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Broad-Band Satellite Networks -The Global IT Bridge

Broad-Band Satellite Networks -The Global IT Bridge

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Broad-Band Satellite Networks -The Global IT Bridge

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  1. Broad-Band Satellite Networks -The Global IT Bridge By Abbas Jamalipour In Proc. of the IEEE, Vol. 89, No.1 Presented by Tsoline Mikaelian November 26, 2002

  2. Overview • Evolution of Satellite Systems • Broad-band Satellite Networks - Wireless ATM (WATM) - Mobile IP (MIP) - QoS Requirements - Traffic Requirements - Applications

  3. Fixed Satellite Systems • Fixed => Geostationary satellite (GEO) • INTELSAT (1965), INMARSAT(1982) • Used for long distance telecommunication and broadcasting • Do not offer Personal Communication Services (PCS) - Long propagation delay - Long propagation loss - No coverage of high-latitude regions

  4. Mobile Satellite Systems • Use satellites on lower orbits (LEO, MEO) - Reduce transmission delay and transmitter power, can cover high-latitude regions => offer PCS - Complicated mobility management issues • Developed in parallel with 2nd generation terrestrial cellular systems - Only voice, fax, low bit rate data apps => Called Narrow-band satellite networks - Ex. Iridium, Globalstar • Provide mobility in a broader range - Coverage area, geographical coverage vs population coverage

  5. Broad-band Satellite Networks: Motivation • Service requirements changed: - High-data rate Internet-based apps - Multimedia services => Called Broad-band satellite networks • Complement existing wireless nets • Provide global access • Consider Integration of ATM and IP technologies into a satellite link

  6. Wireless ATM Networks (WATM) • Provides mobility-supported high-efficiency multimedia services • WATM has traditional wired ATM network as its backbone

  7. WATM Protocol Architecture • ATM Protocol needs modification to support mobility • Mobility management: - Location management - Handover management

  8. Wireless IP Networks: Mobile IP (MIP) • MIP: Provides macromobility in wireless IP networks, wireless access to Internet users • - Physical, data link layers: provided by cellular networks - Network, transport layers: modified to route packets correctly to mobile users • IP address: network prefix used to route datagrams But MIP has no logical network prefix • - Mobile node (MN) is given a virtual home network - Constant IP address assigned - Location information database maintained on home net

  9. MIP Packet Flow • Detect change of MN location • MN acquires new IP address (CoA) • Registration with HA: notify HA of new location • Data packets routed to default MN’s home • Tunneling: HA redelivers based on CoAs registered

  10. MIP Tunneling: IP-within-IP Encapsulation

  11. MIP and Broad-band Satellites • MIP is a starting point for implementing IP services over broad-band satellite link • Inefficiencies: - Registration with HA at every handover and waste of resources - Packet losses during handover - High data latency due to tunneling

  12. ATM-based Satellite Networks • Operate at Ka-band usually (30/20 Ghz uplink/downlink) • ~ 2 Mbps or higher data rates • Satellites may be considered as ATM nodes with onboard processing capabilities => Apply ATM-based algorithms • Satellites may have mutual connections via Inter-Satellite Links (ISL) • Communication between mobile and fixed terminals

  13. Global Connectivity in ATM Networks Directly connectable terminal: Contains a satellite Adaptation Unit (also includes all physical layer functionality)

  14. Global Connectivity in ATM Networks Satellite Processing: Mux/demux, coding/decoding, ATM switching

  15. Global Connectivity in ATM Networks Gateway Station: Connectivity between satellite and ground segments. Contains Interworking Unit (IWU)

  16. Global Connectivity in ATM Networks Ground Networks: Include PSTN, NB/BB ISDN, frame relay, Internet, public/private ATM, fixed user terminals can be connected to those

  17. Global Connectivity in ATM Networks Network Control Center (NCC): Overall control of satellite resources and operations: call routing, management, location update, handover, registration, authentication

  18. QoS Requirements • Main Parameters: Timeliness, bandwidth, reliability, perceived QoS based on application type, cost, security • QoS management techniques: - Static functions (definition of QoS, admission control, resource reservation) - Dynamic functions (measuring QoS, maintenance, adaptation) • Mobility => change of QoS => adapt • More sophisticated QoS management in mobile environment - Short loss of communication during handover - New point of attachment => resources + renegotiation - Blind spots unavoidable

  19. Traffic Requirements • Unavoidable delay and delay variation in mobile satellite networks => UBR, ABR for implementation of TCP/IP over ATM satellites • Integrate IP traffic into ATM mobile satellites => aggregate multiple IP flows onto a single VC (by QoS manager) • Wireless satellite link => high BER => develop new congestion control and traffic management mechanisms in TCP layer

  20. Applications

  21. Conclusion Integration of mobile satellite, ATM and IP technologies can connect all terrestrial high-speed networks and can provide global mobility to multimedia terminals