CSI Wave Propagation

Introduction

A propagation model for cellular signals over terrain was developed using data from the Georgia DA office consisting of signal measurements and geographical information services (GIS) maps of base station areas. This model was developed by predicting cell-signal propagation at four locations and comparing the predicted values to measured signal strengths in four given sites (labeled A, B, C, and D).

Objectives

In Phase I, a propagation model was used for predicting cell phone strength in four given cell tower locations (called sites E, F, G, and H). Phase II consisted of using this propagation model to determine the general location of the suspects at the time of the murder. The DA office can use this data as evidence in the murder trial.

Motivation

On December 15th, 2000, the high profile murder of a local police captain occurred. The primary suspects were found to have made multiple calls from cellular phones. Given data supplied from cell phone providers for the suspects' phone records and using propagation modeling, one can determine the probability that the primary suspects were in the location of the murder. Proper modeling of signal propagation over terrain will supply information to the DAs office as evidence [1].

Background

Similar propagation modeling has been done before for commercial and research purposes. Commercial telecommunications companies, such as AT&T, use propagation modeling in order to improve coverage and provide better service to customers [2]. Research into finding locations of cellular devices using signal strength has been conducted by Jian Zhu at Georgia Institute of Technology. Jian Zhu's research has been used to find 9-1-1 emergency callers' locations [3]. Dr. Greg Durgin, the aforementioned project's advisor, has also published articles on modeling path loss around various locations [4].

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