Introduction to Mobility

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Introduction to Mobility

• Do van Thanh
• Forelesning på NTNU
• 19. September 2001

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What is mobility?
Moving, in motion
Migrating, changing location
Immobile
Changing roles
Mobile
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What is mobility?

• In the Merriam-Webster's Collegiate Dictionary
• Main Entry 1mobilePronunciation 'mO-bl,
  -"bIl also -"bElFunction adjectiveEtymology
  Middle English mobyll, from Middle French mobile,
  from Latin mobilis, from movEre to moveDate
  15th century1 capable of moving or being moved
  MOVABLE lta mobile missile launchergt2 a
  changeable in appearance, mood, or purpose
  ltmobile facegt b ADAPTABLE, VERSATILE3 moving
  habitually or occasionally from one region or
  climate to another ltthe study of migratory
  birdsgt MIGRATORY4 a characterized by the
  mixing of social groups b having the
  opportunity for or undergoing a shift in status
  within the hierarchical social levels of a
  society ltsocially mobile workersgt5 marked by
  the use of vehicles for transportation ltmobile
  warfaregt6 of or relating to a mobile-
  mobility /mO-'bi-l-tE/ noun

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Mobility Types
Component Mobility
Terminal Mobility
Application/Service Portability/Mobility
Continuous
Session Mobility
Personal Mobility
Discret
Role Mobility
Portability
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Mobility Types

• Terminal mobility allows the terminal to change
  location while maintaining all services.
• Component mobility allows components e.g.
  earphone, microphone, etc. of a terminal to
  change location while maintaining all services.
  The components form a PAN (Personal Area Network)
• Personal mobility allows the user to access all
  services independently of terminals and networks.
• Role mobility allows the user to change roles and
  get access to distinct preferences, rights and
  limitations.

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Mobility Types

• Session mobility ensures that active sessions are
  not disrupted while users change terminals.
• Application/service portability or mobility
  allows software entities (codes, objects,
  processes) to be relocated from one machine to
  another or even moved between machines while
  processing.
• Ex Applets (code) Mobile Agents (object)

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Mobility Types

• Continuous Mobility enables continuous
  availability of services while the user moves.
• Ex Cellular systems
• Discrete Mobility enables the availability of
  services within certain areas and for certain
  access points, e.g. Home an Office, but not while
  moving from one area to another
• Ex DECT, Wireless LAN
• Portability is an example of discrete terminal
  mobility, where it is allowed to move a terminal
  from one plug to another.

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What is mobility?

• Mobility is confined to any particular networks.
• Mobile does not mean necessarily wireless since
  wireline networks can also offer mobility
• Wireless does not mean mobile since devices like
  parkometer, soft drink automate may communicate
  wireless and remain immobile.
• Mobility is not a service because mobility as
  such has no value for a user if not supplemented
  with other services.
• Mobility enhances the availability of other
  services.
• Mobility is a capability that can be added to any
  network system

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How can mobility be introduced?
Communication System
Application/Service Layer
Example IP-based networks do not originally
support mobility. By introducing Mobile IP than
discrete terminal mobility is supported
Mobility Layer
Network Layer
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The Mobility functions

• 1. Identification
• When moving the mobile entity needs to change
  Network Access Point
• Every mobile entity (person, terminal) must have
  its own identity
• For terminal mobility Every terminal must have
  an identity distinct from the Network Access
  point's one ( Network Address)
• For Personal mobility Every person must have an
  identity distinct from the terminal' one

Network
Access Points
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The Mobility functions

• 1. Identification
• Every entity has only one identity, but may have
  several identifiers
• An identifier is assigned uniquely to one mobile
  entity
• An identifier may be permanent or temporarily
  allocated according to time, location, context,
  etc.
• A human user may have several identifiers, one
  public such as email or personal such as login
  name
• Example In GSM
• Each terminal has a IMEI (International Mobile
  Equipment Identity)
• Each mobile subscriber has two identifiers
• IMSI (International Mobile Subscriber Identity)
• TMSI (Temporary Mobile Subscriber Identity)

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The Mobility Functions

• 2. Authentication
• It is not sufficient that the mobile entity
  identifies itself, but the system must be capable
  to verify that the mobile entity is the one it
  claimed to be
• A generic security function that is more
  necessary and more difficult to realize with
  mobility

claim
Principal
Entity Authentication
verify
delegation
claim
Claimant
Verifier
verify
claim
Trusted Third Party
Trusted Third Party
verify
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The Mobility Functions

• 2. Authentication
• Authentication methods relies on
• Something known, e.g password, pin code, etc.
• Something possessed, e.g magnetic card, smart
  card, etc.
• Some immutable characteristics, e.g. biometric
  identifiers
• Accepting that a 3rd entity has established
  authentication
• Context e.g. Location of principal
• Authentication method must fit the principal's
  characteristics
• Passive characteristics, e.g. Fingerprint,
  retinal, etc.
• Information storage capability
• Information exchange and processing capability
• Unique fixed location

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Mobility Functions

• 2. Authentication
• Authentication of the human user must in addition
  fit the used terminal when a user is allowed to
  use different terminals
• Authentication of the communication system by the
  mobile entity is also necessary ( Not in GSM
  but in UMTS)

SRES A3(Ki, RAND) Kc A8(Ki, RAND)
Authentication in GSM
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Mobility Functions

• 3. Access Control (or Authorisation)
• Even though a mobile entity is authenticated it
  is not necessarily authorised to access services.
• Access control' s goal is to counter the threat
  of unauthorized access.
• The access rights of the mobile entity is limited
  by
• Roaming restriction
• Time restriction
• Credit limit

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Mobility Functions

• 3. Access Control
• In a system supporting both terminal and personal
  mobility, a user is subject to three types of
  access control
• Access control for the use of the terminal
  (protection of 3rd party)
• Access control concerning the access to the
  communication system
• Access control concerning the use of the service
  requested

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Mobility Functions

• 4. Registration/Deregistration
• When a terminal moves and uses different access
  points
• Or when a user is using different terminals
• The system must know about it. A registration is
  necessary.
• Registration is the procedure that associates a
  mobile entity with a location directly or
  indirectly.

