Browse Prior Art Database

A simple distance-based update scheme to track mobile user proximities

IP.com Disclosure Number: IPCOM000033540D
Original Publication Date: 2004-Dec-15
Included in the Prior Art Database: 2004-Dec-15
Document File: 4 page(s) / 234K

Publishing Venue

Motorola

Related People

Nicolas Lhuillier: AUTHOR [+3]

Abstract

Present Geo-positioning techniques make it possible to accurately retrieve the geographical position of a mobile device, which can then be used to enable location based services. An example of such a service is to inform a user when one of their "buddies" shows up in their vicinity. However, one of the main barriers to the deployment of such a proximity service remains the cost of regularly updating positions for all of the users in the system. The optimisation of the update interval becomes a trade-off between the accuracy of the reported position and the cost in terms of the system air-time and the computing resources consumed. This paper presents a simple position updating scheme, based on distances between users and compares its efficiency, both in terms of accuracy and cost reduction, to four standard schemes using a simulation model.

This text was extracted from a Microsoft Word document.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 16% of the total text.

A simple distance-based update scheme

to track mobile user proximities

By:  Nicolas Lhuillier

Jérôme Picault

David Bourne

ABSTRACT

Present Geo-positioning techniques make it possible to accurately retrieve the geographical position of a mobile device, which can then be used to enable location based services. An example of such a service is to inform a user when one of their “buddies” shows up in their vicinity. However, one of the main barriers to the deployment of such a proximity service remains the cost of regularly updating positions for all of the users in the system. The optimisation of the update interval becomes a trade-off between the accuracy of the reported position and the cost in terms of the system air-time and the computing resources consumed. This paper presents a simple position updating scheme, based on distances between users and compares its efficiency, both in terms of accuracy and cost reduction, to four standard schemes using a simulation model.

General Terms

Algorithms, Performance, Experimentation.

Keywords

Buddy, tribe, friend, community, position, tracking, proximity.

1.     INTRODUCTION

Present geo-positioning techniques make it possible to retrieve the geographical position of a mobile device. Such functionality is performed by either using a GPS module, built-in or plugged into the mobile device, or by a network assisted algorithm based on triangulation principles (e.g. “Time Difference of Arrival”, “Enhanced Observed Time Difference”, etc.). Additional geographical information gives the opportunity for “location aware services”, in which the mobile device’s position is used to provide a better user experience by, for example, publishing information on the relevant surrounding services or customizing the services based on user’s location, etc. Additionally, the development of social groups connected via the Internet (a.k.a. virtual communities), gives the possibility for a new type of high-value service: for group members to be informed when one of their “buddies” shows up in their vicinity.

For such a proximity service to operate, the application needs to: firstly update the location for all of the group members, then to calculate the distances between each pair of members and finally to check for possible proximity. There are generally two main architectures to implement such a service: either the proximity check is performed by each device individually (distributed model) or the check is performed by a single component hosted on the network, referred to as “the server” (centralized model). In the distributed model, each device needs to retrieve all other devices’ positions (e.g. by requesting them directly). The required computation is then distributed, although it is constrained by the limited processing and memory capabilities of the small mobile devices. Hence this model mainly consumes airtime resources. In the centralized approach, the server supports the computation of distan...