Title: Presence in the IP Multimedia Subsystem
1Presencein the IP Multimedia Subsystem
- Happenhofer Marco
- June 26, 2008
2Switched 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 ?
4Agenda
- Meaning of Presence
- Architecture
- Presence in SIP
- Presence in IMS
- Business Model and relevance to LTE
- Conclusions
5Agenda
- Meaning of Presence
- Architecture
- Presence in SIP
- Presence in IMS
- Business Model and relevance to LTE
- Conclusions
6Definition 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.
7History
- 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
8Standardisation 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
9Agenda
- Meaning of Presence
- Architecture
- Presence in SIP
- Presence in IMS
- Business Model and relevance to LTE
- Conclusions
10What information carries Presence
Presence describes the state of a buddy binary
with online or offline. in a homogen
communication system
11What 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
12Architecture Roles
13Agenda
- Meaning of Presence
- Architecture
- Presence in SIP
- Presence in IMS
- Business Model and relevance to LTE
- Conclusions
14SIP 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
15Presence 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
16Problems
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
17Solution 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
18Solutions
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
19Agenda
- Meaning of Presence
- Architecture
- Presence in SIP
- Presence in IMS
- Business Model and relevance to LTE
- Conclusions
20IMS
3GPP TS 23.002
21IMS
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
22Components 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
23The Architecture in IMS
24Useability
- 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?
25Privacy 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
26Agenda
- Meaning of Presence
- Architecture
- Presence in SIP
- Presence in IMS
- Business Model and relevance to LTE
- Conclusions
27LTE
28Presence 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)
29Presence 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
30Agenda
- Meaning of Presence
- Architecture
- Presence in SIP
- Presence in IMS
- Business Model and relevance to LTE
- Conclusions
31Conclusions
- 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
32References
- 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
)
33Thank you for your attention.
34Messageflow
35Messageflow
36Messageflow