Network
Access Points
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Mobility Functions

• 4. Registration/Deregistration

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Mobility Functions

• 4. Registration/Deregistration
• Initiated by communication system
• On-the-fly or Lazy
• Predetermination
• Periodic
• Based on changes
• Initiated by mobile entity
• Example of GSM combination of both On-the-fly
  Predetermination

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Mobility Functions

• 4. Registration/Deregistration
• User registration
• Default registration
• Local registration
• Remote registration
• Registration through profiles
• User Deregistration
• Local deregistration
• Remote deregistration
• Forced deregistration

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Mobility Functions

• 5. User Profile Management
• Every user has specific preferences concerning
  services and their presentation, look and feel,
  etc.
• The setup data is saved in the user profile
• The profile can be extended to comprise a address
  book, a list of favorite links, etc.

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Mobility Functions

• 5. User Profile Management
• Requirements on the user profile
• The user should be able to modify his profile
  from any terminal anywhere and anytime
• The applications must be configured according to
  the profile
• Must be saved in a secured manner
• When the user is using different terminals and
  different access points, the usage of the profile
  must be in concordance with the terminal
  capabilities and the access point physical
  characteristics.

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Mobility Functions

• 5. User Profile Management
• With the demand for more customisation of
  applications combined with the plurality of
  terminals and devices, the User Profile will play
  a crucial role in the future
• However, not much has been done yet.
• The challenge is "Who is doing the User Profile
  Management?"

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Mobility Functions

• 6. Initiation of services/applications
• Distinction between service and application An
  application when being executed will offer a
  service to a user through a session.
• Ex The application "MS Word" when running will
  offer a word processing service to the user.
• The user must have the possibility to initiate or
  start the same services independently of the
  access point and the terminal.
• Application initiated by the user is called
  outgoing application (pull)
• Two cases according to the location of the
  applications
• Application located in the mobile terminal no
  problem
• Ex Laptop or PDA with all applications

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Mobility Functions

• 6. Initiation of services/applications
• Application located at the Home domain
• Alt 1. Establish a connection with Home domain
• Use for confidential or large applications which
  are not convenient to move e.g. Information,
  database, etc.
• Long connection
• Firewall problem since terminal has aforeign
  address
• Ex Telnet - rlogin

Home Domain
Application
Visiting Domain
Terminal
Client
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Mobility Functions

• 6. Initiation of services/applications
• Application located at the Home domain
• Alt 2. Static Replication of application logic
• The same application logic is replicated at all
  domains
• The user just use the replicate atvisiting
  domain
• Ex GSM the basic call logic is replicated and
  installed at all domains

Home Domain
Application
Visiting Domain
Terminal
Application
Client
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Mobility Functions

• 6. Initiation of services/applications
• Application located at the Home domain
• Alt 3. Dynamic replication of application logic
• The replication is done only on requestfrom the
  user
• The mobile agent may be used to copy, pack and
  bring an application to the visiting domain
• The Mobile agent technology is not yet mature
  and suffers from insufficient security and
  standardisation

Home Domain
Application
Move
Visiting Domain
Terminal
Application
Client
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Mobility Functions
Terminal Y

• 7. Delivery of services
• The services are initiated by someone else e.g.
  Another user, the system, etc.
• Also called incoming services (Push).
• The system must
• find the terminalthat the user is using
• establish connectionto the respective visiting
  domain
• Deliver output to the terminal according tothe
  terminal capabilities
• Ex Mobile IP

Client
Home Domain
Application X
initiates
Application
Visiting Domain
Terminal
Client
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Mobility Functions

• 8. Service/facility discovery and usage.
• When visiting a domain the user may want to use
  facilities like printers, faxes, projectors, etc.
  or services like local informations, weather,etc.
• Nowadays it is not simple since complex tasks
  must be done, e.g. Discover the
  Services/Facilitiesavailable, install drivers,
  etc.
• One solution could be using mobile agent
  technology

Home Domain
Application
agent
move
Visiting Domain
Terminal
Application
Client
agent
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Mobility Functions

• 9. Support of mobility-based applications
• Mobility-based applications are born with
  mobility. They are meaningless without mobility.
• Examples are taxi dispatch, fleet management,
  public safety, etc.
• Such application needs location information that
  the mobility layer has.
• Provides a mobility interface to mobility-based
  applications
• Ex
• GetAddress (in TerminalID, out Address, Out
  Status)
• GetTerminal (in UserID, out TerminalID, Out
  Status)
• For UMTS, OSA (Open Service Architecture) /Parlay
  has specified such a mobility interface

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Conclusion
Generic Mobility Layer