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Abstract

An apparatus for controlling hand-off in a spread-spectrum-CDMA-communications system, for radio devices moving from one cell to another, with each cell having a base station transmitting spread spectrum signals with generic-chip-code signals. A radio device includes a cellular antenna, matched filters, and detectors for detecting generic-chip-code signals embedded in spread-spectrum-communications signals. A comparator generates a comparison signal by comparing the relative time of arrival of a second detected signal with a first detected signal. A receiver-message-chip-code generator generates a replica of the message-chip-code signal, and a message mixer despreads the spread-spectrum-communications signal. A synchronization circuit synchronizes the receiver-message-chip-code generator to the first generic-chip-code signal for receiving the first spread-spectrum-communications signal or to the second generic-chip-code signal for receiving the second spread-spectrum communications signal, depending on a threshold. A control unit switches transmitting the message data, embedded in the first spread-spectrum-communications signal from the first base station, to the second spread-spectrum-communications signal transmitted from the second base station. Hand-off from an analog base station to a second base station utilizing spread spectrum is also possible.

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First Claim