Presence in the IP Multimedia Subsystem

1
Presencein the IP Multimedia Subsystem

• Happenhofer Marco
• June 26, 2008

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

• 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
Agenda

• Meaning of Presence
• Architecture
• Presence in SIP
• Presence in IMS
• Business Model and relevance to LTE
• Conclusions

5
Agenda

• Meaning of Presence
• Architecture
• Presence in SIP
• Presence in IMS
• Business Model and relevance to LTE
• Conclusions

6
Definition of Presence
A presence .. system allows users to subscribe
to each other and be notified of changes in
state, ...IETF
A Presence Service is a software system whose
role is to collect and disseminate presence
information, subject to a wide variety of
controls. OMA
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. Wikipediaen
Presence describes the social willingness and
technical possibilities (of a subscriber) to
accept a connection.
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
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
Agenda

• Meaning of Presence
• Architecture
• Presence in SIP
• Presence in IMS
• Business Model and relevance to LTE
• Conclusions

10
What information carries Presence
Presence describes the state of a buddy binary
with online or offline. in a homogen
communication system
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. _at_office) / Local Time
• Mood / present activities (e.g. in lecture) /
  Timetable
• Privacy aspects

12
Architecture Roles
13
Agenda

• Meaning of Presence
• Architecture
• Presence in SIP
• Presence in IMS
• Business Model and relevance to LTE
• Conclusions

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
Presence encoding - PIDF
lt?xml version"1.0" encoding"UTF-8"?gt
ltpresence entity"presalice_at_opertaor.net"gt
lttuple id"bs35r9"gt ltstatusgt
ltbasicgtopenlt/basicgt lt/statusgt
ltcontact priority"0.8"gtsipalice_at_opertaor.netlt/co
ntactgt ltnote xmllang"en"gtDon't Disturb
Please!lt/notegt lttimestampgt2001-10-27T1649
29Zlt/timestampgt lt/tuplegt lt/presencegt
H. Sugano, S. Fujimoto, G. Klyne, A. Bateman, W.
Carr, J. Peterson, Presence Information Data
Format (PIDF), IETF RFC 3863
16
Problems
Problem
complexity 1m on the UE connection 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 watcher size of one change message 16 kBit gt 12,5 sec _at_ 64kbit (50w)
needs a lot of computation power on UE user equipment has not powerful processors
executing policies Access to presence state is executed at UE
only single presence source Presence state is defined by a single device
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
Solutions
Problem
complexity 1m on the UE Only 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 watcher reduced delay because only one announcement to the server
needs a lot of computation power on UE fewer connection fewer processing power required
executing policies policies executed on server
only single presence source Several UE can define the presence state
19
Agenda

• Meaning of Presence
• Architecture
• Presence in SIP
• Presence in IMS
• Business Model and relevance to LTE
• Conclusions

20
IMS
3GPP TS 23.002
21
IMS
Access point for other IMS systems
Stores account data (HLR)
Executes service relevant tasks
Access point for own subscriber executes policies
and security tasks
User Equipmenty
22
Components in IMS
Presence SourceEntity which creates presence
information (presentity)
Presence ServerEntity which stores the presence
state of several entities
Presence XDMSEntity which stores which watcher
is allowed to see which data
WatcherEntity which wants to follow the
presence state
Resource List ServerEntity which collects
presence information for the watcher
RLS XDMSEntity which stores buddylists for
watcher
Clients, for creating and presenting presence
information
Server which process presence information
Servers which store policies
23
The Architecture in IMS
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
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
Agenda

• Meaning of Presence
• Architecture
• Presence in SIP
• Presence in IMS
• Business Model and relevance to LTE
• Conclusions

27
LTE
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
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
Agenda

• Meaning of Presence
• Architecture
• Presence in SIP
• Presence in IMS
• Business Model and relevance to LTE
• Conclusions

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
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
  AspectsPresence ServiceArchitecture and
  functional description(Release 8), TS 23.141
  V8.1.0 (2008-06)
• 3rd Generation Partnership ProjectTechnical
  Specification Group Core Network and
  TerminalsPresence service using the IP
  Multimedia (IM) Core Network (CN) subsystemStage
  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
Thank you for your attention.
34
Messageflow
35
Messageflow
36
Messageflow