Method and apparatus for error detection in digital communications

• US 6,170,073 B1
• Filed: 03/21/1997
• Issued: 01/02/2001
• Est. Priority Date: 03/29/1996
• Status: Expired due to Term

• Current Assignee: Intellectual Ventures I LLC (Intellectual Ventures LLC)
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Honkanen, Tero, Vainio, Janne, Jarvinen, Kari, Haavisto, Petri
• Primary Examiner(s): Moise, Emmanuel L.
• Assistant Examiner(s): LIN, SAMUEL K
• Application Number:
  US08/821,537
• Time in Patent Office: 1,383 Days
• Field of Search: 371/5.1, 371/5.2, 371/5.5, 371/6.3, 371/37.7, 371/41, 371/31, 371/37.02, 714/704, 714/705, 714/708, 714/709, 714/746, 714/758, 714/774, 714/747, 714/776, 370/333
• US Class Current: 714/758
• CPC Class Codes: H03M 13/47 Error detection, forward error correction or error protection, not provided for in groups H03M13/01 - H03M13/37
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 1/007 Unequal error protection for format H04L1/0078; for codes per se H03M13/35

Abstract

An encoder encodes digital signals representative of data by classifying the digital signals into first and second classes indicative of their influence on data quality and subjects them to error detection encoding capable of generating at least two error detection codes which respectively correspond to the first and second classes. A decoder receives the encoded digital signals classified into first and second digital signal classes, decodes the error detection codes, and generates error signals, corresponding to the respective digital signal classes, from which the quality of the received digital signals is estimated and the utility of the received digital signals is determined.

Claims

1. An encoder for digital communication, comprising:

means for encoding data into digital signals representative of said data,

means for classifying the digital signals into first and second classes indicative of their influence on data quality, and

means for error detection encoding capable of generating at least two error detection codes, wherein the at least two error detection codes respectively correspond to the first and second classes and wherein said first and second classes are overlapping.

2. An encoder according to claim 1, wherein the data is speech and the digital signals are classified according to their importance to speech quality.

3. An encoder according to claim 1 comprising a first coding means generating the first class and a second coding means for generating the second class and sequentially operable to the first coding means.

4. An encoder according to claim 3, wherein the first coding means is a speech encoder and the second coding means is a channel encoder.

5. An encoder according to claim 1 comprising means for receiving frame formatted digital signals.

6. A decoder for digital communication, including:

means for receiving encoded digital signals classified into first and second digital signal classes corresponding to the importance of said digital signals, wherein said first and second classes are overlapping;

error detection decoding means for generating error signals corresponding to the respective first and second digital signal classes, and

means for estimating received digital signal quality responsive to the error signals generated by the error detection decoding means.

7. A decoder according to claim 6, further comprising means for determining the utility of the received digital signals dependent on a result of the quality estimating means.

8. A decoder according to claim 6 wherein said first and second digital signal classes are associated with respective weighting parameters k1, k2 indicative of the importance of said first and second digital signal classes.

9. A decoder according to claim 8, wherein values of respective weighting parameters k₁,k₂ are variable in accordance with an error level for the received digital signals.

10. A decoder according to claim 8 wherein the quality estimating means is operable in accordance with the following relationship;

11. A decoder according to claim 10, wherein the digital signals are determined to be usable for B less than a predetermined threshold.

12. A decoder according to claim 6 wherein said digital signals are representative of speech and are classified in accordance with their importance to speech quality.

13. A decoder according to claim 12, wherein the digital signals are formatted into speech frames comprising speech parameters.

14. A decoder according to claim 12, further including a speech decoder for decoding the received digital signals into speech.

15. A decoder according to claim 10, wherein the digital signals are formatted into speech frames comprising speech parameters, and wherein a frame is determined good for B less than the predetermined threshold and bad for B greater than an equal to the predetermined threshold.

16. A decoder according to claim 15, further comprising a speech decoding means and wherein a previous good frame is substitutable for a bad frame, and the previous good frame is transferable to the speech decoding means.

17. A decoder according to claim 15, wherein digital signals in a frame are attenuable in accordance with the result of the quality estimating means associated with said frame.

18. Communication apparatus including;

an encoder for digital speech communication comprising,

means for encoding speech data into digital signals representative of said data,

means for classifying the digital signals into first and second digital signal classes indicative of their influence on data quality, and

means for error detection encoding adapted to generate at least two error detection codes that respectively correspond to the first and second digital signal classes, and wherein said first and second classes are overlapping, and

a decoder for digital speech communication, comprising,

means for receiving encoded digital signals from said encoder,

error detection decoding means for generating error signals from the at least two error detection codes corresponding to respective digital signal classes,

means for estimating the quality of the received digital signals responsive to the error signals generated by the error detection decoding means, and

means for determining the utility of the received digital signals dependent on a result of the quality estimating means.

19. Communication apparatus according to claim 18, comprising a first coding means generating the first class and a second coding means for generating the second class and sequentially operable to the first coding means.

20. Communication apparatus according to claim 18 comprising means for processing frame formatted digital signals.

21. Communication apparatus according to claim 18 including;

means for receiving encoded digital signals classified into first and second digital signal classes corresponding to importance of said digital signals, and

error detection decoding means for generating an error signal corresponding to respective first and second digital signal classes.

