1. 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. 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. 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. 4 System model SIP trapezoid outbound proxy a@foo.com: 128.59.16.1 registrar

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

6. 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. 7 SIP design Framework with three applications: route messages to abstractly specified (user@domain) destinationuser@domain possibly with multiple physical destinations applications = Establishing and controlling IP telephony and multimedia sessions instant messaging presence

8. 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. 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. 10 Event notification 1001010.10.011000 event interval alarms IR detector temperature process control audio video email polling SIP events RTP

11. 11 Controlling devices

12. 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. 13 CINEMA components RTSP sipum Cisco 7960 sipvxml SIP rtspdsipconf LDAP server MySQL PhoneJack interface sipc T1 sipd media server RTSP SIP-H.323 converter messaging server unified server (MCU) user database conferencing sip-h323 VoiceXML server proxy/redirect server Cisco 2600 Pingtel wireless 802.11b PBX Meridian Nortel plug'n'sip

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

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

16. 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. 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. 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. 19 Current SIP standardization activities IM/presence infrastructure authorization, buddy lists, presence publication,... authentication and anonymity emergency calls and ETS conferencing support

20. 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. 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. 22 Access modalities highlow high7DS802.11 hotspots lowsatellite SMS? voice (2G, 2.5G) bandwidth (peak) delay

23. 23 Cost of networking Modality modespeed $/MB (= 1 minute of 64 kb/s videoconferencing or 1/3 MP3) OC-3P 155 Mb/s $0.0013 Australian DSL (512/128 kb/s) P 512/128 kb/s $0.018 GSM voiceC 8 kb/s $0.66-$1.70 HSCSDC 20 kb/s $2.06 GPRSP 25 kb/s $4-$10 IridiumC 10 kb/s $20 SMS (160 chars/message) P ? $62.50 Motient (BlackBerry) P 8 kb/s $133

24. 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. 25 A family of access points Infostation 2G/3G access sharing 7DS hotspot + cache WLAN

26. 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. 27 7DS Application Zero infrastructure Relay, search, share & disseminate information Generalization of infostation Sporadically Internet connected Coexists with other data access methods Communicates with peers via a wireless LAN Power/energy constrained mobile nodes

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

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

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

31. 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. 32 Simulation environment pause time 50 s mobile user speed 0.. 1.5 m/s host density 5.. 25 hosts/km 2 wireless coverage 230 m (H), 115 m (M), 57.5 m (L) ns-2 with CMU mobility, wireless extension & randway model dataholder querier randway model wireless coverage

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

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

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

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

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

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

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

40. 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. 41 7DS deployment ideas

42. 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