Browse Prior Art Database

Privacy Preserving Location Based Services Disclosure Number: IPCOM000015866D
Original Publication Date: 2002-Oct-06
Included in the Prior Art Database: 2003-Jun-21
Document File: 6 page(s) / 112K

Publishing Venue



This invention delivers location based service without sharing location information. Assume there are a large number of people with location

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Privacy Preserving Location Based Services

   This invention delivers location based service without sharing location information. Assume there are a large number of people with location
aware wireless devices
(e.g. GPS enabled cell phones). A single criminal individual at an establishment receiving personally identifiable information (PII data) along with current location could misuse that information and cause significant harm.

Preserving privacy requires a protocol involving several steps:

1) A spatio-temporal index must be creating associated "arrival times" with points in space. This is a multidimensional index in that arrival time(s) is(are) defined with respect to target location(s).
2) The spatio-temporal database must be populated with data. Except for the trivial case of stationary data sources (people), this involves:
i) Receiving data about traffic flow.
ii) Refining that data with a traffic model to label locations with arrival times.
3) Finally, spatio-temporal triggers are then related with locations in the database. These triggers will be used to determine who should receive the location based sevices. The triggers are related to locations and times, but not to specific individuals.

Note that steps 1-3 above may be completed without any information about specific individuals. All that is needed is data about the road network and traffic on the road network. Once this information is in place, subscribers may report their location to a service that determines if they are within the defined spatio-temporal location to receive the information. If a trigger has been set for the location, the client receives in return a "coupon" with the designated information. Note that the client need not be identified in this process (although a customer id number could be used in some embodiments of the invention).

A detailed architecture supporting Privacy Preserving Location Based Services is shown in figure 1.


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The major components of this system are discussed below

Road Network Monitor:

The Road Network Monitor received traffic flow data from some data source. Location reports containing velocity information (standard in GPS systems today) may be received anonymously. The Road Network monitor gather only data about Traffic Density as a function of location and time: ρ(x,y,t) Traffic Velocity as a function of location and time: v(x,y,t) The spatial definition of the road network itself and the speed limit as a function of location vm(x,y) The speed limit may be determined empirically from observation of the traffic flow. It is defined as the maximum velocity of traffic flow and may exceed the regulated speed limit as posted.

Flow Database with Spatio-Temporal Index and Actions (Triggers):

Data gathered or received by the Road Network Monitor is stored in the "Flow Database" using a spatio-temporal index. This may be an adaptive index such as an R-tree, an index based on a space filling curve such as a zb-tree, another spatia...