Mobility extensions to H'323

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Mobility extensions to H.323

• Stefan Föckel, Wintersemester 2000/2001

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Outline

• What is meant by mobility ?
• Documents concerning mobility in H.323
• H.323 Annex H
• New functional entities to H.323
• Functional architecture of mobility enhanced
  H.323 systems
• Service Execution Location
• Mobility Management procedures
• Example scenarios from the current H.323 Annex H
  draft
• Open issues

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What is mobility ?
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Definition What is mobility ?

• Terminal Mobility
• Ability of a terminal to be connected to the
  network irrespective of the location
• Divided into two sub-categories
• Discrete Terminal Mobility change location
  between active sessions (Roaming)
• Continous Terminal Mobility change location
  while in active sessions (Handover)
• User Mobility
• Ability for a user to maintain the same User
  Identity irrespective of terminals or terminal
  types
• It can be argued, that most Roaming issues really
  concern User Mobility

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Definition What is mobility ? (cont.)

• Service Mobility
• Ability for a user to access the same
  (subscribed) set of services irrespective of the
  location, of the user and the terminal, that is
  used for that purpose
• In practice not really irrespective of User
  Mobility, because it is possible to execute some
  services directly in the Terminal
• If the network is supposed to offer Service
  Mobility, the User nevertheless needs to be
  identified

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H.323 Mobility Related Documents
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H.323 Mobility Related Documents

• H.323 Annex H
• Architectural and signaling extensions as well as
  new procedures to H.323 needed for mobility
• Basic H.323 mobility document
• Editorship NOKIA
• Title User, Terminal and Service Mobility
• Active work going on
• Determined (assurance that the document will be
  done) in 11/2000
• Expected to be decided in 2002

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H.323 Mobility Related Documents (cont.)

• H.323 Annex I
• Addresses problems caused by lower layer
  protocols (below transport layer) allowing
  mobility (such as Mobile IP)
• Error correction methods
• Editorship Toshiba
• Title Communication over Error Prone Channels
• Very little work done

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H.323 Mobility Related Documents (cont.)

• H.246 Annex E
• Extensions to H.323 to allow the PLMNs (e.g. GSM
  networks) to access H.323
• Editorship Intel
• Title H.323 to PLMN interworking
• Decided 11/2000

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H.323 Mobility Related Documents (cont.)

• H.323 Annex H handles almost only User and
  Service Mobility
• H.323 level handovers are not in the scope of the
  first version of H.323 Annex H
• Following the definition of Discrete Terminal
  Mobility and User Mobility, Roaming is part of
  Terminal Mobility
• H.246 Annex E handles User and Service Mobility
  interworking between H.323 systems and PLMNs
• No inter-system handover between H.323 systems
  and PLMNs are defined
• H.323 Annex I should handle issues caused by
  usage of lower layer protocols

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H.323 Mobility Related Documents (cont.)
Interworking Function (IWF) H.246 Annex E
PLMN IWF (interworking Function) to allow
existing Mobile subscribers on ANSI-41 or GSM or
PDC Public Land Mobile Networks to Roam into
H.323 Networks with User Identification Module
(UIM)
H.323 Annex H Service/application layer for -
User Mobility - Terminal Mobility - Service
Mobility Mobility Management functions -
HLF - VLF - AuF - IWF

PLMN
H.323 Annex I
Codec level error handling
Generic packet network layer (e.g. IP issues)
Radio network access specific (W-CDMA,
CDMA-2000, EDGE, WIRELESS-LAN, etc.)
Fixed network access specific (xDSL, Cable
modem, Ethernet, etc.)
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H.323 Annex H
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Architecture Reference Points
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New functional entities to H.323

• Home Location Function (HLF)
• Database in charge of management of mobile
  subscribers
• A H.323 Domain may contain one or more HLFs
  depending on the number of subscribers, capacity,
  equipment etc.
• Contains information about the users associated
  through subscription
• Location information for charging and routing (at
  least with accuracy of the VLF holding more
  precise information)
• Usually more permanent data about the user (like
  all possible global User Identities)
• Separate User Service Database functionality
  containing the service profiles for a user
  belonging to the HLF (open issue)
• Analogous to Home Location Register (HLR) of
  PLMNs

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New functional entities to H.323 (cont.)

• Visitor Location Function (VLF)
• In charge of one or more several H.323 zones
• Contains information about users currently
  registered to gatekeepers of the VLFs serving
  area
• At least information about the location of Users
  with accuracy of the Gatekeeper holding more
  precise information (VLF knows the Gatekeeper to
  which the User is currently registered)
• At least one User Identity that is used as key
  when location data is accessed
• May contain parts of service profiles of the
  User, that are currently in the serving area of
  the VLF (open issue)
• Analogous with the Visitor Location Register
  (VLR) of PLMNs

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New functional entities to H.323 (cont.)

