During the last decade, the need for highly precise positioning services, for both military and civilian applications, has grown significantly. Unfortunately, in some environments such as dense urban or indoor areas, the Global Navigation Satellite System (GNSS) suffers from poor precision and lack of satellite visibility. Therefore, another positioning
system is required to replace or augment GNSS in those environments. The use of Signals of OPportunity (SoOP) is one example of these complementary systems. Previous work explored different positioning techniques using SoOP from a wide variety of sources including; cellular phone signals, analog and digital TV, as well as audio signals. This paper
focuses on the use of WiMAX signals, which is rapidly finding its way in the military environment, as a SoOP for position estimation. The positioning technique in this work is based on the Received Signal Strength (RSS) technique. Moreover, Kalman filter will be used to improve the position estimation results of that system.