High capacity spread spectrum channel

• US 5,166,951 A
• Filed: 05/15/1991
• Issued: 11/24/1992
• Est. Priority Date: 05/15/1991
• Status: Expired due to Term

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: SCS Mobilecom, Inc (InterDigital, Inc.)
• Inventors: Schilling, Donald L.
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US07/699,614
• Time in Patent Office: 559 Days
• Field of Search: 375/1
• US Class Current: 375/145
• CPC Class Codes: H04J 13/00 Code division multiplex systems for frequency hopping H04B1/713
• CPC Class Codes: H04L 5/02 Channels characterised by the type of signal

Abstract

A high-capacity-spread-spectrum transmitter and receiver, for use over a communications channel. A demultiplexer demultiplexes message data into a plurality of demultiplexed-data signals. A transmitter-generic-chip-code generator generates a generic-chip-code signal and a plurality of transmitter-message-chip-code generators generate a plurality of message-chip-code signals which are "near-orthogonal" over a demultiplexed data bit. A plurality of EXCLUSIVE-OR gates, spread-spectrum processes the plurality of demultiplexed-data signals with the plurality of message-chip-code signals to generate a plurality of spread-spectrum signals. A combiner combines the generic-chip-code signal and the plurality of spread-spectrum-processed signals. A receiver-generic-chip-code generator generates a replica of the generic-chip-code signal. A generic mixer recovers the carrier signal from the spread-spectrum-communications signal. A plurality of receiver-message-chip-code generators generate a plurality of replicas of the message-chip-code signals. A plurality of message mixers despreads the spread-spectrum-communications signal as a plurality of modulated-data signals. Tracking and acquisition circuits use the recovered carrier signal for synchronizing the replicas of the generic-chip-code signal to the recovered carrier signal. A plurality of envelope detectors demodulates the modulated-data signal as a plurality of received-demultiplexed data. A multiplexer multiplexes the plurality of received-multiplexed data as received data.

Claims

1. A high-capacity-spread-spectrum transmitter, handling at least spread-spectrum-signals for use with a communications channel, comprising:

demultiplexer means for demultiplexing message data into a plurality of demultiplexed-data signals;

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

a plurality of message means for generating a plurality of message-chip-code signals, wherein each message-chip-code signal is orthogonal to the other message-chip-code signals of plurality of message-chip-code signals, and is synchronized to the generic-chip-code signal;

a plurality of spreading means coupled to said demultiplexer means and said plurality of message means, respectively, for spread-spectrum processing the plurality of demultiplexed-data signals with the plurality of message-chip-code signals to generate a plurality of spread-spectrum-processed signals, respectively;

summer means for combining the generic-chip-code signal with the plurality of spread-spectrum-processed signals;

transmitter means for transmitting the combined generic-chip-code signal and plurality of spread-spectrum-processed signals, on a carrier signal over said communications channel as a spread-spectrum-communications signal.

2. The high-capacity-spread-spectrum transmitter as set forth in claim 1, wherein:

said demultiplexer means includes a demultiplexer for demultiplexing message data into a plurality of demultiplexed-data signals;

said generic means includes a transmitter-generic-chip-code generator for generating the generic-chip-code signal;

each of said message means includes a transmitter-message-chip-code generator synchronized to the generic-chip-code signal, for generating the message-chip-code signal;

each of said spreading means includes an EXCLUSIVE-OR gate for spread-spectrum processing the plurality of demultiplexed-data signals with the message-chip-code signal; and

said summer means includes a combiner for combining the plurality of generic-chip-code signals and the plurality of spread-spectrum-processed signals.

3. A high-capacity-spread-spectrum receiver, handling at least 17 spread-spectrum-processed signals, for simultaneously receiving a plurality of spread-spectrum channels of a received spread-spectrum-communications signal comprising:

a plurality of spread-spectrum receivers using a plurality of orthogonal message-chip-code signals, respectively, each of said spread-spectrum receivers including message-spread-spectrum-processing means using one of the orthogonal-message-chip-code signals for despreading the received spread-spectrum-communications signal as one of a plurality of modulated-data signals, and demodulation means for demodulating one of the modulated-data signals as one of a plurality of demodulated signals, respectively; and

multiplexer means for multiplexing the plurality of demodulated signals from said plurality of spread-spectrum receivers as received-message data.

