The main objective of the EMBRACE project is to develop a low cost broadband wireless access system and services based on the results obtained during LMDS-trials under the ACTS program. In particular, inputs from users and operators regarding present and future access capacity demands and requirements for availability and quality of service will be used. The system will operate in the 40.5-42.5 GHz (43.5 GHz) bands and can easily be adopted for operation in other bands in the millimetre frequency range, allocated for this type of services. However, the indoor user's terminal can be used for a wide range of frequencies above about 20 GHz, suitable for broadband applications. In providing a low-cost fixed radio access technology all the benefits of the current Information Technology revolution will be delivered without requiring any broadband cable systems.
The main goal is to develop a low cost radio access system for the mass market. This will be achieved through efficient utilisation of radio frequency bands and optimisation of transmission capacities for a variety of users and usage. A prototype will be developed using MPEG-2 in the downlink and an uplink using multiple frequency time division multiple access. Time division duplex will be studied as an alternative to the frequency division duplex, realised in the hardware prototype. Star and mesh network allowing for network capacity growth as business grows, will be studied. The access network shall inter-operate and multiplex effectively with other common networks. Solutions allowing for nomadic users and route diversity (switching between two or more sase stations) will be developed. Planning tools that take into account obstruction from the topography and man-made structures, the effects of atmospheric propagation conditions and the antenna radiation patterns, will be developed.
The project is based on the ACTS programme, which identified a need for improvement of return link in the access systems and coverage. The project consists of three main areas: access system, network interaction, and network availability and performance. The work covers a total solution for broadband access based on radio technology. The radio based solution will be designed to easily inter-operate with other broadband solutions, and the backbone infrastructure as well. Prototype systems will be developed and tested in real scenarios. The workgroup on "Access system" will concentrate on the topics from the last switching point to the users. This includes provision of a large variety of transmission capacities on demand and frequency efficient modulation and coding techniques based on chosen frequency and channel plans. The workgroup on "Network interconnection" will concentrate on topics on the "last switching point" interaction with other base stations, other access networks and backbone infrastructure.
Topologies such as star and mesh networks will be investigated in order to obtain an optimal solution, allowing for network capacity growth as business grows. The workgroup on "Network availability and performance" will focus on radio service coverage and performance. Efficient use of frequency and optimised channel planning are of crucial importance, in particular when traffic volume approaches system saturation. The workgroup will develop planning tools that take into account the characteristics of the available frequency bands, obstruction from the topography and by man-made structures, the effect of atmospheric propagation conditions and the antenna radiation patterns.
The outcome from the EMBRACE project will enhance European export potential through generating a growth industry. The project will concentrate on the 40.5 to 42.5 GHz (43.5 GHz) bands, but the access system planning tools will also be applicable to other bands above 20 GHz. Contributions will be sent to regulatory and standards bodies. It will also contribute in promoting the concepts of broadband wireless access in the discussions of the FP5 programme.
The project has achieved all major goals. All planned deliverables have been provided and appropriate dissemination has so far been done. EMBRACE has integrated the full experimental system on site and was demonstrated to the public at an international workshop arranged in Norway in 2002. Part of the system was demonstrated during IBC 2001 in Amsterdam. Management has performed as planned and management routines followed. The results form the basis for exploitation as indicated by the individual partners, and should have a significant impact on the development of broadband fixed wireless access systems, their deployment and equipment manufacturing. Broadband fixed wireless access (BFWA) system. The project has expressed a detailed view on system requirements for a broadband fixed radio access system that can become a mass-market product as well as provide a solution for small and medium business, home office and organisations. Prototype equipment for complete base stations and user stations based on an MF-TDMA access scheme and a DVB-S downlink for combined transport of TV and data has been built.
It all functioned very well. AccessFor the investigation of TDD versus FDD it has been concluded that TDD offers great advantages under operating conditions with individual traffic (not TV dominated traffic) of varying degree of asymmetry. It offers flexibility and increased capacity relative to FDD and the problems of interference can be solved. The burst demodulation is not as unfavourable as commonly assumed and equipment may be manufactured cheaper compared to FDD. An important part of a broadband radio access system is the medium access control (MAC). The project's views are applicable to the prototype experimental equipment as well as for the future system. An important point here is the ability of handling thousands for users per basic radio cell or base station. Work on multiplexing introduced possibilities for priority control and cost reduction. Synchronisation have been analysed in detail and extended to include the route diversity situation, and the improvements by the use of multiple input multiple output (MIMO) technology. Adaptive modulation and coding is an area leading to improved spectral efficiency for the individual traffic. Networking and interoperability Networking aspects, including IP-based traffic for the users, addressed to both reach the mass market with a low cost solution, as well as providing business users high availability. The interconnection network has been fully defined using multi-protocol label switching (MPLS). Performance measurements have been taken as well. The important idea of path diversity and "shadow flows" has been verified for improved availability and support nomadic users. A generalisation of the "shadow flow" principle has been made with particular reference to cellular systems.
Important bandwidth saving techniques as multicast and broadcast on demand have been analysed (Deliverable D14) including new efficient multicast software. Interoperability with GSM/UMTS/GPRS (Deliverable D4), cable networks and satellite has been studied. Satellite interoperability was demonstrated connecting the master cell in Norway with a remote user over satellite (DVB-RCS standard) at the IST Event in Copenhagen 2002. Service availability, coverage and utilisation.
A new cell-planning tool for BFWA networks has been developed. The tool incorporates innovative meta-heuristic optimisation methods (such as Tabu search), allows a number of optimisation criteria (including criteria based on financial models) and a wide range of network variables and constraints to be explored. A number of the output products required for commercial deployment have been included as well as test cases studied. Rain diversity data have been collected, and a general statistical rain diversity model developed for network planning purposes. Also, a hardware simulator for rain fading has been completed ready for use within the diversity system development and trials. A practical demonstration of countermeasures against distortion on the radio path caused by vegetation (tree) effects has been made using a diversity combiner. A study on the broadband service requirements, markets and constraints in Eastern Europe was carried out in the western part of Romania.
Funding SchemeCSC - Cost-sharing contracts
CF10 3XQ Cardiff
00040 Morena - Roma
OX11 0QX Chilton, Didcot
GU21 5RW Woking