SYSTEM AND METHOD OF AN IN-BAND MODEM FOR DATA COMMUNICATIONS OVER DIGITAL WIRELESS COMMUNICATION NETWORKS

• US 20090306976A1
• Filed: 06/03/2009
• Published: 12/10/2009
• Est. Priority Date: 06/05/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Duni, Ethan R., Frank, Georg, Sgraja, Christian, Pietsch, Christian, Joetten, Christoph A., Werner, Marc W., Baik, Eugene J., Huang, Pengjun
• Granted Patent: US 8,825,480 B2
• Time in Patent Office: Days
• US Class Current: 704/214
• CPC Class Codes: G10L 19/00 Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis in musical instruments G10H
• CPC Class Codes: H04J 3/0611 PN codes H04J3/0608 takes precedence
• CPC Class Codes: H04L 25/03834 using pulse shaping
• CPC Class Codes: H04L 25/4902 Pulse width modulation; Pulse position modulation
• CPC Class Codes: H04L 5/1415 using control lines
• CPC Class Codes: H04L 5/1423 for simultaneous baseband signals
• CPC Class Codes: H04L 5/1453 of modulation type
• CPC Class Codes: H04L 7/027 extracting the synchronising or clock signal from the received signal spectrum, e.g. by using a resonant or bandpass circuit
• CPC Class Codes: H04L 7/042 Detectors therefor, e.g. correlators, state machines digital correlators in general G06F17/15

Abstract

A system is provided for transmitting information through a speech codec (in-band) such as found in a wireless communication network. A modulator transforms the data into a spectrally noise-like signal based on the mapping of a shaped pulse to predetermined positions within a modulation frame, and the signal is efficiently encoded by a speech codec. A synchronization sequence provides modulation frame timing at the receiver and is detected based on analysis of a correlation peak pattern. A request/response protocol provides reliable transfer of data using message redundancy, retransmission, and/or robust modulation modes dependent on the communication channel conditions.

Claims

1. A method of obtaining non-speech data embedded in a vocoder packet comprising:

receiving and decoding the vocoder packet;

filtering the decoded vocoder packet until a synchronization signal is detected;

calculating a timing offset based on the synchronization signal; and

extracting the non-speech data embedded in the decoded vocoder packet based on the timing offset.

2. The method of claim 1 wherein the filtering comprises:

correlating the decoded vocoder packet with a predetermined sequence to produce the synchronization signal, wherein the predetermined sequence is related to the synchronization signal; and

searching for a pattern of correlation peaks in the synchronization signal.

3. The method of claim 2 wherein the correlating comprises applying a sparse filter whose coefficients are the impulse response of the predetermined sequence.

4. The method of claim 2, wherein the searching comprises:

identifying a number of correlation peaks matching an expected pattern, wherein the expected pattern is based on a combination of negative and positive correlation peaks;

calculating a sum of the number of positive correlation peaks and the number of negative correlation peaks; and

determining if the sum is greater than a predetermined value.

5. The method of claim 4 wherein the predetermined value is 80% of the maximum number of positive correlation peaks and negative correlation peaks found in the synchronization signal which meet the expected pattern.

6. The method of claim 2, wherein the searching comprises:

identifying a number of positive correlation peaks in the synchronization signal;

determining if the time distance between the positive correlation peaks is within a first predetermined range; and

determining if the positive correlation peaks amplitude is greater than a first predetermined threshold.

7. The method of claim 2, wherein the searching comprises:

identifying a number of negative correlation peaks in the synchronization signal;

determining if the time distance between the negative correlation peaks is within a second predetermined range; and

determining if the negative correlation peaks amplitude is greater than a second predetermined threshold.

8. The method of claim 1, wherein the calculating comprises adding the time distance between a positive correlation peak and a reference time instance to the time distance between the positive correlation peak and a negative correlation peak.

9. The method of claim 1, wherein the calculating comprises adding the time distance between a negative correlation peak and a reference time instance.

10. The method of claim 1 wherein the extracting comprises:

determining a demodulation frame boundary based on the timing offset;

determining a demodulation type based on a demodulation type indicator;

determining a data signal pulse position using the demodulation frame boundary and the demodulation type; and

calculating an output data symbol based on the data signal pulse position.

11. The method of claim 10 wherein the demodulation type indicator is a predetermined signal.

12. The method of claim 11 wherein the predetermined signal is a sinusoidal signal.

13. The method of claim 11 wherein the predetermined signal is stored in a memory at a position determined by the timing offset.

14. A memory storing a computer program that, when executed, causes a computer to perform the acts of:

receiving and decoding a vocoder packet;

filtering the decoded vocoder packet until a synchronization signal is detected;

calculating a timing offset based on the synchronization signal; and

extracting the non-speech data embedded in the decoded vocoder packet based on the timing offset.

