Patent ID: 8229490
Filing Date: 2012-07-24
Classification: H04W

Abstract:
1. A hand-off control method in a radio system, wherein a radio access terminal periodically measures a reception quality of a forward link in the forward link, the radio access terminal cyclically notifies communication-destination base station identification information of a base station which is designated in the forward link, to the base station by using a first specified channel, after transmission power of the first specified channel has been set at power which is a sum between transmission power of a pilot channel and first predetermined power, and hand-off of the forward link is performed when the base station designated anew has received a first specified channel; the method comprising: allowing the radio access terminal to alter the communication-destination base station identification information to a second base station, in the first specified channel transmitted cyclically, and to transmit the first specified channel for making a request for the hand-off, after the transmission power of the first specified channel has been set at power which is a sum among the transmission power of the pilot channel, the first power and second predetermined power, when the base station of greatest forward reception power has changed from a first base station to the second base station as a result of the measurement of forward reception power levels of signals received from a plurality of base stations in the forward link, in which the radio access terminal increases the transmission power of the first specified channel in accordance with the number of times of transmissions or lapse of a time period from the hand-off request, and it sets a transmission cycle of the first specified channel to be shorter than a preceding transmission cycle, thereby to resend the first specified channel until the acknowledgement response of the first specified channel or the response of the block of the forward link comes; allowing the first base station to receive the first specified channel and to judge that the communication-destination base station identification information disagrees, so that the first base station does not transmit a block of the forward link or an acknowledgement response to the first specified channel; allowing the second base station to receive the first specified channel and to recognize that the second base station has been designated as a communication-destination base station, because of the communication-destination base station identification information of its own, so that the second base station executes a hand-off process and transmits the block of the forward link or the acknowledgement response to the first specified channel; and allowing the radio access terminal to judge that the transmission of the first specified channel containing the hand-off request has been successful, when the radio access terminal has received the block of the forward link or the acknowledgement response to the first specified channel, from the designated second base station, and to transmit the first specified channel in which the communication-destination base station identification information is designated as the second base station, in a next transmission cycle of the first specified channel, after the transmission power of the first specified channel has been returned to the power which is the sum between the transmission power of the pilot channel and the first power.