Title:	AN ADAPTIVE SCHEDULING TRANSMISSION SYSTEM AN ADAPTIVE SCHEDULING TRANSMISSION SYSTEM
Author(s):	Filipe Tocha , José Sanguino , António Rodrigues
ISBN:	978-972-8924-62-1
Editors:	Jörg Roth and Jairo Gutiérrez
Year:	2008
Edition:	Single
Keywords:	Wireless Communications, Coordinated Positioning, GPS, Adaptive Scheduling
Type:	Short Paper
First Page:	139
Last Page:	143
Language:	English
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Paper Abstract:	In coordinated positioning applications all the users involved need to have real-time knowledge of each other’s positions. Due to this fact, this kind of applications generate large amounts of positioning data, which results in high costs in processing time, battery autonomy and wireless communications traffic costs. This paper describes a solution to minimize the amount of positioning data generated by each user, by using an adaptive scheduling system that analyses the user positioning dynamics to adapt the rate of transmission of positioning messages. The goal of the presented transmission scheduling system is to reduce the transmitted positioning data, reaching a compromise between the three abovementioned limitations without sacrificing the “perceived” positioning accuracy. In the coordinated positioning system used to test this scheduling system the units communicate through GPRS/UMTS/Wi-Fi and each user’s position is provided by a GPS receiver. Field trials with real data were conducted to evaluate the scheduling system performance on two different dynamic user environments: on foot and driving a car. A significant reduction (78%, 64%) of the amount of transmitted data is obtained depending on the considered environment.
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