• Authentication Function (AuF)
• Contains information needed for authenticating
  the User (or to aquire that information from a
  Certificate Authority)
• Authentication keys, shared secrets, public keys
• Can be associated with the HLF and/or the
  gatekeeper
• Mostly analogous with the Authentication Centre
  of PLMNs

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New functional entities to H.323 (cont.)

• Interworking Function (IWF)
• Mobility Management Interworking Function
• Associated with a Gatekeeper and/or a Gateway
  with respect to the mobility functions
• Provides functionality to allow interworking
  between a Mobile H.323 Network and the PLMN or
  fixed networks (ISDN, PSTN, etc.)
• Only applicable if compatible services exists
• No IWFs are defined in the first version of H.323
  Annex H

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New functional entities to H.323 (cont.)

• The new funtional entities can be co-located with
  any other functional entities (except a Terminal)
• They must be in the same Administrative Domain

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Basic concepts

• Network Point of Attachment (NPoA)
• H.323 Annex H definition the address by which
  packets reach an endpoint
• The network node, which the H.323 system of the
  Terminal accessing the system (typically the IP
  address)
• H.323 Point of Attachment (HPoA)
• H.323 Annex H definition the gatekeeper with
  which the H.323 terminal is registered
• Location
• H.323 Annex H definition the Network Point of
  Attachment through which the User/Terminal is
  currently accessing the H.323 system (typically
  an IP address)

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Basic concepts (cont.)

• Scenario
• H.323 Annex H definition a description of the
  network types and interfaces between network
  participating in a call
• Administrative Domain
• A collection of H.323 entities administered by
  one administrative entity ( H.323 service
  provider)
• Can consist of one or more gatekeepers (one or
  more zones)
• Home Administrative Domain
• H.323 Annex H definition the Administrative
  Domain that is related by subscription to the
  mobile H.323 user. It permanently contains user
  specific data including location, authentication
  and service profile information related to the
  mobile H.323 user.

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Basic concepts (cont.)

• Visited Administrative Domain
• An Administrative Domain, that is serving an
  active mobile H.323 user, but is not the Home
  Administrative Domain
• Serving Administrative Domain
• The (Visited or Home) Administrative Domain that
  is serving an active mobile H.323 user
• Home Gatekeeper
• A gatekeeper in the Home Administrative Domain of
  a User
• A gatekeeper specifically configured as Home
  Gatekeeper (not all GKs in the Home
  Administrative Domain)

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Service Execution Location

• Service Execution in Home Administrative Domain
• Services (i.e. calls) are controlled in the Home
  Administrative Domain
• The Home Gatekeeper is always controlling the
  call
• The Terminal/User must still register to a
  gatekeeper in the Serving Administrative Domain
• Service Execution in Visited Administrative
  Domain
• Services are controlled in the Visited
  Administrative Domain (by a Gatekeeper in that
  Administrative Domain)

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Mobility Management Procedures

• Three classes of MM procedures
• HLF Address Space Announcement procedures
• Location Updating procedures
• GK discovery
• Registration
• Unregistration
• Call Related Mobility Management procedures
• Call originating from mobile user
• Call delivery to mobile user

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Mobility Management Procedures (cont.)

• Location updating procedures
• Intra-zone location update
• Inter-zone location update
• Inter-domain location update
• Call-related Mobility Management procedures
• Intra-zone calls
• Inter-zone calls
• Inter-domain calls

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Examples
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Intra-zone location update
VLF/ BE
GK
HLF/ BE
AuF
Packet Network
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Inter-zone Inter-domainlocation update
HLF/ BE
VLF/ BE
Home Network
New visited Network
Old visited Network
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Intra-zone call
Packet Network
Called party
Calling party
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Intra-zone call
Packet Network
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Intra-zone call
Packet Network
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Inter-domain call
Calling Network
Calling party
HLF/ BE
Visited Network
Home Network
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Inter-domain call
Calling Network
HLF/ BE
Visited Network
Home Network
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Open Issues

• Security
• Accounting/Charging (billing)
• Supplementary Services
• QoS issues related to mobility
• Multimedia aspects related to mobility
• H.323 level handovers

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Backup slides
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Recall H.323 Network Elements
Scope of H.323
H.323 Terminal
H.323 MCU
H.323 Gateway
H.323 Gatekeeper
H.323 Terminal
H.323 Terminal
Guaranteed QOS LAN
GSTN
N-ISDN
B-ISDN
H.310 terminal operating in H.321 mode
V.70 Terminal
H.324 Terminal
Speech Terminal
H.322 Terminal
Speech Terminal
H.320 Terminal
H.321 Terminal
H.321 Terminal
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Recall H.323 Terminal Equipment
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Recall H.323/PSTN Gateway
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Recall H.323 Zone