Abstract: A communication channel assignment method is disclosed in a cellular mobile communication system in which, instead of assigning communication channels in a fixed manner in each cell, whenever there is a demand for assignment of a communication channel to be used between a base station and a mobile station, channels are assigned by merely measuring the ratio of the desired signal to the interference signal at these two stations without checking interference in nearby cells and, if there is surplus in the reception level, transmission power can be lowered. In this communication channel assignment method, channels are selected in a particular order or its reverse that is identically established for all cells depending on whether the transmission power is less than or greater than a specified value.