In this paper the authors present the localization system which uses triangulation and trilateration to position mobile robot in the two-dimensional space. Distance was measured with the strength of radio signal emitted by devices of existing communication network, which were constructed by the authors. To get the actual distance in the function of radio signal strength the calibration curve, which was set empirically, made from the spline of linear functions was used. Research in this paper can be divided into two parts: the quality tests of communication and the localization using radio waves. Quantity measure of the correctly transmitted frames showed that the communication network works with the credibility of 80%, which is good result for the radio waves. Outcome of the localization quality showed that the position error did not surpass 1.7 m, which is a good result compared to the error of a typical GPS receiver is 15 m. Summing up, the localization system proposed by the authors is working well. Furthermore the test showed that triangulation and trilateration are universal methods of positioning and they can be used in other systems. Additionally the test indicated that the accuracy can by increased by using devices with a better signal strength measure.