CDMA communications and geolocation system and method

• US 6,396,824 B1
• Filed: 09/14/1999
• Issued: 05/28/2002
• Est. Priority Date: 12/05/1990
• Status: Expired due to Fees

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Schilling, Donald L.
• Primary Examiner(s): HSU, ALPUS
• Application Number:
  US09/395,626
• Time in Patent Office: 987 Days
• Field of Search: 370/203,206,208,329,335,342 375/130,140,141,145,147,149 380/33,34,44,46 455/450,451,452,456,509,517,524,67.1,67.6
• US Class Current: 370/335
• 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 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.

2. The method of claim 1 wherein the remote chip code is a generic chip code and the remote spread spectrum signal comprises a generic chip code signal.

3. The method of claim 2 wherein the remote spread spectrum signal further comprises a remote message data signal.

4. The method of claim 3 wherein the remote message data signal is generated using a remote chip code signal mined with a data signal, the remote chip code signal time synchronized to the determined chip code timing.

5. A CDMA communication system comprising:

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.

6. The system of claim 5 wherein the remote chip code is a generic chip code and the remote spread spectrum signal comprises a generic chip code signal.

7. The system of claim 6 wherein the remote spread spectrum signal further comprises a remote message data signal.

8. The system of claim 7 wherein the remote message data signal is generated using a remote chip code signal mixed with a data signal, the remote chip code signal time synchronized to the determined chip code timing.

9. A base station for use in a CDMA communication system, the 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 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.

10. The base station of claim 9 wherein the remote chip code is a generic chip code and the remote spread spectrum signal comprises a generic chip code signal.

11. The base station of claim 10 wherein the remote spread spectrum signal further comprises a remote message data signal.

12. The base station of claim 11 wherein the remote message data signal is generated using a remote chip code signal mixed with a data signal, the remote chip code signal time synchronized to the determined chip code timing.