CDMA communications and geolocation system and method
First Claim
1. A method for making a range determination between a remote unit and a base station within a CDMA communication system, the method comprising:
- generating a base generic chip code signal and a base message chip code signal;
mixing the base message chip code signal with a data signal as a base data message signal;
combining the base generic chip code signal and the base data message signal as a base spread spectrum signal;
transmitting the base spread spectrum signal from the base station;
receiving the base spread spectrum signal at the remote unit;
determining a chip code timing of the received base spread spectrum signal using the generic chip code signal;
recovering data from the received base spread spectrum signal using the determined chip code timing and the message chip code signal;
transmitting from the remote unit a remote spread spectrum signal having a remote chip code time synchronized to the determined chip code timing;
receiving the remote spread spectrum signal at the base station; and
determining a range between the base station and the remote unit using a time difference between the base generic chip code signal as generated at the base station and the received remote spread spectrum signal.
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Accused Products
Abstract
A spread-spectrum CDMA communications system for locating remote units, and for communicating message data between a plurality of remote units and a base station. The spread-spectrum CDMA communications system includes a plurality of base stations and a plurality of remote units. A base station has a spread-spectrum modulator for spread-spectrum processing the message data, and a transmitter for transmitting the spread-spectrum processed-message data, combined with a generic-chip-code signal, from the base station to a remote unit. The base station also has an antenna, and spread-spectrum detectors for recovering message-data communicated from the remote units. A remote unit has an antenna, and a detector coupled to the antenna for recovering data communicated from the base station. The detector includes a spread spectrum demodulator. Also, the remote unit has a device for converting the format of the data into a form suitable for communicating over radio waves, a spread spectrum modulator and a transmitter. The base station has a range circuit, which comparers the generic-chip-code signal generated at the base station with the generic-chip-code signal received from the remote unit, for determining a range between the remote unit and the base station.
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Citations
12 Claims
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1. A method for making a range determination between a remote unit and a base station within a CDMA communication system, the method comprising:
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generating a base generic chip code signal and a base message chip code signal;
mixing the base message chip code signal with a data signal as a base data message signal;
combining the base generic chip code signal and the base data message signal as a base spread spectrum signal;
transmitting the base spread spectrum signal from the base station;
receiving the base spread spectrum signal at the remote unit;
determining a chip code timing of the received base spread spectrum signal using the generic chip code signal;
recovering data from the received base spread spectrum signal using the determined chip code timing and the message chip code signal;
transmitting from the remote unit a remote spread spectrum signal having a remote chip code time synchronized to the determined chip code timing;
receiving the remote spread spectrum signal at the base station; and
determining a range between the base station and the remote unit using a time difference between the base generic chip code signal as generated at the base station and the received remote spread spectrum signal. - View Dependent Claims (2, 3, 4)
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5. A CDMA communication system comprising:
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a base station comprising;
means for generating a base generic chip code signal and a base message chip code signal;
means for mixing the base message chip code signal with a data signal as base data message signal;
means for combining the base generic chip code signal and the base data message signal as a base spread spectrum signal; and
means for transmitting the base spread spectrum signal;
means for receiving a remote spread spectrum signal at the base station; and
means for determining a range between the base station and a remote unit using a time difference between the base generic chip code signal as generated and the received remote spread spectrum signal; and
the remote unit comprising;
means for receiving the base spread spectrum signal;
means for determining a chip code timing of the received base spread spectrum signal using the generic chip code signal;
means for recovering data from the received base spread spectrum signal using the determined chip code timing and the message chip code signal; and
means for transmitting a remote spread spectrum signal having a remote chip code time synchronized to the determined chip code timing from the remote unit. - View Dependent Claims (6, 7, 8)
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9. A base station for use in a CDMA communication system, the base station comprising:
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means for generating a base generic chip code signal and a base message chip code signal;
means for mixing the base message chip code signal with a data signal as a base data message signal;
means for combining the base generic chip code signal and the base data message signal as a base spread spectrum signal; and
means for receiving a remote spread spectrum signal, the remote spread spectrum signal transmitted from a remote unit and transmitted having a remote chip code signal time synchronized to a generic chip code signal component of the base spread spectrum signal as received at the remote unit; and
means for determining a range between the base station and the remote unit using a time difference between the base generic chip code signal as generated and the received remote spread spectrum signal. - View Dependent Claims (10, 11, 12)
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Specification