Method and apparatus for low complexity compression of signals employing differential operation for transient segment detection

• US 9,356,731 B2
• Filed: 02/27/2015
• Issued: 05/31/2016
• Est. Priority Date: 09/10/2010
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Baheti, Pawan Kumar, Garudadri, Harinath, Chi, Yuejie
• Primary Examiner(s): PULLIAS, JESSE SCOTT
• Application Number:
  US14/634,117
• Publication Number:
  US 20150171998A1
• Time in Patent Office: 459 Days
• Field of Search: 704200-230, 704500-504
• US Class Current: 1/1
• CPC Class Codes: H03M 7/30 Compression speech analysis-synthesis for redundancy reduction G10L19/00; for image communication H04N; Expansion; Suppression of unnecessary data, e.g. redundancy reduction
• CPC Class Codes: H04L 1/0043 Realisations of complexity reduction techniques, e.g. use of look-up tables
• CPC Class Codes: H04L 1/0052 Realisations of complexity reduction techniques, e.g. pipelining or use of look-up tables
• CPC Class Codes: H04L 1/22 using redundant apparatus to increase reliability

Abstract

Certain aspects of the present disclosure relate to techniques for low-complexity encoding (compression) of broad class of signals, which are typically not well modeled as sparse signals in either time-domain or frequency-domain. First, the signal can be split in time-segments that may be either sparse in time domain or sparse in frequency domain, for example by using absolute second order differential operator on the input signal. Next, different encoding strategies can be applied for each of these time-segments depending in which domain the sparsity is present.

Claims

1. An apparatus for communication, comprising:

a sensor configured to generate a biophysical signal of a subject for monitoring the health of the subject;

a first circuit configured to perform a differential operation on a biophysical signal to detect one or more transient segments of the biophysical signal;

a second circuit configured to estimate a residual segment of the biophysical signal based on the one or more transient segments;

a first encoder configured to encode the one or more transient segments;

a second encoder configured to encode the residual segment; and

a transmitter configured to transmit the one or more encoded transient segments and the encoded residual segment to an aggregator, which generates information related to the health of the subject based on the one or more encoded transient segments and the encoded residual segment.

2. The apparatus of claim 1, wherein the differential operation on the signal comprises a second-order differential on the biophysical signal to detect the one or more transient segments.

3. The apparatus of claim 2, wherein the first circuit is also configured to:

identify at least one sample of the biophysical signal having a value of the second-order differential larger than a threshold; and

select a window of samples of the biophysical signal around each of the at least one sample to detect the one or more transient segments.

4. The apparatus of claim 1, wherein the first encoder is also configured to encode the transient segments by encoding segments of the biophysical signal being sparse in the time domain.

5. The apparatus of claim 4, wherein encoding the segments of the biophysical signal being sparse in the time domain comprises sensing inflection points of the biophysical signal.

6. The apparatus of claim 1, wherein the second circuit is also configured to:

replace, in the biophysical signal, samples of the transient segments with values to estimate the residual segment.

7. The apparatus of claim 1, wherein the second encoder is also configured to:

perform, in the time domain, random sampling of the residual segment to encode the residual segment.

8. The apparatus of claim 1, wherein the second encoder is also configured to:

determine whether the residual segment comprises a low-pass signal; and

perform decimation on the residual segment, if the residual segment comprises the low-pass signal.

9. The apparatus of claim 8, further comprising:

a finite impulse response (FIR) filter configured to filter the residual segment prior to the decimation.

10. The apparatus of claim 1, wherein the second encoder is also configured to:

determine whether the residual segment comprises a low-pass signal; and

perform random sampling of the residual segment, if the residual segment does not comprise the low-pass signal.

11. The apparatus of claim 1, wherein the biophysical signal comprises a photoplethysmograph (PPG) signal.

12. The apparatus of claim 11, wherein the sensor is configured to generate the PPG signal by sensing a biophysical parameter in an ear of the subject.

13. The apparatus of claim 11, wherein the sensor is configured to generate the PPG signal by sensing a biophysical parameter in a finger of the subject.

14. The apparatus of claim 11, wherein the sensor comprises a pulse oximeter sensor configured to generate the PPG signal.

15. The apparatus of claim 1, wherein the biophysical signal comprises an electro cardiogram (ECG) signal.

16. The apparatus of claim 1, wherein the sensor comprises an accelerometer sensor configured to generate the biophysical signal related to motion of the subject.

