Spread spectrum conference call system and method

• US 5,263,045 A
• Filed: 10/21/1991
• Issued: 11/16/1993
• 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): Swann, Tod R.
• Application Number:
  US07/779,183
• Time in Patent Office: 757 Days
• Field of Search: 380/34, 375/1, 375/38, 455/33.1, 455/34.1, 455/59, 455/103, 379/59, 379/60
• US Class Current: 375/148
• 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 1/71 the interference being narrowband interference
• CPC Class Codes: H04B 1/7102 with transform to frequency domain
• 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 13/0022 PN, e.g. Kronecker
• CPC Class Codes: H04J 13/10 Code generation
• CPC Class Codes: H04L 7/0332 with an integrator-detector
• CPC Class Codes: H04W 4/00 Services specially adapted for wireless communication networks; Facilities therefor
• CPC Class Codes: H04W 4/12 Messaging; Mailboxes; Announcements
• 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 84/042 Public Land Mobile systems, e.g. cellular systems

Abstract

A spread spectrum communications system for use over a communications channel, including a transmitter-generic-chip-code generator, a transmitter-message-chip-code generator, an EXCLUSIVE-OR gate, a combiner, a transmitter, a receiver-generic-chip-code generator, a generic mixer, a generic-bandpass filter, a receiver-message-chip-code generator, a message mixer, a message-bandpass filter, and a synchronous detector. The transmitter-generic-chip-code generator generates a generic-chip-code signal and the transmitter-message-chip-code generator generates a message-chip-code signal. The EXCLUSIVE-OR gate spread-spectrum processes message data with the message-chip-code signal to generate a spread-spectrum signal. The combiner combines the generic-chip-code signal with the spread-spectrum signal. The transmitter transmits the combined generic-chip-code signal and spread-spectrum signal, on a carrier signal over the communications channel as a spread-spectrum-communications signal. The receiver-generic-chip-code generator generates a replica of the generic-chip-code signal. The generic mixer recovers the carrier signal from the spread-spectrum-communications signal. The receiver-message-chip-code generator generates a replica of the message-chip-code signal. The message mixer despreads the spread-spectrum-communications signal as a modulated-data signal. The tracking and acquisition circuit uses the recovered carrier signal for synchronizing the replicas of the generic-chip-code signal to the recovered carrier signal. The synchronous detector synchronously demodulates the modulated-data signal as received data.

Claims

1. A spread-spectrum conference calling communications system for simultaneously listening to a plurality of spread-spectrum channels of a spread-spectrum-communications signal comprising:

generic-spread-spectrum-processing means for recovering a carrier signal from the spread-spectrum-communications signal and for generating a replica of a generic-chip-code signal; and

a plurality of spread-spectrum receivers, each of said spread-spectrum receivers including,

acquisition means responsive to acquiring and tracking the recovered carrier signal for synchronizing said generic-spread-spectrum-processing means to the recovered carrier signal;

message-spread-spectrum-processing means for despreading the spread-spectrum-communications signal as a plurality of modulated-data signals; and

demodulation means for demodulating the modulated-data signal as a demodulated signal, said demodulation means including detection means for sequentially detecting each of the plurality of modulated-data signals as a detected signal, respectively.

2. The spread-spectrum communications system as set forth in claim 1 wherein

each of said generic-spread-spectrum-processing means includes a generic mixer for recovering the carrier signal from the spread-spectrum-communications signal;

each of said message-spread-spectrum-processing means includes a message mixer for despreading the spread-spectrum-communications signal as the modulated-data signal; and

each of said detection means includes an envelope detector for detecting the modulated-data signal as the detected signal.

3. The spread-spectrum communications system as set forth in claim 1 wherein detection means includes a synchronous detector responsive to the recovered-carrier signal for converting the modulated-data signal to the detected signal.

4. The spread-spectrum communications system as set forth in claim 3 wherein said detection means includes a synchronous detector responsive to the recovered-carrier signal for synchronously demodulating the modulated-data signal as a detected signal.

