LPC algorithm with the possible addition of LPT, as well as the use of speech activity detection to allow discontinuous transmission. Principles for non-voice services were also agreed.

The selection of the basic parameters of the radio subsystem required further discussions until May 87 which led to a change of the modulation to allow the use of a more efficient channel coding scheme.

This work phase resulted in May 1987 in a set of future proof technically and economically optimal basic parameters for the whole GSM system which was advanced but implementable by the state of technology in the late 80s/early 90s. This set of parameters was approved unanimously and provided a firm direction for the following specification phases.

In order to stabilize the situation long-term, Stephen Temple (UK) proposed to create a GSM Memorandum of Understanding (GSM MoU). The Signatories committed themselves to open GSM networks in their countries in 1991. They took the obligation to support the standardization and to solve the necessary operational and administrative/regulatory matters. The GSM MoU was signed in September 1987 by operators from 14 countries. This agreement provided a significantly increased credibility in the commercial seriousness of the effort. Thus it provided a stable framework for the development and implementation of GSM. It offered also a home for several documents which did not fit in the upcoming ETSI standardization environment.

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