Introduction to MobilityDo van Thanh

Forelesning p NTNU19. September 2001

What is mobility?

ImmobileMoving, in motionMigrating, changing locationChangingrolesMobile

What is mobility?In the Merriam-Webster's Collegiate Dictionary:Main Entry: 1mobile Pronunciation: 'mO-b&l, -"bIl also -"bEl Function: adjective Etymology: Middle English mobyll, from Middle French mobile, from Latin mobilis, from movEre to move Date: 15th century 1 : capable of moving or being moved : MOVABLE 2 a : changeable in appearance, mood, or purpose b : ADAPTABLE, VERSATILE 3 : moving habitually or occasionally from one region or climate to another MIGRATORY 4 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 5 : marked by the use of vehicles for transportation 6 : of or relating to a mobile - mobility /mO-'bi-l&-tE/ noun

Mobility TypesTerminal MobilityPersonal MobilityRole MobilitySession MobilityApplication/Service Portability/MobilityContinuousDiscretPortabilityComponent Mobility

Mobility TypesTerminal 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.

Mobility TypesSession 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)

Mobility TypesContinuous Mobility enables continuous availability of services while the user moves.Ex: Cellular systemsDiscrete 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 anotherEx: DECT, Wireless LANPortability is an example of discrete terminal mobility, where it is allowed to move a terminal from one plug to another.

What is mobility?Mobility is confined to any particular networks.Mobile does not mean necessarily wireless since wireline networks can also offer mobilityWireless 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

How can mobility be introduced?Communication SystemNetwork LayerMobility Layer Application/Service LayerExample: IP-based networks do not originally support mobility.By introducing Mobile IP than discrete terminal mobility is supported

The Mobility functions1. IdentificationWhen moving the mobile entity needs to change Network Access PointEvery mobile entity (person, terminal) must have its own identityFor 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

Access PointsNetwork

The Mobility functions1. IdentificationEvery entity has only one identity, but may have several identifiersAn identifier is assigned uniquely to one mobile entityAn 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 nameExample: In GSMEach terminal has a IMEI (International Mobile Equipment Identity)Each mobile subscriber has two identifiers: IMSI (International Mobile Subscriber Identity)TMSI (Temporary Mobile Subscriber Identity)

The Mobility Functions2. AuthenticationIt 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 beA generic security function that is more necessary and more difficult to realize with mobility PrincipalEntity AuthenticationclaimverifyClaimantVerifierclaimverifyTrusted Third PartyTrusted Third Partyclaimverifydelegation

The Mobility Functions2. AuthenticationAuthentication 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 identifiersAccepting that a 3rd entity has established authenticationContext e.g. Location of principalAuthentication method must fit the principal's characteristics:Passive characteristics, e.g. Fingerprint, retinal, etc.Information storage capabilityInformation exchange and processing capabilityUnique fixed location

Mobility Functions2. AuthenticationAuthentication of the human user must in addition fit the used terminal when a user is allowed to use different terminalsAuthentication of the communication system by the mobile entity is also necessary ( Not in GSM but in UMTS)

Authentication in GSMSRES = A3(Ki, RAND)Kc= A8(Ki, RAND)

Mobility Functions3. 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 restrictionTime restrictionCredit limit

Mobility Functions3. Access ControlIn 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 systemAccess control concerning the use of the service requested

Mobility Functions4. Registration/DeregistrationWhen a terminal moves and uses different access pointsOr when a user is using different terminalsThe system must know about it. A registration is necessary.Registration is the procedure that associates a mobile entity with a location directly or indirectly.

Access PointsNetwork

Mobility Functions4. Registration/Deregistration

Mobility Functions4. Registration/DeregistrationInitiated by communication systemOn-the-fly or LazyPredetermination:PeriodicBased on changesInitiated by mobile entityExample of GSM: combination of both On-the-fly & Predetermination

Mobility Functions4. Registration/DeregistrationUser registrationDefault registrationLocal registrationRemote registrationRegistration through profilesUser DeregistrationLocal deregistrationRemote deregistrationForced deregistration

Mobility Functions5. User Profile ManagementEvery user has specific preferences concerning services and their presentation, look and feel, etc.The setup data is saved in the user profileThe profile can be extended to comprise a address book, a list of favorite links, etc.

Mobility Functions5. User Profile ManagementRequirements on the user profile:The user should be able to modify his profile from any terminal anywhere and anytimeThe applications must be configured according to the profileMust be saved in a secured mannerWhen 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.

Mobility Functions5. User Profile ManagementWith 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 futureHowever, not much has been done yet.The challenge is: "Who is doing the User Profile Management?"

Mobility Functions6. Initiation of services/applicationsDistinction 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 problemEx: Laptop or PDA with all applications

Mobility Functions6. Initiation of services/applicationsApplication located at the Home domain:Alt 1. Establish a connection with Home domainUse for confidential or large applications which are not convenient to move e.g. Information, database, etc.Long connectionFirewall problem since terminal has a foreign addressEx: Telnet - rlogin

Home DomainVisiting DomainTerminalApplicationClient

Mobility Functions6. Initiation of services/applicationsApplication located at the Home domain:Alt 2. Static Replication of application logicThe same application logic is replicated at all domainsThe user just use the replicate at visiting domainEx: GSM the basic call logic is replicated and installed at all domains

Home DomainVisiting DomainTerminalApplicationClientApplication

Mobility Functions6. Initiation of services/applicationsApplication located at the Home domain:Alt 3. Dynamic replication of application logicThe replication is done only on request from the userThe 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 DomainVisiting DomainTerminalApplicationClientApplicationMove

Mobility Functions7. Delivery of servicesThe services are initiated by someone else e.g. Another user, the system, etc.Also called incoming services (Push).The system must find the terminal that the user is using establish connection to the respective visiting domainDeliver output to the terminal according to the terminal capabilitiesEx: Mobile IP

Home DomainVisiting DomainTerminalApplicationClientApplication XTerminal YClientinitiates

Mobility Functions8. 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/Facilities available, install drivers, etc.One solution could be using mobile agent technology

Home DomainVisiting DomainTerminalApplicationClientApplicationagentagentmove

Mobility Functions9. Support of mobility-based applicationsMobility-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 applicationsEx: 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

ConclusionGeneric Mobility Layer