5. The spread-spectrum communications system as set forth in claim 3 wherein said detection means includes an envelope detector for converting the modulated-data signal to the detected signal.

6. A method for receiving spread-spectrum conference calls, comprising the steps of:

recovering, using a replica of a generic-chip-code signal, a carrier signal from a spread-spectrum-communications signal;

acquiring and tracking the recovered-carrier signal;

generating the replica of the generic-chip-code signal synchronized to the recovered-carrier signal;

generating a replica of the message-chip-code signal;

synchronized to the replica of the generic-chip-code signal;

despreading, using the replica of the message-chip-code signal, the spread-spectrum-communications signal as a modulated-data signal;

synchronizing the replica of the generic-chip-code signal to the recovered carrier signal; and

demodulating the modulated-data signal as received data.

7. The method as set forth in claim 6 wherein the demodulating step includes synchronously demodulating, using the recovered carrier signal, the modulated-data signal as a detected signal.

8. A spread-spectrum conference calling communications system for simultaneously listening to a plurality of spread-spectrum channels of a spread-spectrum-communications signal comprising:

generic-spread-spectrum-processing means for recovering a carrier signal from the spread-spectrum-communications signal and for generating a replica of a generic-chip-code signal; and

a plurality of spread-spectrum receivers, each of said spread-spectrum receivers including,

acquisition means responsive to acquiring and tracking the recovered carrier signal for synchronizing said generic-spread-spectrum-processing means to the recovered carrier signal;

message-spread-spectrum-processing means for despreading the spread-spectrum-communications signal as a plurality of modulated-data signals; and

demodulation means for demodulating the modulated-data signal as a demodulated signal.

9. The spread-spectrum communications system as set forth in claim 8 wherein each of said demodulation means further includes detection means for converting a modulated-data signal to a detected signal.

10. The spread-spectrum communications system as set forth in claim 9 wherein each of said demodulation means further includes bit-synchronization means for integrating and dumping the detected signal as the demodulated signal.

11. The spread-spectrum communication system as set forth in claim 10 wherein each of said plurality of spread-spectrum receivers further includes combiner means for combining each of the demodulated signals to generate a received-message signal.

12. The spread-spectrum communications system as set forth in claim 11 wherein each of said plurality of spread-spectrum receivers further includes switching means for switching the demodulation means between the message-spread-spectrum-processing means and the combining means, respectively.

13. A spread-spectrum conference calling communications system for simultaneously listening to a plurality of spread-spectrum channels of a spread-spectrum-communications signal comprising:

a receiver-generic-chip-code generator for recovering a carrier signal from the spread-spectrum-communications signal and for generating a replica of a generic-chip-code signal; and

a plurality of spread-spectrum receivers, each of said spread-spectrum receivers including,

an acquisition and tracking circuit, responsive to acquiring and tracking the recovered carrier signal, for synchronizing said receiver-generic-chip-code generator to the recovered carrier signal;

a receiver-message-chip-code generator for despreading the spread-spectrum-communications signal as a plurality of modulated-data signals; and

demodulation means for demodulating the modulated-data signal as a demodulated signal.

14. The spread-spectrum communications system as set forth in claim 13 wherein each of said demodulation means further includes a data detector for converting a modulated-data signal to a detected signal.

15. The spread-spectrum communications system as set forth in claim 14 wherein each of said demodulation means further includes a bit synchronizer for integrating and dumping the detected signal as the demodulated signal.

16. The spread-spectrum communication system as set forth in claim 15 wherein each of said plurality of spread-spectrum receivers further includes a combiner for combining each of the demodulated signals to generate a received-message signal.

17. The spread-spectrum communications system as set forth in claim 16 wherein each of said plurality of spread-spectrum receivers further includes a switch for switching the demodulation means between the receiver-message-chip-code generator and the combiner, respectively.