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Mobile Services Using SIP and 7DS

Mobile Services Using SIP and 7DS. Henning Schulzrinne Joint work with Jonathan Lennox, Maria Papadopouli, Jonathan Rosenberg, Sankaran Narayanan, Kundan Singh, Xiaotao Wu and other members of the IRT lab Columbia University August 2002. Outline. SIP as enabler of mobile services

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Mobile Services Using SIP and 7DS

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  1. Mobile Services Using SIP and 7DS Henning Schulzrinne Joint work with Jonathan Lennox, Maria Papadopouli, Jonathan Rosenberg, Sankaran Narayanan, Kundan Singh, Xiaotao Wu and other members of the IRT lab Columbia University August 2002

  2. Outline • SIP as enabler of mobile services • quick overview of SIP • terminal, service and session mobility • event notification • machine-to-machine communications • location-based services • Multimodal communications • 7DS

  3. SIP • IETF-standardized application-layer signaling protocol • SIP URIs: sip:alice@example.com, sips:bob@foo.net (TLS) • Uses Session Description Protocol (SDP) to describe multimedia streams • Syntax similar to HTTP and SMTP/RFC 2822 • methods, extensible header, opaque body • built-in mobility model: • registrars track end system location • proxies to provide known contact point • "soft handoff"  one identifier, multiple terminals • mid-call session renegotiation

  4. System model outbound proxy SIP trapezoid a@foo.com: 128.59.16.1 registrar

  5. a@foo.com: 128.59.16.1 SIP session setup INVITE INVITE sip:bob@biloxi.com SIP/2.0 Via: SIP/2.0/UDP pc33.atlanta.com ;branch=z9 Max-Forwards: 70 To: Bob <sip:bob@biloxi.com> From: Alice <sip:alice@atlanta.com> ;tag=1928301774 Call-ID: a84b4c76e66710@pc33.atlanta.com CSeq: 314159 INVITE Contact: <sip:alice@pc33.atlanta.com> Content-Type: application/sdp Content-Length: 142 REGISTER BYE

  6. SIP in 3GPP • 3GPP (and 3GGP.2) uses SIP as signaling protocol for Internet Multimedia Subsystem (IMS) • but mobile operator mentality: • regular SIP client may not work on 3G network • limited interworking with clients on wired side • lack of openness and transparency • trusted network model <> IETF: protect user from network (and other users)

  7. SIP design • Framework with three applications: • route messages to abstractly specified (user@domain) destination • possibly with multiple physical destinations • applications = • Establishing and controlling IP telephony and multimedia sessions • instant messaging • presence

  8. SIP transparency • Not Q.931/ISUP split  signaling messages and intent preserved by network • Transparency (D. Willis): • dialog (sequence number) • identity of user • header  new services without network knowledge • body  new session negotiation • topology  discovery, loop prevention • functional  new methods

  9. Event notification • Missing service glue: • network management • alarms – "water in level 2" • email alert • geographic proximity alert • "friend Alice is in the area" • see geopriv work in the IETF  location object with embedded security and privacy policy • media interaction  DVR • "start of show postponed by 30 minutes" • "semantic SMS" • can build services one-by-one  generic platform for quick service creation

  10. Event notification video process control temperature IR detector alarms audio 1000 100 10 1 0.1 0.01 event interval email polling SIP events RTP

  11. Controlling devices

  12. CINEMA • Integrated communications environment • multimedia: audio, video, shared applications, chat, … • call handling and routing • conferencing • unified messaging • control of networked devices • instant messaging and presence • Carrier (hosted) or enterprise environment • Integrated with existing PSTN environment

  13. CINEMA components Cisco 7960 MySQL sipconf rtspd user database LDAP server plug'n'sip RTSP conferencing media server server (MCU) wireless sipd 802.11b RTSP proxy/redirect server unified messaging server Pingtel sipum Nortel Cisco Meridian 2600 VoiceXML PBX server T1 T1 SIP sipvxml PhoneJack interface sipc SIP-H.323 converter sip-h323

  14. sip:john@cs.columbia.edu INVITE sip:john@cs.columbia.edu My owner’s SIP address is sip:john@cs.columbia.edu Help!!! (invoke sipc to call sip:john@cs.columbia.edu

  15. Device control Do sip:lamp@cs.columbia.edu SIP/2.0 ….. <Control> <Action>turn lamp on</Action> </Control> serial port

