System and method for communicating data using constant amplitude waveform with hybrid orthogonal and MSK or GMSK modulation

• US 20060251150A1
• Filed: 05/04/2005
• Published: 11/09/2006
• Est. Priority Date: 05/04/2005
• Status: Active Grant

• Current Assignee: Harris Global Communications, Inc. (L3Harris Technologies, Inc.)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Nieto, John W., Furman, William N., Wadsworth, Michael A.
• Granted Patent: US 7,352,795 B2
• Time in Patent Office: Days
• US Class Current: 375/146
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 2201/70706 with means for reducing the peak-to-average power ratio
• CPC Class Codes: H04J 13/0048 Walsh
• CPC Class Codes: H04J 13/0055 ZCZ [zero correlation zone]
• CPC Class Codes: H04L 1/0041 Arrangements at the transmitter end
• CPC Class Codes: H04L 27/2014 in which the phase changes in a piecewise linear manner during each symbol period, e.g. minimum shift keying, fast frequency shift keying H04L27/201 takes precedence
• CPC Class Codes: H04L 27/2017 in which the phase changes are non-linear, e.g. generalized and Gaussian minimum shift keying, tamed frequency modulation H04L27/201 takes precedence

Abstract

A communications system of the present invention includes a transmitter that is operative for combining an orthogonal Walsh modulation with a minimum shift keying or Gaussian minimum shift keying waveform to form a hybrid communications signal that carries communications data over a constant amplitude waveform that is spread in time and frequency. This communications signal can be transmitted to a RAKE receiver that has a plurality of correlators with output weights formed for processing this hybrid communications signal.

Claims

1. A system for communicating data, which comprises:

an encoder and interleaver circuit for encoding and interleaving communications data to be transmitted with a forward error correction code and a spread spectrum (SS) orthogonal or pseudo-orthogonal code to form a SS communications signal;

a SS orthogonal or pseudo-orthogonal modulator for receiving the encoded SS communications signal and forming a SS orthogonally or pseudo-orthogonally modulated and randomized sequence; and

a modulator circuit for modulating a minimum shift keying or Gaussian minimum shift keying waveform with the SS orthogonally modulated and randomized sequence using a specific mapping algorithm to form a communications signal having a constant amplitude waveform that is spread in time and frequency.

2. A system according to claim 1, wherein said encoder and interleaver circuit comprises a convolutional encoder and an orthogonal encoder.

3. A system according to claim 2, wherein said SS orthogonal modulator is operative for M-ary orthogonal Walsh modulation of n chips per Walsh symbol.

4. A system according to claim 3, wherein said SS orthogonal modulator is operative for modulating the communications data using a different number of orthogonal Walsh symbols.

5. A system according to claim 1, and further comprising a randomizing sequence generator for generating a binary randomizing sequence that is combined with encoded communications data.

6. A system according to claim 1, and further comprising a RAKE receiver having a plurality of correlators and output weights formed for processing the communications signal.

7. A system according to claim 1, wherein said encoder and interleaver circuit is operative for encoding with a turbo code, iterative block code, low density parity check code or Reed-Solomon code.

8. A system for communicating data, which comprises:

a transmitter for transmitting a communications signal that carries communications data, and including a convolutional encoder for encoding the communications data with a forward error correction code, an interleaver, and an orthogonal encoder for encoding the communications data from the convolutional encoder with an orthogonal code to form encoded communications data;

an orthogonal or pseudo-orthogonal modulator for receiving the encoded communications data and a binary randomizing sequence and forming an orthogonally or pseudo-orthogonally modulated, randomized and spread sequence;

a modulator circuit for modulating a minimum shift keying or Gaussian minimum shift keying waveform with the orthogonally or pseudo-orthogonally modulated, randomized and spread sequence using a specific mapping algorithm to form a communications signal having a constant amplitude waveform that is spread in time and frequency; and

a RAKE receiver for receiving the communications signal from the transmitter, and including a plurality of correlators and output weights formed for processing the communications signal.

9. A system according to claim 8, wherein said orthogonal or pseudo-orthogonal encoder is operative for M-ary orthogonal Walsh modulation of n chips per Walsh symbol.

10. A system according to claim 8, wherein said orthogonal or pseudo-orthogonal modulator is operative for modulating the communications data using a different number of orthogonal Walsh symbols.

11. A system according to claim 8, and further comprising a randomizing sequence generator for generating a binary randomizing sequence that is combined with said orthogonally modulated, spread sequence.

12. A method of communicating data, which comprises:

modulating communications data to be transmitted by combining an orthogonal Walsh modulation with a minimum shift keying or Gaussian minimum shift keying waveform using a specific mapping algorithm to form a communications signal that carries the communications data over a constant amplitude waveform that is spread in time and frequency; and

transmitting the communications signal to a receiver.

13. A method according to claim 12, which further comprises receiving the communications signal within a RAKE receiver having a plurality of correlators and output weights formed for processing the communications signal.

14. A method according to claim 12, which further comprises encoding the communications data using a convolutional encoder and an orthogonal encoder.

15. A method according to claim 12, which further comprises modulating the communications using different number of Walsh symbols.

16. A method according to claim 12, which further comprises combining an orthogonal Walsh function with a binary randomizing sequence.

17. A method according to claim 12, which further comprises encoding with a turbo code, iterative block code, low density parity check code, or Reed-Solomon code.

18. A method of communicating data, which comprises:

encoding communications data with forward error correction and orthogonal codes;

combining a specific Walsh function with a binary randomizing sequence to form an orthogonally modulated, randomized and spread sequence of the communications data;

modulating a minimum shift keying or Gaussian minimum shift keying waveform with the orthogonally modulated, randomized and spread sequence using a specific mapping algorithm to form a communications signal that carries the communications data over a constant amplitude waveform that is spread in time and frequency; and

transmitting the communications signal to a receiver.

19. A method according to claim 18, which further comprises encoding the communications data using a convolutional encoder.

20. A method according to claim 18, which further comprises selecting specific Walsh symbols from the outputs of the convolutional encoder.

21. A method according to claim 20, which further comprises using output bits from the convolutional encoder for selecting a Walsh symbol.

22. A method according to claim 18, which further comprises encoding with a rate ½

forward error correction (FEC) code.

23. A method according to claim 18, which further comprises modulating the communications using different numbers of Walsh symbols.

24. A method according to claim 18, which further comprises receiving the communications signal within a RAKE receiver having a plurality of correlators and output weights formed for processing the communications signal.