a process of assigning frequencies uses propagation loss in a cdma communication system . a base station measures propagation loss over a channel between the base station and a mobile station . if the measured propagation loss is greater than a certain fixed value , the base station determines that since the mobile station is present in a position distant from the base station , the mobile station may possibly interfere with a base station of another cdma communication system . the base station assigns a frequency channel which is not adjacent to the frequency band assigned to the other cdma communication system to the mobile station .