1. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 1 Presence in the IP Multimedia Subsystem Happenhofer Marco June 26, 2008

2. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 2 Switched of your mobile phone? Will only prevent ringing of your phone, but  it will not prevent the caller to call you and  the caller will not know why he did not reach you

3. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 3 Imaging: “You could inform your friends and buddies, if you are going to accept call now.”  Would it be useful?  Would you use this service?  And, would you pay for it ?

4. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 4 Agenda  Meaning of Presence  Architecture  Presence in SIP  Presence in IMS  Business Model and relevance to LTE  Conclusions

5. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 5 Agenda  Meaning of Presence  Architecture  Presence in SIP  Presence in IMS  Business Model and relevance to LTE  Conclusions

6. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 6 Definition of Presence “A presence [..] system allows users to subscribe to each other and be notified of changes in state, [..].”[IETF] „In computer and telecommunications networks, presence information is a status indicator that conveys ability and willingness of a potential communication partner - for example a user to communicate.“ Wikipedia[en] “Presence describes the social willingness and technical possibilities (of a subscriber) to accept a connection.” “A Presence Service is a software system whose role is to collect and disseminate presence information, subject to a wide variety of controls.“ OMA

7. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 7 History  Presence was no topic in plain old telephone systems, because no display possibilities and analogue processing  With Internet chats Presence become popular, because computer could display this state and manage buddy lists (e.g. ICQ)  Skype as first telephone system uses also Presence to display the current state of the buddies  IETF specified also mechanisms to convey presence information

8. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 8 Standardisation bodies  IETF (Internet Engineering Task Force) specifies IP, SIP, PIDF, XCAP, etc. mostly technologies used by presence. www.ietf.org  3GPP (3th Generation Partnership Project) specifies the practical implementation of IMS. www.3gpp.org  OMA (Open Mobile Alliance) concentrates on services and enablers. www.oma.org

9. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 9 Agenda  Meaning of Presence  Architecture  Presence in SIP  Presence in IMS  Business Model and relevance to LTE  Conclusions

10. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 10 What information carries Presence Presence describes the state of a buddy binary with „online“ or „offline“. in a homogen communication system

11. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 11 What information could be carried by Presence  Presence state with open/closed and comments like (busy, call proceeding, etc.)  Communication media (text, audio or video)  Communication capabilities (like video telephone, resolution, etc.)  Supported Codecs  Communication protocols (sip, smtp, etc. )  Addresses (IP, URIs, etc. )  Location (e.g. @office) / Local Time  Mood / present activities (e.g. in lecture) / Timetable  Privacy aspects

12. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 12 Architecture & Roles OnlineBusy

13. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 13 Agenda  Meaning of Presence  Architecture  Presence in SIP  Presence in IMS  Business Model and relevance to LTE  Conclusions

14. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 14 SIP and the Event Notification Framework B. Roach, „ Session Initiation Protocol (SIP)-Specific Event Notification“, IETF, RFC 3265 J. Rosenberg, „ A Presence Event Package for the Session Initiation Protocol (SIP)”, IETF, RFC 3856

15. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 15 Presence encoding - PIDF open sip:alice@opertaor.net Don't Disturb Please! 2001-10-27T16:49:29Z H. Sugano, S. Fujimoto, G. Klyne, A. Bateman, W. Carr, J. Peterson, „ Presence Information Data Format (PIDF)“, IETF RFC 3863

16. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 16 Problems Problem complexity 1:m on the UEconnection from each presentity to each watcher high bandwidth requirements on the UE presence changes has to be announced to each watcher changes last long for many watchersize of one change message ~16 kBit => 12,5 sec @ 64kbit (50w) needs a lot of computation power on UE user equipment has not powerful processors executing policiesAccess to presence state is executed at UE only single presence sourcePresence state is defined by a single device

17. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 17 Solution of these problems A. Niemi, Ed., „ Session Initiation Protocol (SIP) Extension for Event State Publication“, IETF, RFC 3909 A. B. Roach, B. Campbell, J. Rosenberg, „ A Session Initiation Protocol (SIP) Event Notification Extension for Resource Lists“, IETF, RFC 4662

18. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 18 Solutions Problem complexity 1:m on the UEOnly 2 connections (1 announce, 1 notify) high bandwidth requirements on the UE reduced bandwidth due only 2 connections (all overhead from SIP/IP) changes last long for many watcherreduced delay because only one announcement to the server needs a lot of computation power on UE fewer connection fewer processing power required executing policiespolicies executed on server only single presence sourceSeveral UE can define the presence state

19. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 19 Agenda  Meaning of Presence  Architecture  Presence in SIP  Presence in IMS  Business Model and relevance to LTE  Conclusions

20. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 20 IMS 3GPP TS 23.002

21. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 21 IMS Stores account data (HLR) Executes service relevant tasks Access point for other IMS systems Access point for own subscriber executes policies and security tasks User Equipmenty

22. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 22 Components in IMS Presence Source: Entity which creates presence information (presentity) Watcher: Entity which wants to follow the presence state Presence Server: Entity which stores the presence state of several entities Resource List Server: Entity which collects presence information for the watcher Presence XDMS: Entity which stores which watcher is allowed to see which data RLS XDMS: Entity which stores buddylists for watcher Clients, for creating and presenting presence information Server which process presence information Servers which store policies

23. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 23 The Architecture in IMS My buddies ? List of Alice buddies? Alice buddies: Bob Carol Get Bob state Get Carol state Policy for Alice from Bob? Policy for Alice from Carol? Accepted

24. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 24 Useability  Updating the presence state (by the user) “I am online, but I am still in a meeting!”  Configuring police rules for all watcher ”What are the watchers allowed to see?”

25. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 25 Privacy and Law  presence is a person related information and should be protected against unauthorized access  presence server executes policies, which are configured by the presentity  watcher could forward the presence information  network operator known about the presentity  Datenschutzgesetz 2000

26. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 26 Agenda  Meaning of Presence  Architecture  Presence in SIP  Presence in IMS  Business Model and relevance to LTE  Conclusions

27. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 27 LTE Offers: High bandwidth low latency Requires: Packet switched signalling Requires: Return of invest IMS Requires: High bandwidth low latency Offers: Packet switched signalling Offers: End2end signalling, QoS, charging, service interfaces Requires: Return of invest customer Offers: fees Offers: fees “Requires”: Services legacy services Requires: End2end signalling, charging, QoS Offers: Services packet based services Requires: End2end signalling, charging, service interfaces Offers: Services CashcowKillerapplication

28. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 28 Presence as Cashcow  could get very hard to sell basic presence  have to pay for all buddies over about 20 buddies (social aspects, removing old friends)  Does presence reduce the number of voice minutes (fewer voice box calls) ?  Extend presence functionality for paying customers (DSG2000)

29. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 29 Presence as Killerapplication for LTE/IMS  Killerapplication = driver for a new technology (WWW was the killerapplication for the internet)  UMTS had no killerapplication (most thought video telephony is it, but pure internet was it)  Needs a critical number of user in this service, before there is no possibility to sell  Offer as bundle with 4G/telephone account  Maybe presence gateways for 3G to 4G presence

30. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 30 Agenda  Meaning of Presence  Architecture  Presence in SIP  Presence in IMS  Business Model and relevance to LTE  Conclusions

31. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 31 Conclusions  presences indicates if somebody if wiling to accept a connection  P2P Presence works, but Server based scales  Easy configuration, intuitive meaning and easy usage of presence  privacy & DSG2000  not realistic to sell as a stand alone service (extend it)  could motivate people to switch from 3G/ISDN to 4G/IMS

32. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 32 References  J. Rosenberg, H. Schulzrinne, G. Camarillo, A. Johnston, J. Peterson, R. Sparks, M. Handley, E. Schooler, „SIP: Session Initiation Protocol“, IETF, RFC 3261  M. Day, J. Rosenberg, H. Sugano, „ A Model for Presence and Instant Messaging”, IETF, RFC 2778  A. B. Roach, „ Session Initiation Protocol (SIP)-Specific Event Notification“, IETF, RFC 3265  J. Rosenberg, „ A Presence Event Package for the Session Initiation Protocol (SIP)”, IETF, RFC 3856  J. Rosenberg, „ A Watcher Information Event Template-Package for the Session Initiation Protocol (SIP)”, IETF, RFC 3857  H. Sugano, S. Fujimoto, G. Klyne, A. Bateman, W. Carr, J. Peterson, „ Presence Information Data Format (PIDF)“, IETF RFC 3863  A. Niemi, Ed., „ Session Initiation Protocol (SIP) Extension for Event State Publication“, IETF, RFC 3909  E. Burger, Ed., „ A Mechanism for Content Indirection in Session Initiation Protocol (SIP) Messages“, IETF, RFC 4483  H. Khartabil, E. Leppanen, M. Lonnfors, J. Costa-Requena, „ Functional Description of Event Notification Filtering”, IETF, RFC 4660  A. B. Roach, B. Campbell, J. Rosenberg, „ A Session Initiation Protocol (SIP) Event Notification Extension for Resource Lists“, IETF, RFC 4662  J. Rosenberg, „ The Extensible Markup Language (XML) Configuration Access Protocol (XCAP)“, IETF, RFC 4825  3rd Generation Partnership Project; Technical Specification Group Services and System Aspects;Presence Service;Architecture and functional description(Release 8), TS 23.141 V8.1.0 (2008-06)  3rd Generation Partnership Project;Technical Specification Group Core Network and Terminals;Presence service using the IP Multimedia (IM) Core Network (CN) subsystem;Stage 3 (Release 8), TS 24.141 V8.1.0 (2008-06)  Presence SIMPLE Architecture (Candidate Version 1.1 – 28 Jan 2008), Open Mobile Alliance (OMA-AD-Presence_SIMPLE-V1_1- 20080128-C)  Enabler Release Definition for OMA Presence SIMPLE (Candidate Version 1.1 – 28 Jan 2008), Open Mobile Alliance (OMA-ERELD- Presence_SIMPLE-V1_1-20080128-C)  XML Document Management Architecture (Candidate Version 2.0 – 24 Jul 2007), Open Mobile Alliance (OMA-AD-XDM-V2_0-20070724- C)  Enabler Release Definition for XML Document Management (Candidate Version 2.0 – 24 Jul 2007), Open Mobile Alliance(OMA-ERELD- XDM-V2_0-20070724-C)

33. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 33 Thank you for your attention. Busyready f. questions

34. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 34 Messageflow

35. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 35 Messageflow

36. © 2008 Institute of Broadband CommunicationVienna University of Technology Slide 36 Messageflow