mobility - sti-innsbruck.at · prof. dr. thomas strang [email protected] ubiquitous...
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Variations of Mobility
Mobility is a major reason of dynamics in a system
Pretty much user driven
Several variations of mobility are considered:Terminal MobilityDevice MobilityUser MobilityCode MobilityService MobilitySession MobilityPersonal MobilityAd-hoc MobilityMode Mobility
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Terminal Mobility
Terminal mobility is the conventional mobility management known from wireless communication systems
Two major tasks while traversing several subnetworks of one or more administrative domains are
handover management (keeping connection alive while terminal moving)
location management (keeping track of terminal while in idle/standby mode to deliver incoming calls)
Used only with carrier services
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Device Mobility
Degree of mobility of a device is determined byits sizeits weightits battery endurance
Portable devices are most of the time stationary, but can be moved
Notebooks, Point-of-Sales (POS) terminals etc.
Mobile devices are moved around all the dayPDAs, mobile phones, pagers, whatches etc.
Reference system: geometric/symbolic earth coordinates
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Device Mobility (cont'ed)
Typical projections of a device:
Position of a device is a projection to a position reference system (geometric or symbolic)
Mobility is driving force for the dynamics of this kind of projection
Ownership of a device is a projection to an identifier system
Mobility has indirect/unwanted influence on ownership: Due do thier size and weight, mobile devices may be easyly stolen or abused.
Access to mobile devices should be even better protected than to stationary devices
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User Mobility
A user is not stationary in his/her location on earth but moves around over time.
Variable speed:
Because of this movement, a comfortable size of carry-on computing devices is preferred by users
the smaller, lighter and autonomous, the better
Adapted device interaction patterns
time of the user while on the move is limited (e.g. mental capacity)
limited I/O capabilities caused by the size of the device
"proactive" cost-awareness
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User Mobility (cont'ed)
Position of a user is a projection to a position reference system (geometric or symbolic)
Mobility is driving force for the dynamics of this kind of projection, similar to Device MobilityIn practice, the user's position is approximated by the device's position
Legal setting of a user is a projection to a set of permissions or restrictions
Mobility motivates changes in legal setting, in particular if permissions are location dependent (e.g. using a mobile device in an aircraft)
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Code Mobility
A code is mobile if it is able to migrate (move) from one host to another through the network topology, e.g. from a mobile phone to a host in the wired network.
Very important issue in agent systems.
Migration is either weak (transfer of code, e.g. Java Applets) or strong (transfer of the service code and its complete state, e.g. mobile agents).
Unlike user or device mobility, code mobility is discrete.
Strong requirements on distributed life-cycle management and security.
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Service Mobility
Service Mobility is given if a user can obtain subscribed and personalized services consistently even if connected to a foreign network service provider.
Service Mobility requires
access to a service must be guaranteed (anywhere, anytime, …)
HMI, reactions, settings etc. as used by the user
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Session Mobility
Using different devices with diverse characteristics while maintaining state is called Session Mobility.
Example: Planning a journey on a PC (large screen, reliable connectivity) and use the trip data on the move on a smart mobile phone.
Challenging in Session Mobility: Maintain consistency.
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Excursion: ConsistencyLe
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Personal Mobility
A user can be globally reachable by unique personal ID and originate or receive a service session by access to any authorized terminal
Addressing needs to be service/location independent (e.g. phone call using email-address or vanity-number)
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Ad-hoc Mobility
If a device can establish a connection to devices in the vicinity without the requirement of configuration (zero-configuration) or subscribing (zero-contracting)
Fixed network part is optional
A mobile ad-hoc device may act as a router to relay a session for others
Security is a major issue
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Mode Mobility
A mode mobility aware device can switch between the infrastructure mode and the ad-hoc mode, i.e. communicate with each other via the fixed network or the ad-hoc network.
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Mobility Management
Network LayerExample: Mobile IPHeterogeneity converged into IPSupports e.g. Terminal/Ad-hoc/Mode Mobility
Application LayerExample: Session Initiation Protocol (SIP)Supports e.g.
Personal Mobility: user identification by email-addressesSession Mobility: corresponding host holds session while handover is performedService Mobility: retrieving configuration, e.g. voice mail settings
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Evolution Chain
Recapitulation: Ubiquitous Computing Evolution Chain
Remote Communicationsprotocol layering, RPC, end-to-end args ...
Fault Tolerance & Availablitytransactions, replication, load balancing ...
Managementpolicies, monitoring, managed objects ...
Remote Information Accessdistrib. file systems, distrib. databases, caching ...
Securityencryption, authentication & authorisation, PKI ...
DistributedComputing
Mobile NetworkingMobile IP, wireless networks ...
Mobile Information Accesspartial autonomy, weak connectivity & consistency ...
Adaptive Applicationsproxies, transcoding, agility ...
Position SensitivityGPS, triangulation ...
MobileComputing
UbiquitousComputing
Smart Sensors & Devicesinvisibility, ressource limitation awareness ...
Ad-hoc Networkscollaboration, zero config, rerouting ...
Context-Awarenesscontext refinement, location ...
CentralizedComputing
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Recapitulation: Mobile Computing
„Mobile Computing Paradigm“:
any service
at any place
at any time
(at any cost)
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Services
Wide range of services:
Carrier Service
Ticket Reservation Service
Transport Service
Information Service
Routing Service
…
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Device Mobility
Code Mobility
User Mobility
Session Mobility
user interaction model
smaller, battery-driven devices;multiple inhomogeneous or no networks;position becomes parameter
distributed lifecycle management;security is strong issue
issues in data distribution
What is different?
Service Usage Evolution Chain
Mobile NetworksMobile Information Access
Adaptive Applications
DistributedService Usage
MobileService Usage
UbiquitousService Usage
Ad-hoc Networks
Smart Sensors & Devices
Context-Awareness
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Conclusions
Several variations of mobility with relevance to ubiquitous computing
Mobility is a main reason for changes of the circumstances of any service interaction
A change of the position of a user (device) is relevant for many services.
A position becomes a location with further knowledge about entities in the vecinity. This enables location based services (LBS), e.g. the famous restaurant finder service.
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LBS-Example: M-Parking
Parking inspectors check online
Routing to a free parking lot
[ http://m-parking.emt.ee ]
Pay fee using mobile phone
Video!
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Is this how far UbiComp can go?