An integration of the wireless network signal strength data with the vehicle sensors information by means of a Kalman filter is proposed to estimated the relative position of each vehicle in a robot formation set. Vehicle sensors consist of wheel speed and steering angle, the WiFi data consist of reception signal strength (RSS) and the angle of the maximal RSS with respect to the robot orientation. A nonholonomic nonlinear model vehicle is considered, due to this nonlinearities a extended Kalman filter EKF is used. Simulation and experimental results of the proposed estimation strategy are presented