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Introduction to Mobility

Do van Thanh

Forelesning p NTNU

19. September 2001

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What is mobility?

Immobile

Moving, in

motion

Migrating,

changing

location

Changing

rolesMobile

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What is mobility?

In the Merriam-Webster's Collegiate Dictionary:Main Entry: 1mobile

Pronunciation: 'mO-b&l, -"bIl also -"bElFunction: adjectiveEtymology: Middle English mobyll, from Middle French mobile, from Latinmobilis, from movEre to moveDate: 15th century1 : capable of moving or being moved : MOVABLE 2 a : changeable in appearance, mood, or purpose b :ADAPTABLE, VERSATILE3 : moving habitually or occasionally from one region or climate to another MIGRATORY4 a : characterized by the mixing of social groups b : having the opportunity foror undergoing a shift in status within the hierarchical social levels of a society5 : marked by the use of vehicles for transportation 6 : of or relating to a mobile

- mobility /mO-'bi-l&-tE/ noun

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Mobility Types

Terminal Mobility

Personal Mobility

Role Mobility

SessionMobility

Visiting

Domain

Visiting Services

CommunicationComputing

Visiting Facilities

PrintersFax

Projector

Application/Service

Portability/Mobility

Continuous

Discr

et

Portability

Component Mobility

Home

Services/Applications

CommunicationVoice telephony

Multimedia

conference

MailSynchronous

Asynchronous

ComputingWord Processor

Spreadsheet

Information

DatabaseGames

E-commerce

Home

DomainData

Profile

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Mobility Types

Terminal mobility allows the terminal to change locationwhile maintaining all services.

Component mobility allows components e.g. earphone,

microphone, etc. of a terminal to change location whilemaintaining all services. The components form a PAN

(Personal Area Network)

Personal mobility allows the user to access all servicesindependently of terminals and networks.

Role mobility allows the user to change roles and getaccess to distinct preferences, rights and limitations.

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Mobility Types

Session mobility ensures that active sessions are notdisrupted while users change terminals.

Application/service portability or mobility allowssoftware entities (codes, objects, processes) to berelocated 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 fromone 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 wirelessand 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

Network Layer

Mobility Layer

Application/Service LayerExample:

IP-based networks do not

originally support mobility.

By introducing Mobile IP

than discrete terminal

mobility is supported

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The Mobility functions

1. Identification

When moving the mobile entityneeds to change Network AccessPoint

Every mobile entity (person,terminal) must have its ownidentity

For terminal mobility: Everyterminal must have an identitydistinct from the Network Accesspoint's one ( Network Address)

For Personal mobility: Every

person must have an identitydistinct from the terminal' one

Access Points

Network

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The Mobility functions

1. Identification

Every entity has only one identity, but may have severalidentifiers

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 publicsuch as email or personal such as login name

Example: 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)

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The Mobility Functions

2. Authentication

It is not sufficient that the mobile entity identifies itself, butthe system must be capable to verify that the mobile entityis the one it claimed to be

A generic security function that is more necessary and

more difficult to realize with mobility

Principal Entity Authentication

claim

verify

Claimant Verifier

claim

verify

Trusted Third Party Trusted Third Party

claim

verify

delegation

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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 terminalwhen a user is allowed to use different terminals

Authentication of the communication system by the mobile entity is alsonecessary ( Not in GSM but in UMTS)

MS VLR HLR

IMSI or TMSI

IMSI, VLR

a set of (RAND;SRES;Kc)

RAND

SRES

stored

Ki

Authentication in GSM

SRES = A3(Ki, RAND)

Kc= A8(Ki, RAND)

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Mobility Functions

3. Access Control (or Authorisation)

Even though a mobile entity is authenticated it is notnecessarily authorised to access services.

Access control' s goal is to counter the threat ofunauthorized 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 ControlIn a system supporting both terminal and personal

mobility, a user is subject to three types of accesscontrol: Access control for the use of the terminal (protection of3rd

party)

Access control concerning the access to the communicationsystem

Access control concerning the use of the service requested

User

Terminal telecom system Services

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Mobility Functions

4.Registration/Deregistration

When a terminal moves anduses different access points

Or when a user is using different

terminalsThe system must know about it. A

registration is necessary.

Registration is the procedure thatassociates a mobile entity with a

location directly or indirectly.

Access Points

Network

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Mobility Functions

4.Registration/Deregistration

User

Terminal

Network Access Point

User Profile

Terminal Capability

has

has

registered_at

registered_at

1+

Physical Characteristicshas

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Mobility Functions4.

R

egistration/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

Registration

GNAP

NAP NAPNAP

Registration

MTA

NAP NAPNAP

on the fly method

a) b)

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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 Functions5. UserProfile Management

Every user has specific preferences concerning services andtheir 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.

User_Profile

Routing_Info Charging_Info Security_InfoService_Restriction

User_Application_Profile

Routing_Info Charging_Info Security_InfoAppl_

Spec_InfoRestrictionAppl_ Appl_ Appl_ Appl_

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Mobility Functions

5. UserProfile Management Requirements on the user profile:

The user should be able to modify his profile from any terminalanywhere 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 differentaccess points, the usage of the profile must be inconcordance with the terminal capabilities and the accesspoint physical characteristics.

User

Terminal

Network Access Point

is represented by

is represented by

is represented by

User Profile

Terminal Capability

Physical Characteristics

has

has

has

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Mobility Functions

5. UserProfile 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 sameservices 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

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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 applicationswhich are not convenient to move e.g.Information, database, etc.

Long connection Firewall problem since terminal has a

foreign address

Ex: Telnet - rlogin

Home Domain

Visiting DomainTerminal

Application

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 replicatedat all domains

The user just use the replicate at

visiting domain Ex: GSM the basic call logic is

replicated and installed at alldomains

Home Domain


ApplicationClient

Application

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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 request

from the user

The mobile agent may be used tocopy, pack and bring an application to thevisiting domain

The Mobile agent technology is not yetmature and suffers from insufficient securityand standardisation

Home Domain


ApplicationClient

Application

Move

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Mobility Functions7. 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 connection

to the respective visiting domain Deliver output to the terminal according to

the terminal capabilities

Ex: Mobile IP

Home Domain


Application

Client

Application X

Terminal Y

Client

initiates

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Mobility Functions8. Service/facility discovery and usage.

When visiting a domain the user may want to usefacilities like printers, faxes, projectors, etc. or

services like local informations, weather,etc.

Nowadays it is not simple sincecomplex tasks must be done, e.g.

Discover the Services/Facilities

available, install drivers, etc.

One solution could be usingmobile agent technology

Home Domain


ApplicationClient

Application

agent

agent

move

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Mobility Functions

9. Support of mobility-based applications Mobility-based applications are born with mobility. Theyare meaningless without mobility.

Examples are taxi dispatch, fleet management, publicsafety, etc.

Such application needs location information that themobility layer has.

Provides a mobility interface to mobility-basedapplications Ex:

GetAddress (in TerminalID, out Address, Out Status)

GetTerminal (in UserID, out TerminalID, Out Status)

For UMTS, OSA (Open Service Architecture) /Parlay hasspecified such a mobility interface

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Conclusion

Registration

/Deregistration

AuthenticationAccess Control

Identification

User Profile Mgmt

Delivery of services

Initiation of services

Mobility-based

application support

Discovery of

Service/facility

Generic Mobility Layer

Documents

MOBILIThan