CDMA communications and geolocation system and method

• US 5,506,864 A
• Filed: 09/23/1994
• Issued: 04/09/1996
• Est. Priority Date: 12/05/1990
• Status: Expired due to Term

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Schilling, Donald L.
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US08/311,773
• Time in Patent Office: 564 Days
• Field of Search: 375/1, 375/205, 342/450, 342/457
• US Class Current: 370/342
• CPC Class Codes: G01S 13/82 wherein continuous-type signals are transmitted
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 1/71 the interference being narrowband interference
• CPC Class Codes: H04B 1/7102 with transform to frequency domain
• CPC Class Codes: H04B 2201/70701 featuring pilot assisted reception
• CPC Class Codes: H04B 2201/709709 Methods of preventing interference
• CPC Class Codes: H04B 7/18547 for geolocalisation of a station position fixing by direction or distance determination G01S5/00
• CPC Class Codes: H04B 7/216 Code division or spread-spectrum multiple access [CDMA, SSMA]
• CPC Class Codes: H04B 7/2628 using code-division multiple access [CDMA] or spread spectrum multiple access [SSMA] H04B7/2618 takes precedence
• CPC Class Codes: H04B 7/2631 for broadband transmission
• CPC Class Codes: H04J 13/00 Code division multiplex systems for frequency hopping H04B1/713
• CPC Class Codes: H04W 4/12 Messaging; Mailboxes; Announcements
• CPC Class Codes: H04W 4/18 Information format or content conversion, e.g. adaptation by the network of the transmitted or received information for the purpose of wireless delivery to users or terminals
• CPC Class Codes: H04W 52/343 taking into account loading or congestion level
• CPC Class Codes: H04W 52/346 distributing total power among users or channels
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 64/006 with additional information processing, e.g. for direction or speed determination
• CPC Class Codes: H04W 88/02 Terminal devices
• CPC Class Codes: H04W 88/08 : Access point devices

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.

Claims

1. A spread-spectrum communications and geolocation system for communicating message data comprising:

first generic means for generating a generic-chip-code signal;

spreading means for spread-spectrum processing the message data, synchronized with the generic chip-code signal, as spread-spectrum-processed-message data;

combiner means for combining the generic-chip-code signal with the spread-spectrum-processed-message data, thereby generating a code-division-multiple-access (CDMA) signal;

transmitter means for transmitting, using radio waves traversing free space, the CDMA signal over a communications channel;

detection means, coupled to said communications channel, for detecting the generic-chip-code signal embedded in the CDMA signal, said detection means including,

receiving means for receiving the CDMA signal;

second generic means, coupled to said receiving means, for detecting the generic-chip-code signal embedded in the CDMA signal and for generating a replica of the generic-chip-code signal; and

despreading means, synchronized with the replica of the generic-chip-code signal, for despreading the spread-spectrum-processed-message data as a despread signal;

data detection means, synchronized with the replica of the generic-chip-code signal, for detecting message data in the despread signal; and

range means, responsive to the detected-generic-chip-code signal and the replica of the generic-chip-code signal, for determining a range delay between the transmitter means and the receiving means.

2. The spread-spectrum communications and geolocation system as set forth in claim 1 with said despreading means including:

a message-chip-code generator for generating a message-chip-code signal synchronized to the replica of the generic-chip-code signal;

a product detector for mixing the message-chip-code signal with a received CDMA signal to generate a detected spread-spectrum signal; and

a bandpass filter for filtering the detected spread-spectrum signal; and

said data detection means includes a data detector, synchronized with the replica of the generic-chip-code signal, for detecting message data in the detected spread-spectrum signal.

3. A spread-spectrum communications and geolocation system for communicating message data comprising:

a generic-chip-code generator for generating a generic-chip-code signal;

a spread-spectrum modulator for spread-spectrum processing the message data, synchronized with the generic-chip-code signal, as spread-spectrum-processed-message data;

a combiner for combining the generic-chip-code signal with the spread-spectrum-processed-message data, thereby generating a code-division-multiple-access (CDMA) signal;

a transmitter for transmitting, using radio waves traversing free space, the CDMA signal over a communications channel;

a detector, coupled to said communications channel, for detecting the generic-chip-code signal embedded in the CDMA signal, said detector including,

a receiver-generic-chip-code generator, synchronized to the detected-generic-chip-code signal, for generating a replica of the generic-chip-code signal;

a message-chip-code generator for generating, synchronized to the replica of the generic-chip-code signal, a message-chip-code signal;

a product detector for mixing the message-chip-code signal with a received CDMA signal to generate a detected spread-spectrum signal;

a bandpass filter for filtering the detected spread-spectrum signal;

a data detector, synchronized with the replica of the generic-chip-code signal, for detecting message data in the detected spread-spectrum signal; and

a range delay circuit, responsive to timing between the detected-generic-chip-code signal and the replica of the generic-chip-code signal, for determining a range between the transmitter and the detector.

