Citation

Introduction

Recently, there has been a great deal of interest in developing mobile location systems for cellular telephones. The motivation is a series of regulations passed by the Federal Communications Commission (FCC) in 1996 [1]. The purpose of these regulations is to improve the 911 service to mobile phone users. The new FCC regulations will require all cellular service providers to implement a new level of emergency call service called enhanced 911 (E911).

The final phase of E911 service must be implemented by 2001. By this date, all cellular networks must be able to determine the physical location of a mobile making a 911 call. The location system must be able to provide location estimates with an accuracy of 125 m RMS. Implementing this type of location system for an IS-95 cellular network is the focus of this paper.

Developing a reliable location system for IS-95 cellular networks is a priority. CDMA cellular systems are becoming a very popular choice for providing digital cellular and PCS service. A recent survey revealed that CDMA cellular networks are already located in 25 countries, serving over 6 million subscribers [2].

This paper investigates implementing mobile location on IS-95 CDMA systems. First, a detailed characterization of the mobile location problem is performed. Then, the accuracy of some conventional location techniques when applied to this problem are investigated and some new approaches for locating an IS-95 mobile are presented.