US 5,179,571 A · Spread spectrum cellular handoff apparatus and method

Abstract

An apparatus for controlling handoff in a spread-spectrum-CDMA-communications system, of radio devices moving from a cell having a base station which transmits a first spread-spectrum-communications signal with a first generic-chip-code signal, toward a different cell having a base station for transmitting a second spread-spectrum-communications signal with a second generic-chip-code signal. A radio device includes a PCN antenna, a first matched filter having an impulse response matched to the first generic-chip-code signal and a first detector for detecting the first generic-chip-code signal embedded in the first spread-spectrum-communications signal. A second matched filter has an impulse response matched to the second generic-chip-code signal and a second detector detects the second generic-chip-code signal embedded in the second spread-spectrum-communications signal. A comparator generates a comparison signal by comparing the first detected signal with the second detected signal. A receiver-message-chip-code generator generates a replica of the message-chip-code signal and a message mixer, using a replica of the message-chip-code signal, despreads the spread-spectrum-communications signal as a modulated-data signal. A synchronization circuit, based on the comparison signal being greater than a threshold, synchronizes the receiver-message-chip-code generator to the first generic-chip-code signal for receiving the first spread-spectrum-communications signal, and in response to the comparison signal being less than the threshold, synchronizes the receiver-message-chip-code generator to the second generic-chip-code signal for receiving the second spread-spectrum-communications signal. A control unit switches transmitting the message data, spread-spectrum processed with a message-chip-code signal, 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.

An apparatus for controlling handoff of radio devices moving from one cell toward an adjacent cell of a spread-spectrum-CDMA-communications system, each adjacent cell having its own generic-chip-code signal embedded in a spread-spectrum-communications signal, comprising:

a first base station for transmitting a first spread-spectrum-communications signal having a first generic-chip-code signal and message data spread-spectrum processed with a message-chip-code signal, embedded therein;
a second base station for transmitting a second spread-spectrum-communications signal having a second generic-chip-code signal embedded therein;
a radio device including,
a personal-communications-network (PCN) antenna;
a first matched filter coupled to said PCN antenna and having an impulse response matched to the first generic-chip-code signal;
a first detector coupled to said first matched filter for detecting the first generic-chip-code signal embedded in the first spread-spectrum-communications signal communicated from said first base station and outputting a first detected signal;
a second matched filter coupled to said PCN antenna and having an impulse response matched to the second generic-chip-code signal;
a second detector coupled to said second matched filter for detecting the second generic-chip-code signal embedded in the second spread-spectrum-communications signal communicated from said second base station and outputting a second detected signal;
a comparator coupled to said first detector and to said second detector for generating a comparison signal by comparing the first detected signal with the second detected signal;
a receiver-message-chip-code generator for generating a replica of the message-chip-code signal;
a message mixer coupled to said receiver-message-chip-code generator and said PCN antenna, responsive to the replica of the message-chip-code signal, for despreading the spread-spectrum-communications signal as a modulated-data signal;
a message-bandpass filter coupled to said receiver-message-mixer device for filtering the modulated-data signal;
a message detector for demodulating the modulated-data signal as received data;
a synchronization circuit coupled to said comparator and responsive to the comparison signal being greater than a threshold, for synchronizing said receiver-message-chip-code generator to the first generic-chip-code signal for receiving the first spread-spectrum-communications signal from said first base station, and responsive to the comparison signal being less than the threshold for synchronizing said receiver-message-chip-code generator to the second generic-chip-code signal for receiving the second spread-spectrum-communications signal from said second base station;
and
a control unit coupled to said first base station and said second base station and to many other base stations for switching the message data spread-spectrum processed with a message-chip-code signal, embedded in the first spread-spectrum-communications signal transmitted from said first base station, to the second spread-spectrum-communications signal transmitted from said second base station.

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Spread spectrum cellular handoff apparatus and method

Life of this patent

Spread spectrum cellular handoff apparatus and method

Life of this patent

Abstract

Claims16