1. Location Information Services

2. Location Information Services:Types
Location-Transparent
Location-Tolerant
Location-Aware

3. Location-Transparent Services
Hides the effect of mobility to applications and users.
Network services and resources can be transparently accessed by means of a resource and service broker functions which map the application’s service type requests on adequate service provider instances.
Application defined quality-of-service (QoS) for the underlying network connections is sustained through a QoS manager.

4. Location-Tolerant Services
Allows applications and users to tolerate the effects of mobility that can not be hidden by the platform.
A trader function allows the application to perform a service and service type re-negotiation to achieve a graceful degradation instead of dumb service termination.
A profile handler function allows to retrieve user and terminal characteristics to perform application adaptation according to terminal type currently being used.

5. Location-Aware Services
Allows applications and users to be aware of their mobility and the absolute and real physical positions of real-world objects.
Applications can exploit this information for customizing their functionality and users can benefit from this information for navigation purposes.
This abstraction level is realized by the location information server (LIS) function that allows to query location information and to be notified about the occurrences of predefined location-related events.

6. Platform for Mobile and Location-Aware Applications
APIs
mobility
manager
mobile application platform
resource
& service
broker
QoS
location
manger
server
profile
handler
wired & wireless
networks
locating
infrastructure
mobile and location-aware
multimedia applications
mobility-management services
platform access protocols
mobility
management
signalling
protocol
generic support functions
Infrastructure and network
interfaces
Mobility Management Domain

7. Location Information Server
profile
handler
directory
database
Location information server (LIS)
event
location-aware
application
LIS API
other
midlleware
components
directory access protocol
other APIs
to remote platforms
locater
Infrastructure to locate physical objects
Acquires information about the – absolute or relative – physical location of real world objects in which an application is interested.
Hides from applications which locating technology is being used.
Has map and relationship knowledge to translate the low-level position information from the locating infrastructure into location information having meaningful abstraction level for application.
Application can query the LIS about current location of objects (LIS directory database) or can request to be notified when certain location-related conditions between objects locations are fulfilled (LIS event handler).

8. A Generic Locating Model
LIS locates objects (identified by object-ID) representing either persons or resources inside areas (identified by area-ID).
Objects have a tag (identified by tag-ID) attached to them that identifies and localizes them.
Resources can serve as tags e.g. badges, cordless telephones, PDAs, or laptops.
A LIS:
maintains relations between objects and tags.
provides graphical map in human-readable format and calculates shortest paths between areas.
finds objects that are nearest to a specified area and fulfill certain conditions.
supports both querying and notification services.
A locator provides the interface between locating infrastructure and LIS.

9. location information server
LIS Data Model
database/
event handler
application
maps
relations
position  area
sensor  area
object  tag
object  area
tag  sensor
tag  position
tag
sensor
locator
positioning system
location information server
Locating rules:
A tag is located within an area by means of sensors installed in that area. This information is collected by the locator and published to LIS, which uses a map to translate sensor-ID into area-ID.
A tag may determine its absolute geographical position (e.g. using GPS) and publish this through the locator to LIS, which uses map to translate geographical location into area-ID.

10. LIS Service Types Location retrieval service
Location-dependent object and area selection service
Event notification service
Map retrieval service
Identifier mapping service
Relationship service

11. Location Retrieval Service
Provides physical location of static/mobile object with/without tags, e.g.
In which area is person A (and when was her last sighting)?
How many (or which persons) are present in area B?
Where is equipment C (e.g. printer) in area B?

12. Location-dependent Object and Area Selection Service
Provides type or class oriented location information, e.g.
Which object of type D is present in area B?
Which one is the nearest object of type D (relative to my own location) and where it is located?
Which (nearest) area fulfils certain condition (e.g. which one is the nearest unoccupied meeting room)?

13. Event Notification Service
Avoids repeated polling the LIS by an application. This functionality is, e.g., needed to start a function on a mobile device as soon as it enters a certain area. Examples of events are
Inform me when person A enters (or leaves) area B!
Inform me when area B is empty!
Inform me next time person A meets person B anywhere!

14. Map Retrieval Service
To help users (of navigation based applications) in finding others persons, resources, or areas by providing maps and navigation instructions, e.g.
Provide me with with a (human-readable) map of area A!
Provide me with the shortest-path between area A and area B!

15. Identifier Mapping Service
Provides mappings between identifiers of areas, sensors, and positions
to support internal LIS operations,
for other support functions of mobile application platform, and
for location-aware applications operating at tag-level.

16. Relationship Service
Provides relationship information between objects and tags for applications operating at tag level instead of object level, or for applications that want to communicate with objects through its tag, e.g.
Which object is associated with tag A?
Which (if any) tag does object B posses ?
Associate tag A with objet B!

17. LIS: Implementation Issues
DBMS-based or Directory-based (such as X.500 [Maas MONET 98])
LIS do not require full functionality of DBMS
Should support distributed implementation on multiple platforms
Communication with external locator
Dramatically increases search time
Minimize the interaction with external locator using
Precise search filters
Location query optimization techniques
Event Monitoring
Active Databases