15. An apparatus comprising:

a receiver configured to receive and decode a vocoder packet;

a filter configured to filter the decoded vocoder packet until a synchronization signal is detected;

a calculator configured to calculate a timing offset based on the synchronization signal; and

an extractor configured to extract non-speech data embedded in the decoded vocoder packet based on the timing offset.

16. The apparatus of claim 15, wherein the filter comprises:

a correlator to correlate the decoded vocoder packet with a predetermined sequence to produce the synchronization signal, wherein the predetermined sequence is related to the synchronization signal; and

a searcher to search for a pattern of correlation peaks in the synchronization signal.

17. The apparatus of claim 16, wherein the correlator is a sparse filter whose coefficients are the impulse response of the predetermined sequence.

18. The apparatus of claim 16, wherein the searcher comprises:

a peak identifier for identifying a number of correlation peaks matching an expected pattern, wherein the expected pattern is based on a combination of negative and positive correlation peaks;

a peak calculator for calculating a sum of the number of positive correlation peaks and the number of negative correlation peaks; and

a peak sum comparator for determining if the sum is greater than a predetermined value.

19. The apparatus of claim 18 wherein the predetermined value is 80% of the maximum number of positive correlation peaks and negative correlation peaks found in the synchronization signal which meet the expected pattern.

20. The apparatus of claim 16 wherein the searcher comprises:

a positive peak detector to identify the number of positive correlation peaks in the synchronization signal;

a positive peak time comparator to determine if the time distance between the positive correlation peaks is within a first predetermined range; and

a positive peak amplitude comparator to determine if the positive correlation peaks amplitude is greater than a first predetermined threshold.

21. The apparatus of claim 16 wherein the searcher comprises:

a negative peak detector to identify the number of negative correlation peaks in the synchronization signal;

a negative peak time comparator to determine if the time distance between the negative correlation peaks is within a second predetermined range; and

a negative peak amplitude comparator to determine if the negative correlation peaks amplitude is greater than a second predetermined threshold.

22. The apparatus of claim 15, wherein the calculator comprises an adder to add the time distance between a positive correlation peak and a reference time instance to the time distance between the positive correlation peak and a negative correlation peak.

23. The apparatus of claim 15, wherein the calculator comprises an adder to add the time distance between a negative correlation peak and a reference time instance.

24. The apparatus of claim 15 wherein the extractor comprises a processor to:

determine a demodulation frame boundary based on the timing offset;

determine a demodulation type based on a demodulation type indicator;

determine a data signal pulse position using the demodulation frame boundary and the demodulation type; and

calculate an output data symbol based on the data signal pulse position.

25. An apparatus comprising:

means for receiving and decoding a vocoder packet;

means for filtering the decoded vocoder packet until a synchronization signal is detected;

means for calculating a timing offset based on the synchronization signal; and

means for extracting the non-speech data embedded in the decoded vocoder packet based on the timing offset.

26. The apparatus of claim 25, wherein the means for filtering comprises:

means for correlating the decoded vocoder packet with a predetermined sequence to produce the synchronization signal, wherein the predetermined sequence is related to the synchronization signal; and

means for searching for a pattern of correlation peaks in the synchronization signal.

27. The apparatus of claim 26, wherein the means for correlating is further configured to apply a sparse filter whose coefficients are the impulse response of the predetermined sequence.

28. The apparatus of claim 26, wherein the means for searching is further configured to:

identify a number of correlation peaks matching an expected pattern, wherein the expected pattern is based on a combination of negative and positive correlation peaks;

calculate a sum of the number of positive correlation peaks and the number of negative correlation peaks; and

determine if the sum is greater than a predetermined value.

29. The apparatus of claim 28, wherein the predetermined value is 80% of the maximum number of positive correlation peaks and negative correlation peaks found in the synchronization signal which meet the expected pattern.

30. The apparatus of claim 26, wherein the means for searching is further configured to:

identify a number of positive correlation peaks in the synchronization signal;

determine if the time distance between the positive correlation peaks is within a first predetermined range; and

determine if the positive correlation peaks amplitude is greater than a first predetermined threshold.

31. The apparatus of claim 26, wherein the means for searching is further configured to:

identify a number of negative correlation peaks in the synchronization signal;

determine if the time distance between the negative correlation peaks is within a second predetermined range; and

determine if the negative correlation peaks amplitude is greater than a second predetermined threshold.

32. The apparatus of claim 25, wherein the means for calculating comprises means for adding the time distance between a positive correlation peak and a reference time instance to the time distance between the positive correlation peak and a negative correlation peak.

33. The apparatus of claim 25, wherein the means for calculating comprises means for adding the time distance between a negative correlation peak and a reference time instance.

34. The apparatus of claim 25 wherein the means for extracting comprises:

means for determining a demodulation frame boundary based on the timing offset;

means for determining a demodulation type based on a demodulation type indicator;

means for determining a data signal pulse position using the demodulation frame boundary and the demodulation type; and

means for calculating an output data symbol based on the data signal pulse position.