In a method of allocating carriers of a cellular system comprising mobile stations and a wireless network of multiple base stations, multiple carriers being available for communication between base and mobile stations, the wireless network performs the following. Carriers are divided into first and second carriers, and allocated the same for each cell formed by the base stations. Each mobile station is classified as an intracell-inner-area or an intracell-outer-area mobile station. Communication is performed with the intracell-inner-area and intracell-outer-area mobile stations by the first and second carriers, respectively. A status of use of the first carriers in a first cell is measured based on communicated data, as is that of the second carriers in a second cell. The number of second carriers in the second cell is changed based on at least the status of use of the first carriers and the status of use of the second carriers.