A system and method for accurately determining the position of a mobile unit operating within a predefined service area is disclosed. Three embodiments of the present invention are disclosed which teach the use of one, two and three narrow beam base transceiver stations in the determination of a mobile unit's position. Where one base station is utilized, an information map of signal attributes is used in the position determination. Where two and three base stations are used, signal strength measurements in combination with the time difference of arrival of a signal at the various base stations are used in the position determination.