Abstract: In a mobile communication system in which the service area is covered with a plurality of location registration areas each having a plurality of cells each relating to a specific base station, each location registration area has a plurality of groups so that the cells belonging to any group overlaps partly with the cells of other groups, but do not completely coincide with cells of other groups, and each mobile station belongs to one of said groups. When a mobile station moves beyond the border of location registration areas, the location updating for the mobile station is carried out at the cell in which the mobile station stays. In that case, as the mobile stations are classified into a plurality of groups, the traffic in each cell for location updating is dispersed to many cells, and the maximum traffic density for location updating per cell is reduced. So, the number of control channels in the system for location updating may be reduced.

Abstract: In a method of assigning a mobile radio communication channel, a plurality of mobile stations and a plurality of base stations constituting communication zones are distributed in a service area. The mobile stations are connected to the base stations for communication. A radio communication channel which meets the following first and second conditions is selected and assigned. The first condition is that a reception electric field level of communication between the mobile station and the base station which are connected for communication belongs to a channel group which satisfies a lower limit value. The second condition is that when the radio communication channel is used for communication connection, the ratio (D/U) of desired wave power to interference wave power satisfies quality conditions.