4. The high-capacity-spread-spectrum receiver as set forth in claim 3 further including:

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

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

5. The spread spectrum receiver as set forth in claim 4 wherein

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

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

each of said demodulation means includes an envelope detector for detecting one of the plurality of modulated-data signals as one of the plurality of demodulated signals, respectively; and

said multiplexer means includes a multiplexer for multiplexing each of the plurality of demodulated signals as the received-message data.

6. The spread spectrum receiver as set forth in claim 4 wherein

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

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

each of said demodulation means includes a synchronous detector responsive to the recovered-carrier signal for converting one of the plurality of modulated-data signals to one of the plurality of detected signals, respectively;

said multiplexer means includes a multiplexer for multiplexing each of the plurality of demodulated signals as the received-message data.

7. A high-capacity-spread-spectrum receiver, handling at least 17 spread-spectrum-processed signals, for simultaneously receiving a plurality of spread-spectrum channels of a received spread-spectrum-communications signal comprising:

a plurality of spread-spectrum receivers, using a plurality of orthogonal message-chip-code signals, respectively, each of said spread-spectrum receivers including message-spread-spectrum-processing means using one of the orthogonal message-chip-code signals for despreading the respective spread-spectrum channel of the received spread-spectrum-communications signal as a modulated-data signal;

demodulation means for demodulating each of the plurality of modulated-data signals as one of the plurality of demodulated signals, respectively;

multiplexer means having a plurality of inputs for multiplexing a plurality of demodulated signals; and

switching means coupled between an input of said demodulation means and each of said message-spread-spectrum-processing means and between an output of said demodulation means and the plurality of inputs of said multiplexer means, for switching said demodulation means between each of said message-spread-spectrum-processing means and each input of said multiplexer means, respectively.

8. The high-capacity-spread-spectrum receiver as set forth in claim 7 further including:

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

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

9. The spread spectrum receiver as set forth in claim 8 wherein

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

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

each of said demodulation means includes an envelope detector for detecting one of the plurality of modulated-data signals as one of the plurality of demodulated signals, respectively; and

said multiplexer means includes a multiplexer for multiplexing each of the plurality of demodulated signals as the received-message data.

10. The spread spectrum receiver as set forth in claim 8 wherein

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

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

each of said demodulation means includes a synchronous detector responsive to the recovered-carrier signal for converting one of the plurality of modulated-data signals to one of the plurality of detected signals, respectively;

said multiplexer means includes a multiplexer for multiplexing each of the plurality of demodulated signals as the received-message data.

12. The high-capacity-spread-spectrum transmitter as set forth in claim 9 further including:

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

wherein said plurality of transmitter-message-chip-code generators is coupled to said transmitter-generic-chip-code generator with each message-chip-code signal synchronized to the generic-chip-code signal;

wherein said combiner, coupled to said generic-chip-code generator, for combining the generic-chip-code signal and the plurality of spread-spectrum-processed signals; and

wherein the transmitter transmits the combined generic-chip-code signal on a carrier signal over said spread-spectrum-communications channel as the spread-spectrum-communications signal.

11. A high-capacity-spread-spectrum transmitter, handling at least 17 spread-spectrum-processed signals, for use with a communications channel, comprising:

a demultiplexer for demultiplexing message data into a plurality of demultiplexed-data signals;

a plurality of transmitter message-chip-code generators for generating a plurality of orthogonal message-chip-code signals;

a plurality of EXCLUSIVE-OR gates coupled to said demultiplexer and to said plurality of message-chip-code generators, respectively, wherein each EXCLUSIVE-OR gate spread-spectrum processes one of the plurality of demultiplexed-data signals with a respective message-chip-code signal to generate one of a plurality of spread-spectrum-processed signals, respectively;

a combiner, coupled to said plurality of EXCLUSIVE-OR gates, for combining the plurality of spread-spectrum-processed signals;

a transmitter coupled to said combiner for transmitting the combined plurality of spread-spectrum-processed signals, on a carrier signal over said communications channel as a spread-spectrum-communications signal.

13. A high-capacity-spread-spectrum receiver, handling at least 17 spread-spectrum-processed signals, for simultaneously receiving a plurality of spread-spectrum channels of a received spread-spectrum-communications signal comprising:

a receiver-generic-chip-code generator for generating a replica of the generic-chip-code signal;

a plurality of spread-spectrum receivers, each of said spread-spectrum receivers including a receiver-message-chip-code generator for generating a message-chip-code signal, and a message mixer coupled to said receiver-message-chip-code generator and responsive to the message-chip-code signal for despreading the received spread-spectrum-communications signal as one of a plurality of modulated-data signals;

demodulation means for demodulating the plurality of modulated-data signals as a plurality of demodulated signals; and

a multiplexer for multiplexing the plurality of demodulated signals from said plurality of spread-spectrum receivers as received-message data.

