Patent ID: 7233797

Claim:
A mobile communications system in which first and second frequencies are allocated to each wireless communications area, comprising: a first base station device provided in a first wireless communications area; a second base station device provided in a second wireless communications area; a third base station device provided in a third wireless communications area adjacent to the first and second wireless communications areas; a first base station controller controlling communications conducted by said first base station device and said third base station device; and a second base station controller controlling communications conducted by said second base station device and said third base station device, wherein each of said first, second and third base station devices can use both of the first and second frequencies to communicate with a mobile station. said first base station controller controls communications conducted by said first base station device using the first frequency and the second frequency and controls communications conducted by said third base station device using the first frequency but does not control communications conducted by said third base station device using the second frequency, said second base station controller controls communications conducted by said second base station device using the first frequency and the second frequency and controls communications conducted by said third base station device using the second frequency but does not control communications conducted by said third base station device using the first frequency, and said first base station controller allocates the same frequency to a radio channel between a mobile station and a corresponding base station device before and after the mobile station travels from the first wireless communications area to the third wireless communications area in a case where the mobile station has used the first frequency in the first wireless communications area, and allocates the first frequency to the radio channel after the mobile station travels from the third wireless communications area to the first wireless communications area.