CDMA handoff arrangement and method for mobile station encountering sudden field strength variations at the boundary of adjacent cells

摘要

The CDMA base station includes a convolutional encoder 141 which encodes the signals coming from the base station controller and supplies them to the variable gain amplifier 142. The signals described above comprise a first or second control message multiplexed with the user signal in the traffic channel assigned to the mobile station. The first control message indicates that the soft handoff operation has been initiated, and the second control message indicates that the soft handoff operation is completing. The control message detector 143 is used to control the variable gain amplifier 142 such that when the first control message is encoded by the convolutional encoder, the gain of the first control message is higher than the gain of the user signal. Transmitter 150 generates a spread spectrum signal from the output of variable gain amplifier 142 for transmission to the mobile station. As a result, the first control message is sent at a power level sufficient to reach the mobile unit, otherwise the mobile station fails to receive this message when faced with a sharp decrease in field strength.