A method for calculating path loss PL at a point P in a coverage area CA of an antenna at a cell site. The method comprises the steps: transmitting a signal from the antenna, the antenna having an effective antenna gain Gant, and measuring a received signal strength indicator RSSI of the transmitted signal by a receiving antenna at the point P. The method further comprises the steps: determining a dominant indirect radiation path between the antenna and the receiving antenna to establish the effective antenna gain Gant from the antenna in a direction of the dominant indirect radiation path, and calculating path loss PL at the point P using the established effective antenna gain Gant and measured received signal strength indicator RSSI. A method for mapping a coverage area, a method for simulating changes in a communication network and a system for cell planning.