Abstract: A CDMA mobile communication system carries out a method of controlling an intersystem hand-off by subtracting a margin value from a pilot signal strength of another system. A detector detects information in a report from the mobile station, representing the signal strength of the pilot signal from the base station. A changer subtracts a corresponding margin value from the detected pilot signal strength, thereby changing the pilot signal strength. The executing unit executes an intersystem hand-off to the other system if the pilot signal strength changed by the changing means exceeds a predetermined threshold value.

Abstract: A transmission power control system for controlling, with a mobile station and two or more base stations simultaneously connectable to the mobile station base stations and transmission power from the base stations to the mobile station, including a control device for determining on a base station to be handed off based on information about a transmission strength of a pilot signal which each of the base stations transmits to the mobile station and information about strength of the pilot signal received at the mobile station which is transmitted by the base station to control transmission power before and after handoff.

Abstract: In a hand-off method in a CDMA cellular system, whether a frequency in use is a frequency layer boundary is determined in response to a notification indicating a deterioration in the frequency in use from a mobile unit. A frequency prepared in both a communication cell and an adjacent cell is selected when the frequency in use is the frequency layer boundary. Inter-frequency hand-off is executed in the communication cell by using the selected frequency. Inter-cell hand-off is executed in response to a notification indicating a destination cell from the mobile unit, which is based on a pilot signal strength measurement result from the adjacent cell.

Abstract: To expedite handoff control while a mobile unit moves between first and neighboring second cells, A and B frequencies are assigned for traffic communication to a first base station and only B frequency is assigned for traffic communication to a second base station, and both of the base stations are connected to a control station, where the first base station is assigned to the first cell and the second base station is assigned to the second cell. The mobile unit has been assigned A frequency in the first base station, and the second base station is accompanied by a pilot transmitting device for transmitting only a pilot signal on the A frequency. As soon as it is informed of deterioration in a field intensity of the frequency at the mobile unit together with pilot information specific to the pilot signal from the first base station, the control station makes a determination that the mobile unit is approaching the second base station, and deals with a handoff from the A frequency to the B frequency.