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

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

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

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 2 nd 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

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

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

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

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

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

MIP Tunneling: IP-within-IP Encapsulation

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

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

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

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

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

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

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

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

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

Applications

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