  16. Terminal mobility • Terminal moves to different network • usually, via mobile IPv4/6 • but requires home network support • not likely to work through firewalls • SIP can support limited terminal mobility: • pre-call redirection • mid-call re-INVITE (but not simultaneous moves) • not good for TCP applications – except with NATs

  17. Session mobility • Move existing session from one (logical) terminal to another • e.g., from 3G to 802.11 terminal to landline terminal • not IP mobility  maintain separate interfaces • use SIP REFER for transferring session

  18. Service mobility • Ability to transparently move services between devices  much more data than in GSM SIM • end-system call handling descriptions • address books • call logs • Solutions: • SyncML (with SIP event notification?) • SIP URI binding for configuration information  SIP BIND proposal

  19. Current SIP standardization activities • IM/presence infrastructure • authorization, buddy lists, presence publication, ... • authentication and anonymity • emergency calls and ETS • conferencing support

  20. Multimodal networking • "The term multimodal transport is often used loosely and interchangeably with the term intermodal transport. Both refer to the transport of goods through several modes of transport from origin to destination." (UN) • goods packaged in containers  packets and messages • Networking  combine different modes of data transport that maximize efficiency

  21. Multimodal networking • Speed, cost and ubiquity are the core variables • cf. pipelines, ships, planes, trucks • Traditional assumption of value of immediacy from PSTN  demise of Iridium

  22. Access modalities delay bandwidth (peak)

  23. Cost of networking

  24. New wireless modes • High upstream cost  caching • cf. early Internet (Australia) • expand reach by leveraging mobility • locality of data references • mobile Internet not for general research • Zipf distribution for multimedia content • newspapers • local information (maps, schedules, traffic, weather, tourist information)

  25. 2G/3G WLAN hotspot + cache Infostation access sharing 7DS A family of access points

  26. Our Approach Increase data availability by enabling devices to share resources • Information sharing • Message relaying • Bandwidth sharing • Self-organizing • No infrastructure • Exploit host mobility

  27. 7DS • Application • Zero infrastructure • Relay, search, share & disseminate information • Generalization of infostation • SporadicallyInternet connected • Coexistswith other data access methods • Communicates with peers via a wireless LAN • Power/energy constrained mobile nodes

  28. traffic, weather, maps, routes, gas station Examples of services using 7DS news WAN events in campus, pictures where is the closest Internet café ? pictures, measurements service location queries schedule info autonomous cache

  29. WLAN query WAN Host D data query Host A Information sharing with 7DS cache miss Host C WLAN cache hit data Host B Host A

  30. Power conservation communication enabled on off time Forwarding FW query query Host C Host A Host B time 7DS options Cooperation Server to client Peer to peer Querying active (periodic) passive

  31. 7DS cooperation • Server to client • only server acquires and shares data • fixed server • mobile server (taxi, bus) • peer-to-peer • all peers share data • either data of local interest • or "memory dump" (iPod = 10 GB disk) • incentives: • recover expensive 3G bandwidth costs  cooperative, currency • enhanced user environment

  32. Simulation environment pause time 50 s mobile user speed 0 .. 1.5 m/s host density 5 .. 25 hosts/km2 wireless coverage 230 m (H), 115 m (M), 57.5 m (L) ns-2 with CMU mobility, wireless extension & randway model querier wireless coverage dataholder randway model

  33. Dataholders (%) after 25' high transmission power P2P Mobile Info Server Fixed Info Server 2

  34. Average Delay (s) vs dataholders (%)peer-to-peer schemes high transmission power medium transmission power

  35. Fixed Info Serversimulation and analytical results high transmission power Probability a host will acquire data by time t follows 1-e-at

  36. Delay (s) vs. dataholders (%) Fixed info server one server in 2x2 high transmission power 4 servers in 2x2 medium transmission power

  37. WLAN messages Host A Message relaying with 7DS WAN Gateway WLAN Message relaying Host B Host A

  38. Messages (%) relayed after 25 min avg. # of buffered messages = 5 2

  39. 7DS Implementation "sports" proxy cache list of items 7DS peer HTTP GET • full-text content index with HTML parser • type index ("news", "sport", "map") • select according to age, size, origin • FAZ > SZ > AZ

  40. 7DS implementation • Initial Java implementation on laptop • Compaq Ipaq (Linux or WinCE) • Inhand Electronics ARM RISC board • Low power • PCMCIA slot for storage, network or GPS

  41. 7DS deployment ideas

  42. Conclusion • Mobility is more than mobile IP and RAN... • SIP as service enabler for mobile services • not necessarily mobile terminals • Multimodal networks for cost-efficient mobile data access

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