1. VoIP and IP conferencing over satellites Workshop on VoIP Technology: Research and Standards for reliable applications PIMRC 08, Cannes France 15 September 2008 Dr. Haitham Cruickshank University of Surrey, UK

2.  Today there is an exponential growth of IP conversational traffic.  Satellite networks can offer an optimal support for Multimedia Multiparty Conferencing and IP Multicasting Services over large geographical areas. The new emerging satellites with multiple spot beams and On-Board Processing (OBP) will have new capabilities of dynamically routing information between various spot beams  However, there is a need to address the multicast routing, QoS and distribution models for conferencing media (audio and video) over satellites Introduction - 1

3.  QoS and multicast requirements for IP conferencing were addressed in an EU project called ICEBERGS (led by Thales-Alenia Space Italy).  ICEBERGS focused on the efficient configuration intra- domain and inter-domain multicast routing. The architecture consists of the following set of Internet protocols: The intra-domain protocol used here is the Protocol Independent Multicast-Sparse Mode (PIM-SM): Each domain uses its own Rendezvous Point (RP) (one or more). A source located in a given domain registers with an RP of that domain. RPs belonging to different domains exchange information related to the existence of active sources, by means of the Multicast Source Discovery Protocol (MSDP). An extension of the classical unicast inter-domain routing protocol, BGP is used for inter-domain routing: Multiprotocol Border Gateway Protocol (MBGP). MBGP cooperates with MSDP in order to provide efficient multicast tree construction between various domains. Introduction - 2

4.  There is a trade off between the large bandwidth requirements of real-time multimedia conference and expensive satellite bandwidth cost. Therefore there is a need for efficient mixing and distributing conference media (such as audio and video).  A hybrid model is used, taking advantage of the MultiPoint Control Unit (MCU) in H.323 architecture. MCUs have two main functionalities Capability to perform audio mixing and video switching on the video-conference streaming flow Inter-working between the unicast and multicast IP subset  Another aspect of conferencing is signalling Signalling concerns creation, user invitation and termination of conference sessions. SIP messages are used by the MCUs to initiate the satellite connectivity by using RSVP message with the satellite terminal. Conferencing media models

5. IP conferencing over satellite architecture

6.  A hybrid IntServ-DiffServ approach is used for mixed satellite and terrestrial networks. Strict QoS assurances are provided by implementing the RSVP protocol in the satellite network whereas in the core portion of the terrestrial Internet network, where scalability is a stringent requirement, the scalable DiffServ model is adopted together with QUASIMODO  The Quality of Service-Aware Multicasting over DiffServ and Overlay Networks (QUASIMODO) built on top of existing multicast protocols such as PIM-SM. It includes two ideas: Resource availability along a new QoS path is verified via a probe-based approach. QoS is maintained by marking replicated packets with a special DiffServ Code Point (DSCP) value before forwarding them on the QoS path. QoS implementation in IP multicast environment

7. QoS performance measurement setup

8. Quasimodo performance against best effort delay

9. Conclusions  A suitable architecture for IP videoconference system is proposed with IP multicast architecture, multiple MCUs, QoS provision technique based on QUASIMODO: A multicast solution is proposed to support multiparty multicast multimedia IP conference over next generation OBP GEO satellite. This solution consists of three multicast protocols: PIM-SM, MSDP and MBGP RSVP is used as a triggering mechanism in the satellite channel establishment in ICEBERGS. For the terrestrial part, PIM-SM join message triggers the QUASIMODO protocol.  The demo results show QUASIMODO provides good improvement in QoS for IP conferencing in terms of reduced delay