22. Communication apparatus according to claim 21, further comprising means for determining the utility of the received digital signals dependent on a result of the quality estimating means.

23. Communication apparatus according to claim 18 wherein said first and second digital signal classes are associated with respective weighting parameters k₁, k₂ indicative of the importance of said first and second digital signal classes.

24. Communication apparatus according to claim 23, wherein the values of respective weighting parameters k₁, k₂ are variable in accordance with an error level for the received digital signals.

25. Communication apparatus according to claim 23 wherein the quality estimating means is operable in accordance with the following relationship:

26. Communication apparatus according to claim 25, wherein the digital signals are determined to be usable for B less than a predetermined threshold.

27. Communication apparatus according to claim 18 wherein the digital signals are representative of speech and are classified in accordance with their importance to speech quality.

28. Communication apparatus according to claim 27, wherein the digital signals are formatted into speech frames comprising speech parameters.

29. Communication apparatus according to claim 27 wherein the decoder further comprises a speech decoder for decoding the received digital signals into speech.

30. Communication apparatus according to 25, wherein the digital signals are formatted into speech frames comprising speech parameters and wherein a frame is determined good for B less than predetermined threshold and bad for B greater than an equal to the predetermined threshold.

31. Communication apparatus according to claim 18, wherein the digital signals are formatted into speech frames comprising speech parameters and wherein the decoder is operable such that a previous good frame is substitutable for a bad frame, and the previous good frame is transferable to the speech decoding means.

32. Communication apparatus according to claim 18, wherein the digital signals are formatted into speech frames comprising speech parameters and wherein the decoder is operable to attenuate digital signals for a frame in accordance with the result of the quality estimating means associated with said frame.

33. Communication apparatus according to claim 18 wherein the apparatus further comprises a base-station or a mobile terminal in a digital radio telephone system.

34. A radio telephone network, comprising at least one base-station operable for a respective geographical area, and a plurality of mobile terminals operable for communication with the at least one base-station, wherein the at least one base-station and plurality of mobile terminals respectively include communication apparatus comprising:

an encoder for digital communication comprising,

means for encoding data into digital signals representative of said data,

means for classifying the digital signals into first and second digital signal classes indicative of their influence on data quality, and

means for error detection encoding adapted to generate at least two error detection codes that respectively correspond to the first and second digital signal classes, and wherein said first and second classes are overlapping, and

a decoder for digital communication, comprising,

means for receiving encoded digital signals from said encoder,

error detection decoding means for generating error signals from the at least two error detection codes corresponding to respective digital signal classes,

means for estimating the quality of the received digital signals responsive to the error signals generated by the error detection decoding means, and

means for determining the utility of the received digital signals dependent on a result of the quality estimating means.

35. A method for digital communication encoding, comprising encoding data into digital signals representative of said data, classifying the digital signals into first and second classes according to their influence on data quality wherein said first and second classes are overlapping, and generating at least two error detection codes respectively corresponding to the first and second classes.

36. A method according to claim 35, wherein the data is speech and the digital signals are classified according to their importance to speech quality.

37. A method according to claim 35 the first class is generated in a first coding means and the second class is generated in a second coding means sequentially operable to the first coding means.

38. A method according to claim 37, wherein the data is speech and wherein the first coding means is a speech encoder and the second coding means is a channel encoder.

39. A method according to claim 35 wherein said digital signals comprise frame formatted digital signals.

40. A method according to claim 39, wherein the digital signals are representative of speech and are classified in accordance with their importance to speech quality.

41. A method according to claim 40, wherein the digital signals are formatted into speech frames comprising speech parameters.

42. A method according to claim 40, further comprising decoding the received digital signals into speech.

43. A method for digital communication decoding, comprising the steps of:

receiving encoded digital signals classified into first and second digital signal classes corresponding to the importance of said digital signals wherein said first and second classes are overlapping,

decoding the received encoded digital signals for detecting errors corresponding respectively to said first and second digital signal classes, and

estimating the quality for received digital signals based on the result of the decoding of received encoded digital signals.

44. A method according to claim 43, further comprising determining the utility of the received digital signals based on a result of estimating the quality of the received digital signals.

45. A method according to claim 43 further comprising associating respective weighting parameters k₁, k₂ indicative of digital signal class importance with respective first and second digital signal classes.

46. A method according to claim 45, further comprising varying the value of the respective weighting parameters k₁, k₂ in accordance with an error level for the received digital signals.

47. A method according to claim 45 operable for estimating the quality of the received digital signals in accordance with the following relationship:

48. A method according to claim 47, further comprising determining digital signals usable for B<

1.0.

49. A method according to claim 48 wherein the digital signals are formatted into speech frames comprising speech parameters, and determining a frame good for B<

1.0.

50. A method according to claim 49, further comprising substituting a previous good frame for a bad frame and decoding the previous good frame into speech.

51. A method according to claim 49, further comprising attenuating digital signals in a frame in accordance with a result of estimating the quality of the received digital signals associated with said frame.