The objectives of this project are to design, develop, test and trial new service extensions to BGAN to provide efficient delivery of IP-multicast traffic to mobile users via the Inmarsat-4 satellites.
The Phase 1 IP-multicast services have been designed to support a range of applications, including efficient content delivery such as streaming video and audio, and file delivery to large populations of users. The Phase 2 IP-multicast services will be designed to support interactive communications such as push-to-talk voice and collaborative workgroup data applications, as well as situational awareness applications, for instance in support of disaster-relief personnel.
The objectives of this project are to deploy both categories of services in a trial configuration during this programme.
There are a number of key issues had to be addressed during the programme:
These elements introduced challenges in terms of architecture design and interface definition. Furthermore, the real-time operation of the Radio Access Network proved complex and tedious to implement, but was successful in the end.
Paul Febvre, Inmarsat Satellite System Architect: "The BGAN Extension Phase Two IP-Multicast service is ground-breaking. Nothing of this kind has ever been created in the mobile satellite communications arena."
Chris Insall, Inmarsat Maritime Product Manager: "Multicasting will offer further advances in terms of efficient delivery to entire fleets, and a richer array of user content (including multimedia, news and sport). Seagoing vessels are very much used to the system of two-way radio, and developments for multicast stage two offer new, lower cost voice access on a push-to-talk basis."
Gary Colledge, Inmarsat Aeronautical Safety Services Manager: "This facility could be usefully used for aircraft fleet management (Airline Operational Communications) or for the delivery of significant weather information such as turbulence warnings at certain flight levels and localities and other regional notices."
Dale Irish, Inmarsat Government Services Project Manager: "With this new Netted Communications capability, any member can take the floor and all others within the closed group can participate in the call. This new capability for BGAN will complete the package of services and capabilities that are required to make BGAN the system of choice for communications-on-the-move in government circles."
The BGAN System is designed to deliver voice, Circuit Switched data and Packet Switched data services to mobile terminals. The Inmarsat-4 satellites allow the Packet Switched services to provide up to 512kb/s to individual mobile terminals. The Packet Switched services offer the ability to transfer IP data through individual connections (Packet Data Protocol Contexts), where each PDP Context has a dedicated QoS profile.
The IP-multicast service provides an extension to the Packet Switched services to support IP-multicast via one-many connections termed Multicast Bearer Contexts. This service includes the capability to setup QoS specifications for the multicast traffic. The IP-multicast service spans multiple spot-beams on the Inmarsat-4 satellites and supports interconnection with remotely managed and sourced content via VPNs.
The operation of the Phase 2 services involves the support of Netted Voice and interactive data applications, and requires the efficient transfer of IP-multicast traffic in both directions, as illustrated in Figure 1 below:
Figure 1: Netted Voice Service Concept
The Multicast Core Network is implemented as an adjunct to the existing Packet Switched Core Network, with the logical network architecture being represented in Figure 2 below:
Figure 2: Logical Network Architecture
The key attributes of this network are the separation of the Radio Access Network, responsible for managing radio resources, from the Core Network which Control-Plane/ User-Plane BGAN Multicast Service Node from the entities responsible for managing the services BMSC. The Satellite BMSC is principally concerned with controlling access by the Mobile Terminals (MTs) to the BGAN Multicast Services, while the User BMSC entities are responsible for controlling access to content and distributing this content reliably and securely to the Users of Terminal Equipment.
The project plan involves the parallel development of the following elements:
All development activities took place during 2007 and 2008, culminating in phased integration exercises during 2009. In preparation for future satellite trials, during 2010 all elements have been integrated into an end-end real-time Proof-of-Concept (PoC) system on the bench, including multicast-enabled BGAN terminals and collaborative tools applications.
In addition, the programme also involved the development and evaluation of Multi-User Detection technology (Space-Time DSP) for netted communications via omni-directional terminals.