4. A spread-spectrum communications and geolocation method for communicating message data, comprising the steps of:

generating a generic-chip-code signal;

synchronizing the message data with the generic-chip-code signal;

spread-spectrum processing the message data as a spread-spectrum-processed-message data;

combining the generic-chip-code signal with the spread-spectrum-processed-message data, thereby generating a code-division-multiple-access (CDMA) signal;

transmitting, using radio waves traversing free space, the CDMA signal from a transmitter over a communications channel;

detecting, from the communications channel on a receiver, the generic-chip-code signal embedded in the CDMA signal;

generating, synchronized to the detected-generic-chip-code signal, a replica of the generic-chip-code signal;

generating, synchronized to the replica of the generic-chip-code signal, a message-chip-code signal;

mixing the message-chip-code signal with a received CDMA signal to generate a detected spread-spectrum signal;

filtering the detected spread-spectrum signal;

detecting, synchronized to the replica of the generic-chip-code signal, message data in the detected spread-spectrum signal; and

determining, using the detected-generic-chip-code signal and the replica of the generic-chip-code signal, a range between the transmitter and the receiver.

5. A spread-spectrum communications and geolocation method for communicating message data and determining range between a remote unit and a base station, comprising the steps of:

generating a base-generic-chip-code signal;

synchronizing base message data with the base-generic-chip-code signal;

spread-spectrum processing the base message data as a spread-spectrum-processed-message data;

combining the base-generic-chip-code signal with the spread-spectrum-processed-message data, thereby generating a code-division-multiple-access (CDMA) signal;

transmitting, using radio waves traversing free space, the CDMA signal from the base station over a communications channel;

detecting, from the communications channel at the remote unit, the base-generic-chip-code signal embedded in the CDMA signal;

recovering, at the remote unit, the base message data communicated from the base station;

generating, at the remote unit, synchronized with the detected-base-generic-chip-code signal, a remote-generic-chip-code signal;

spread-spectrum processing remote message data as a spread-spectrum-processed-remote message data;

combining the remote-generic-chip-code signal with the spread-spectrum-processed-remote message data, thereby generating a remote code-division-multiple-access (CDMA) signal;

transmitting, using radio waves traversing free space, the remote CDMA signal from the remote unit over a communications channel;

detecting, at the base station, the remote-generic-chip-code signal embedded in the remote CDMA signal;

recovering, at the base station, the remote message data communicated from the remote unit; and

comparing a timing between the base-generic-chip-code signal and the detected remote-generic-chip-code signal to determine a range between the base station and the remote unit.

6. A spread-spectrum communications and geolocation method for communicating message data and determining range between a remote unit and a base station, comprising the steps of:

generating a base-generic-chip-code signal;

synchronizing base message data with the base-generic-chip-code signal;

spread-spectrum processing the base message data as a spread-spectrum-processed-message data;

combining the base-generic-chip-code signal with the spread-spectrum-processed-message data, thereby generating a code-division-multiple-access (CDMA) signal;

transmitting, using radio waves traversing free space, the CDMA signal from the base station over a communications channel;

detecting, from the communications channel at the remote unit, the base-generic-chip-code signal embedded in the CDMA signal;

recovering, at the remote unit, the base message data communicated from the base station;

spread-spectrum processing remote message data as a spread-spectrum-processed-remote message data;

combining the detected base-generic-chip-code signal with the spread-spectrum-processed-remote message data, thereby generating a remote code-division-multiple-access (CDMA) signal having a relayed detected-base-generic-chip-code signal;

transmitting, using radio waves traversing free space, the remote CDMA signal from the remote unit over a communications channel;

detecting, at the base station, the relayed-detected-base-generic-chip-code signal embedded in the remote CDMA signal;

recovering, at the base station, the remote message data communicated from the remote unit; and

comparing a timing between the base-generic-chip-code signal and the relayed-detected-base-generic-chip-code signal to determine a range between the base station and the remote unit.