14. The high-capacity-spread-spectrum receiver as set forth in claim 13, further including:

a generic mixer coupled to said receiver-generic-chip-code generator and responsive to the replica of the generic-chip-code signal for recovering a carrier signal from a spread-spectrum channel, from the received spread-spectrum-communications signal; and

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

15. The spread spectrum receiver as set forth in claim 14 wherein

each of said demodulation means includes an envelope detector for detecting the plurality of modulated-data signals as the plurality demodulated signals, respectively.

16. The spread spectrum receiver as set forth in claim 14 wherein each of said demodulation means includes a synchronous detector responsive to the recovered-carrier signal for converting the plurality of modulated-data signals to the plurality of detected signals, respectively.

17. A high-capacity-spread-spectrum receiver, handling at least 17 spread-spectrum-processed signals, for simultaneously listening to a plurality of spread-spectrum channels of a received spread-spectrum-communications signal comprising:

a plurality of spread-spectrum receivers, each of said spread-spectrum receivers including a receiver-message-chip-code generator for generating a message-chip-code signal, and a message mixer coupled to said message-chip-code generator and responsive to the message-chip-code signal for despreading the received spread-spectrum-communications signal as a modulated-data signal;

demodulation means for demodulating the plurality of modulated-data signals as a plurality of demodulated signals, respectively;

a multiplexer having a plurality of inputs for multiplexing the plurality of the demodulated signals; and

a switching circuit coupled between an input of said demodulation means and each of said message mixers and between an output of said demodulation means and the plurality of inputs of said multiplexer, for switching said demodulation means between each of said message mixers and each input of said multiplexers, respectively.

18. The spread spectrum communications system as set forth in claim 17 wherein

said demodulation means includes an envelope detector for detecting the plurality of modulated-data signals as the plurality of demodulated signals, respectively.

19. The spread spectrum communications system as set forth in claim 17 wherein

said demodulation means includes a synchronous detector responsive to the recovered-carrier signal for converting the plurality of modulated-data signals to the plurality of detected signals, respectively.

20. The high-capacity-spread-spectrum receiver as set forth in claim 17 further including:

a receiver-generic-chip-code generator for generating a replica of the generic-chip-code signal;

a generic mixer coupled to said generic-chip-code generator and responsive to the generic-chip-code signal for recovering a carrier signal for a respective spread-spectrum channel from the received spread-spectrum-communications signal; and

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

21. The spread spectrum communications system as set forth in claim 20 wherein

said demodulation means includes an envelope detector for detecting the plurality of modulated-data signals as the plurality of demodulated signals, respectively.

22. The spread spectrum communications system as set forth in claim 20 wherein

said demodulation means includes a synchronous detector responsive to the recovered-carrier signal for converting the plurality of modulated-data signals to the plurality of detected signals, respectively.

23. A method for transmitting spread spectrum conference calls, and for handling at least 17 spread-spectrum-processed signals, comprising the steps of:

demultiplexing message data as a plurality of demultiplexed-data signals;

generating a plurality message-chip-code signals;

spread-spectrum processing the plurality of demultiplexed-data signals with the message-chip-code signals, respectively, to generate a plurality of spread-spectrum-processed signals, wherein the plurality of demultiplexed-data signals and the plurality of message-chip-code signals are synchronized to the generic-chip-code signal;

combining the plurality of spread-spectrum-processed signals; and

transmitting the combined plurality of spread-spectrum-processed signals on a carrier signal over said communications channel as a spread-spectrum-communications signal.

24. A method for simultaneously listening to a plurality of spread-spectrum channels of a spread-spectrum communications signal, and for handling at least 17 spread-spectrum-processed signals, comprising the steps of:

generating, for each spread-spectrum channel, a replica of the message-chip-code signal synchronized to the replica of the generic-chip-code signal;

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

demodulating, for each spread-spectrum channel, the modulated-data signal as a demodulated signal; and

multiplexing the plurality of demodulated signals from said plurality of spread-spectrum receivers as received-message data.

25. The method a set forth in claim 24 wherein the demodulating step includes synchronously demodulating, using the recovered-carrier signal, the modulated-data signal as a detected signal.

26. The spread spectrum communications system as set forth in claim 24 wherein the demodulating step includes demodulating, using an envelope detector, the modulated-data signal as a detected signal.