17. A method for communication, comprising:

generating a biophysical signal by sensing a biophysical parameter of a subject for monitoring the health of the subject;

performing a differential operation on a signal to detect one or more transient segments of the signal;

estimating a residual segment of the signal based on the one or more transient segments;

encoding the one or more transient segments;

encoding the residual segment; and

transmitting the one or more encoded transient segments and the encoded residual segment to an aggregator, which generates information related to the health of the subject based on the one or more encoded transient segments and the encoded residual segment.

18. The method of claim 17, wherein performing the differential operation on the signal comprises applying a second-order differential on the biophysical signal to detect the one or more transient segments.

19. The method of claim 18, further comprising:

identifying at least one sample of the biophysical signal having a value of the second-order differential larger than a threshold; and

selecting a window of samples of the biophysical signal around each of the at least one sample to detect the one or more transient segments.

20. The method of claim 17, wherein encoding the transient segments comprises:

encoding segments of the biophysical signal being sparse in the time domain.

21. The method of claim 20, wherein encoding the segments of the biophysical signal being sparse in the time domain comprises sensing inflection points of the signal.

22. The method of claim 17, further comprising:

replacing, in the biophysical signal, samples of the transient segments with values to estimate the residual segment.

23. The method of claim 17, wherein encoding the residual segment comprises:

performing, in the time domain, random sampling of the residual segment.

24. The method of claim 17, wherein encoding the residual segment comprises:

determining whether the residual segment comprises a low-pass signal; and

performing decimation on the residual segment, if the residual segment comprises the low-pass signal.

25. The method of claim 24, further comprising:

finite impulse response (FIR) filtering of the residual segment prior to the decimation.

26. The method of claim 17, wherein encoding the residual segment comprises:

determining whether the residual segment comprises a low-pass signal; and

performing random sampling of the residual segment, if the residual segment does not comprise the low-pass signal.

27. An apparatus for communication, comprising:

means for generating a biophysical signal by sensing a biophysical parameter of a subject for monitoring the health of the subject;

means for performing a differential operation on a signal to detect one or more transient segments of the signal;

means for estimating a residual segment of the signal based on the one or more transient segments;

means for encoding the one or more transient segments;

means for encoding the residual segment; and

means for transmitting the one or more encoded transient segments and the encoded residual segment to an aggregator, which generates information related to the health of the subject based on the one or more encoded transient segments and the encoded residual segment.

28. The apparatus of claim 27, wherein the means for performing the differential operation comprises means for applying a second-order differential on the biophysical signal to detect the one or more transient segments.

29. The apparatus of claim 28, further comprising:

means for identifying at least one sample of the biophysical signal having a value of the second-order differential larger than a threshold; and

means for selecting a window of samples of the biophysical signal around each of the at least one sample to detect the one or more transient segments.

30. The apparatus of claim 27, wherein the means for encoding the transient segments comprises:

means for encoding segments of the biophysical signal being sparse in the time domain.

31. The apparatus of claim 30, wherein the means for encoding the segments of the biophysical signal being sparse in the time domain comprises:

means for sensing inflection points of the biophysical signal.

32. The apparatus of claim 27, further comprising:

means for replacing, in the biophysical signal, samples of the transient segments with values to estimate the residual segment.

33. The apparatus of claim 27, wherein the means for encoding the residual segment comprises:

means for performing, in the time domain, random sampling of the residual segment.

34. The apparatus of claim 27, wherein the means for encoding the residual segment comprises:

means for determining whether the residual segment comprises a low-pass signal; and

means for performing decimation on the residual segment, if the residual segment comprises the low-pass signal.

35. The apparatus of claim 27, wherein the means for encoding the residual segment comprises:

means for determining whether the residual segment comprises a low-pass signal; and

means for performing random sampling of the residual segment, if the residual segment does not comprise the low-pass signal.

36. A computer-program product for communication, comprising a non-transitory computer-readable medium comprising instructions executable to:

generate a biophysical signal by sensing a biophysical parameter of a subject for monitoring the health of the subject

perform a differential operation on a signal to detect one or more transient segments of the signal;

estimate a residual segment of the signal based on the one or more transient segments;

encode the one or more transient segments;

encode the residual segment; and

transmit the one or more encoded transient segments and the encoded residual segment to an aggregator, which generates information related to the health of the subject based on the one or more encoded transient segments and the encoded residual segment.