Two main classes of mobile service are considered namely UMTS and MBS. For these systems the five primary aims are:
- an air interface specification for personal communications
- sufficient 'radio spectrum' capacity
- fixed network; functions signalling systems and architecture to support this
- to provide technical inputs into CCIR, CCITT, ETSI
- to identify a viable transitionary route from pre- existing systems to UMTS and MBS.
Two main classes of mobile telecommunication service were investigated:
the universal mobile telecommunication system (VMTS);
mobile broadband systems (MBS).
These were 5 main considerations:
an air interface specification for personal communications;
radio spectrum capacity;
the fixed network and the signalling systems and architecture to support this;
providing technical inputs into Comite Consultatif International des Radiocommunications of ITU (CCIR), Comite Consultatif International Telegraphique et Telephonique of ITU (CCITT) and the European Telecommunications Standards Institute (ETSI);
identifying a viable transitionary route from preexisting systems to UMTS and MBS.
The research has led to results in the following areas:
Progress has been made with the UMTS Requirement Specification, the UMTS System Framework, System Description and the European Telecommunications Standard Institute Evolution documents.
The work in channel management has studied different aspects of the air interface. Multiple access methods based on code division multiple access (CDMA) and time division multiple access (TDMA) have been considered and evaluated, but with an emphasis on TDMA systems.
Modulation, equalization and coding:
The work has resulted in the determination of the maximum achievable bit rates in different environments and in the recommendation of modulation schemes, block structures and suitable coding schemes for data services and possibly signalling.
The work in the cellular coverage core area has focused on key techniques for the UMTS radio network (such as handovers, dynamic channel allocation, location registration, paging) as well as the modelling of both narrowband and wideband radiowave propagation characteristics.
Fixed network mobile functions:
Progress has been made in the areas of generic functional models, related information flow diagrams for call setup, location update and rou ting, requirements for key management, handover between environments, evaluation of network procedures, influence of new services such as multimedia services and distribution services, support of Universal Personal Telecommunications (UPT) and dimensioning rules for location areas, paging areas and local exchanges.
In support of the system group there are five specific 'core areas' which investigate the key aspects of third generation mobile systems namely: channel management; cellular coverage; modulation, equalisation and coding; fixed network; and mobile broadband systems. The systems group incorporates the most recent results achieved in the five core areas into the final systems group deliverables and the CFS D730. The project will be completed in June 1992.
The key issues are associated with the expected situation in the year 2000. This is perceived as being a multi- operator environment with the possibility of wide area roaming, interpolate handover and a vast increase in mobile originated and terminated calls (around 50% of all network accesses). This will be combined with an increased customer awareness of mobility and a demand for improving quality.
The impact of the above scenario has been assessed in terms of:
- the need to provide a common access in all environments
- increased signalling traffic due to mobility causing an order of magnitude increase in signalling capacity requirement
- the need for call accounting transfer, during a call, between operators and between countries
- data intensive architectures to cope with the functions of mobility in an efficient manner
- the need for improved user authentication and system security
- ease of new service addition and facility enhancement both in the air interface and the supporting network
- the potential for new, high bit rate, service
- improved service quality (eg speech quality, handover reliability and coverage)
- improved efficiency in the use of the available RF spectrum.
Progress has been made with respect to consolidation of the core area work, the UMTS Requirement Specification, the UMTS System Framework deliverable, the System Description document, the Evolution deliverable, and CFS D730. The group has contributed significantly to the work in ETSI CCITT and CCIR (TG 8/1).
The work in channel management has studied different aspects of the air interface. Multiple access methods based on CDMA and TDMA have been considered and evaluated, but with an emphasis on TDMA systems. Packet access schemes have been studied as a part of the TDMA solution and especially for data services with bursty traffic packet access appears to be a very attractive solution.
Modulation, Equalisation and Coding
The work in the modulation, equalisation and coding core area has resulted in the determination of the maximum achievable bit rates in different environments and in the recommendation of modulation schemes, block structures and suitable coding schemes for data services and possibly signalling. For comparing modulation schemes, a measure of relative spectrum efficiency, is used and has successfully been applied to compare various suggestions for block structures.
The work in the cellular coverage core area has focused on key techniques for the UMTS radio network (such as handover, dynamic channel allocation, location registration, paging) as well as the modelling of both narrowband and wideband radiowave propagation characteristics. Studies of handover strategies, especially in highway and city microcells and indoor/outdoor environments have revealed that forward handover has a great potential in a mixed cell system. Handover performance is also improved by the introduction of umbrella macrocells. Slow and medium-term dynamic channel assignment was studied in addition to interference-based short-term dynamic channel allocation. Functional models and information flow diagrams were developed for the handover system service, the distribution service, the road traffic information service, and the message handling service.
Fixed Network Mobile Functions
Progress in the fixed network mobile functions core area has been made in the areas of generic functional models, related information flow diagrams for call set-up, location update and routing, requirements for key management, handover between environments, evaluation of network procedures, influence of new services such as multimedia services and distribution services, support of UPT, and dimensioning rules for location areas, paging areas and local exchanges. Contributions for standardisation have been presented in the area of distributed databases to ETSI STC NA7 and in the area of fixed network mobile functions to ETSI RES ad-hoc UMTS.
Mobile Broadband Systems
This core area of the project is concerned with B-ISDN type services to be carried on the IBC network which should be extended to the mobile sector and which are not covered by UMTS. Generally this is expected to be for bit rates greater than 2 Mbit/s without precluding lower bit rates. Experimental propagation measurements have been conducted at 39 GHz and 60 GHz and a representative channel model is being developed.
This project expects to provide the framework for the work to be carried out in RACE Phase II.
SO51 0ZN Romsey