PURPOSE: To build up a cellar system of sector constitution with less interference quantity by arranging an interference station closer in a direction where an antenna gain is small.

CONSTITUTION: A same frequency channel is allocated to sectors covered by a directional antenna of a radio base station whose maximum radiation is 0° with respect to a positive direction of the s axis in which the oblique coordinate (s,t) is given as (31/2RnK, 31/2Rj), where a prescribed natural number (n), optional integral numbers j,k and a prescribed real number R. Thus, an interference station is arranged apart in a direction where an antenna gain is large and closer in a direction where the antenna gain is small so as to utilize sufficiently the directivity of a base station antenna thereby building up a cellar system with less interference quantity.