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Presence in the IP Multimedia Subsystem. Happenhofer Marco June 26, 2008. 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. Imaging: - PowerPoint PPT Presentation
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© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 1
Presencein the IP Multimedia Subsystem
Happenhofer MarcoJune 26, 2008
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 2
Switched of your mobile phone?
Will only prevent ringing of your phone, butit will not prevent the caller to call you andthe caller will not know why he did not reach you
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 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 ?
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 4
Agenda
Meaning of Presence Architecture Presence in SIP Presence in IMS Business Model and relevance to LTE Conclusions
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 5
Agenda
Meaning of Presence Architecture Presence in SIP Presence in IMS Business Model and relevance to LTE Conclusions
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 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
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 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
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 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
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 9
Agenda
Meaning of Presence Architecture Presence in SIP Presence in IMS Business Model and relevance to LTE Conclusions
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 10
What information carries Presence
Presence describes the state of a buddy binary with „online“ or „offline“.
in a homogen communication system
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 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
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 12
Architecture & Roles
OnlineBusy
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 13
Agenda
Meaning of Presence Architecture Presence in SIP Presence in IMS Business Model and relevance to LTE Conclusions
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 14
SIP and the Event Notification Framework
B. Roach, „ Session Initiation Protocol (SIP)-Specific Event Notification“, IETF, RFC 3265J. Rosenberg, „ A Presence Event Package for the Session Initiation Protocol (SIP)”, IETF, RFC 3856
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 15
Presence encoding - PIDF
<?xml version="1.0" encoding="UTF-8"?>
<presence entity="pres:[email protected]">
<tuple id="bs35r9">
<status>
<basic>open</basic>
</status>
<contact priority="0.8">sip:[email protected]</contact>
<note xml:lang="en">Don't Disturb Please!</note>
<timestamp>2001-10-27T16:49:29Z</timestamp>
</tuple>
</presence>H. Sugano, S. Fujimoto, G. Klyne, A. Bateman, W. Carr, J. Peterson, „ Presence Information Data Format (PIDF)“, IETF RFC 3863
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 16
Problems
Problem
complexity 1:m 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 => 12,5 sec @ 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
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 17
Solution of these problems
A. Niemi, Ed., „ Session Initiation Protocol (SIP) Extension for Event State Publication“, IETF, RFC 3909A. B. Roach, B. Campbell, J. Rosenberg, „ A Session Initiation Protocol (SIP) Event Notification Extension for Resource Lists“, IETF, RFC 4662
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 18
Solutions
Problem
complexity 1:m 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
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 19
Agenda
Meaning of Presence Architecture Presence in SIP Presence in IMS Business Model and relevance to LTE Conclusions
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 20
IMS
E-CSCF
P-CSCF
S-CSCF MGCF
HSS Cx
IP Multimedia Networks
IMS-MGW
CS Network
Mn
Mb
Mg
Mm
MRFP
Mb
Mr
Mb
Legacy mobile signalling Networks
I-CSCF
Mw
Mw
Gm
BGCF Mj Mi
BGCF
Mk Mk C, D,
Gc, Gr
UE
Mb
Mb
Mb
MRFC
SLF Dx
Mp
CS
CS
Rx
Mm
LRF
Ml
Le
BGCF
Mi
LCS Client
Cx
Dx
AS
Sh
Ut
Mw
ISC
IBCF Mx
Mx
Mx
Ma
Dh
TrGW Izi
Ici Ix
Mg
3GPP TS 23.002
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 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
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 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
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 23
The Architecture in IMS
My buddies?
List of Alice buddies?
Alice buddies:BobCarol
Get Bob state
Get Carol state
Policy for Alice from Bob?
Policy for Alice from Carol?
Accepted Accepted
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 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?”
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 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
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 26
Agenda
Meaning of Presence Architecture Presence in SIP Presence in IMS Business Model and relevance to LTE Conclusions
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 27
LTE
LTEOffers:High bandwidthlow latency
Requires:Packet switched signalling
Requires:Return of invest
IMS
Requires:High bandwidthlow latencyOffers:
Packet switched signalling
Offers:End2end signalling, QoS, charging, service interfaces
Requires:Return of invest
customerOffers:fees
Offers:fees
“Requires”:Services
legacyservices
Requires:End2end signalling, charging, QoS
Offers:Services
packet based
services
Requires:End2end signalling, charging, service interfaces
Offers:Services
Cashcow Killerapplication
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 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)
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 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
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 30
Agenda
Meaning of Presence Architecture Presence in SIP Presence in IMS Business Model and relevance to LTE Conclusions
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 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
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 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)
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 33
Thank you for your attention.
Busyready f. questions
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 34
Messageflow
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 35
Messageflow
© 2008 Institute of Broadband Communication Vienna University of TechnologySlide 36
Messageflow