The aim of the BRAHMS project is to define and develop a universal user access interface for Broadband Satellite Multimedia services, which is open to different satellite system implementations. The motivation is to open up and expand the market for satellite user terminals by harmonising the majority of common satellite access network functions whilst allowing flexibility for optimised or proprietary air interfaces to satellite systems. The targeted end-user markets for Broadband Multimedia Satellite Systems (BMSS) are mainly those where high speed access is at a premium. Two-way transmission for Direct-to-Office or Direct-to-Home multimedia services will be addressed with bit rates up to 150 Mb/s (forward link) and 20 Mb/s (return), providing the end user with an effective bandwidth that improves upon state-of-art multimedia systems
The objective of BRAHMS is to define a universal user access interface for Broadband Satellite Multimedia Services which is open to different satellite system implementations, including GEO and LEO constellations.
The rationale for this approach is to open up and expand the market for satellite user terminals, and for satellite systems in general, by harmonising the majority of common satellite access network functions whilst allowing flexibility for optimised or proprietary air interfaces to satellite systems. This commonality and flexibility (e.g. for frequency, access type, orbit) is obtained by separating physically-related functions from common service and access functions.
The concept is dubbed the Broadband Multimedia Satellite System (BMSS) and aims to address a range of multimedia user groups with data rate requirements up to 150Mb/s. This BMSS approach is seen as a vehicle for convergence between fixed and mobile multimedia networks towards the Global Multimedia Mobility (GMM) architecture, by merging service functions derived from the UMTS/IMT 2000 and from fixed broadband access.
The use of IP-based satellite transmission will be considered as a solution to convergence towards seamless broadband service provision.
To achieve the project goals the work is divided into three main phases:
Design & prototyping of key equipment
Validation of significant BMSS features through a network testbed.
The BMSS approach is seen as a vehicle for convergence between fixed and mobile multimedia networks towards the Global Multimedia Mobility (GMM) architecture, by merging service functions derived from the UMTS/IMT-2000 and from fixed broadband access.
The separation of higher layer radio-technology independent (RTI) access network functions which "hide" the lower layer dependent (RTD) functions from the user and the core network, is a key strategy for this convergence and is known as the Generic Radio Access Network (GRAN). The common RTI layers in the user and hub stations in access networks will aim to support a full range of multimedia services (i.e. broadband and Internet) and connection to alternative customer premises and core networks. Different RTD layers are intended for different satellite systems (e.g. LEO, GEO constellations) and different radio access schemes (e.g. TDMA/FDMA/CDMA, frequencies) within the access network and will each support an extensive but different subset of the services of the RTI layer, suited to particular markets.
This architecture will also enable easier inter-working of user terminals between alternative satellite (and terrestrial) networks, including roaming.
Moreover, the use of "pure" IP transport will be considered in terms of its:
ability to ease inter-working and speed convergence towards seamless broadband service provision
practicality in the satellite access network
compatibility with the RTI/RTD approach.
The main challenges are firstly to define the attributes of a common RTI layer which includes all service functions (e.g. IP transport, etc.) compatible with a range of RTD layers, and secondly a common interface between RTI and RTD layers (in both the user terminal and the hub station).
The RTI part will include all end-to-end service control functions with inter-working towards core networks such as B-ISDN and Internet. Mobility will be included for user roaming and Intelligent Network (IN) functionality such as Virtual Home Environment (VHE) in which the user's desired operating system environment is downloaded from a service provider, allowing services to be tailored flexibly to each end-user. This part will also address inter-working between the BMSS and other fixed/mobile terrestrial/satellite segments, and thus issues of fixed-mobile and satellite-terrestrial convergence.
The RTD layer will not be unique but examples compatible with high speed multimedia services will be emulated based on Ku and Ka band GEO and LEO satellites and with selected access schemes (e.g. TDMA, FDMA). Different forward/return link combinations are envisaged according to interactivity requirements for two main user types to be addressed: Direct-to-Office (DtO) and Direct-to-Home (DtH) multimedia services.
A "Network Adaptation Layer" function at the user terminal side will perform service adaptation in order to match the required features of an application service to the QoS available from a selected access network.
QoS and seamless broadband service provision (both IP and real-time)
Applicability of RTI/RTD approach to other existing and planned systems
Degree of separation between RTI and RTD layers with different access technology
Validation of key BMSS features through development and testing of applications on a prototype testbed.
The principal impacts in the research field will be:
contributions to standards for universal access to broadband multimedia services.
flexible, re-configurable platform assessment of broadband multimedia satellite systems.
Wider impacts will be:
provision of reference points to allow manufacturers, service providers and operators to gauge their future plans for Broadband Multimedia Services.
preparation of industrial choices for advanced satellite Broadband Multimedia Systems.
Funding SchemeCSC - Cost-sharing contracts
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