System for wireless transmission and receiving of information and method of operation thereof

• US 5,745,532 A
• Filed: 06/02/1995
• Issued: 04/28/1998
• Est. Priority Date: 03/12/1992
• Status: Expired due to Term

• Current Assignee: NTP Incorporated
• Original Assignee: NTP Incorporated
• Inventors: Campana, Thomas J. Jr.
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): GHAYOUR, MOHAMMAD H
• Application Number:
  US08/458,651
• Time in Patent Office: 1,061 Days
• Field of Search: 375/347, 455/52.1, 455/52.2, 455/52.3, 455/65, 455/101, 455/278.1, 455/296, 455/132, 455/272, 455/273
• US Class Current: 375/347
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04L 1/004 by using forward error control H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00
• CPC Class Codes: H04L 1/02 by diversity reception
• CPC Class Codes: H04L 27/22 Demodulator circuits; Receiver circuits
• CPC Class Codes: H04L 7/042 Detectors therefor, e.g. correlators, state machines digital correlators in general G06F17/15
• CPC Class Codes: H04W 28/06 Optimizing the usage of the radio link, e.g. header compression, information sizing , discarding information system modifying transmission characteristic according to link quality by modifying frame length H04L1/0007; dynamic adaptation of the packet size for flow control or congestion control H04L47/365
• CPC Class Codes: H04W 68/00 User notification, e.g. alerting and paging, for incoming communication, change of service or the like

Abstract

A system and method is disclosed for wireless transmission of information which is subject to fading by using a RF carrier modulated with a subcarrier modulated with the information. The system has a bus interface which communicates with a digital signal processor which controls the transmitting and receiving circuitry functions. The bus interface is for connection to a computer bus which is connected to a computer which originates information to be transmitted by transmitting circuitry and which receives information from receiving circuitry. The digital signal processor provides first and second encoded information streams each comprising the information to be transmitted with the second stream being delayed by a time delay interval with respect to the first stream which is equal to or greater than the fading interval. The first and second encoded information streams modulate cycles of the subcarrier to produce first and second parallel information streams which are time offset by the time delay interval. The receiving circuitry has a detector for detecting transmitted first and second parallel information streams with the second parallel information stream being delayed from the first parallel information stream by the time delay interval. The digital signal processor determines if faded information is present in the frames of the detected first and second parallel information streams by processing the error correction code therein to determine if a number of bit errors are present which exceed the bit error correction capacity of the error correction code. The digital signal processor places an error marker within the detected first and second parallel information streams to mark each faded information unit and controls replacement of each error marker within at least one of the first and second parallel information streams with replacement data bits within a frame in one of the first and second parallel information streams which were time offset at transmission by the time delay interval to produce error free transmitted information.

Claims

1. Receiving circuitry for reception of wireless transmission of information which is subject to fading for a time interval with a radio frequency carrier modulated with a subcarrier with the subcarrier modulated with first and second encoded information streams each containing the information to produce first and second parallel information streams modulating cycles of the subcarrier with the first parallel information stream containing the first encoded information stream and with the second parallel information stream containing the second encoded information stream with the first and second parallel information streams being transmitted with a time delay interval between the first and second parallel information streams which is equal to or greater than the time interval, the first and second encoded information streams comprise a plurality of synchronization bits for synchronizing the receiving circuitry with transmitting circuitry transmitting the radio frequency carrier modulated with the subcarrier and frames of information, a plurality of the frames each having a plurality of bits encoding error correction code and a plurality of bits encoding the information with the error correction code of the frames of the first encoded information stream not being capable of correcting for a fade of the time interval producing faded information in the first parallel information stream and representing a bit error if uncorrected which will cause a loss of synchronism between the receiving circuitry and the transmitting circuitry and the error correction code of the frames of the second encoded information stream not being capable of correcting for a fade of the time interval producing faded information in the second parallel information stream and representing a bit error if uncorrected which will cause a loss of synchronism between the receiving and the transmitting circuitry, the receiving circuitry comprising:

a detector for detecting the transmitted first and second parallel information streams; and

a processor, coupled to the detector and responsive to the detected parallel information streams including the plurality of synchronization bits with the synchronization bits synchronizing the receiving circuitry with the transmitting circuitry, for determining if faded information is present in at least one of the detected first and second parallel information streams, in response to determined faded information replacing the faded information caused by a fade with replacement information from at least one of the first and second parallel information streams which is time offset at transmission from the faded information by the time delay interval to maintain synchronization between the receiving and transmitting circuitry and outputting transmitted information including the replacement information.

2. Receiving circuitry in accordance with claim 1 wherein:

the processor comprises a digital signal processor for processing detected individual cycles of the subcarrier to calculate an integral of at least one selected modulated part of each of the individual cycles, numerically comparing each of the calculated integrals with a plurality of stored numerical ranges which ranges each represent one of a plurality of possible numerical values that the selected part may encode to identify a stored range numerically including the calculated integral and substituting for the at least one selected part of each of the cycles the one of the plurality of numerical values representative of the identified stored range including the calculated integral with each numerical value encoding at least a part of an information unit in one of the first and second parallel information streams; and

wherein

the digital signal processor processes the first and second parallel information streams containing the substituted numerical values for determining if the faded information is present.

3. Receiving circuitry in accordance with claim 2 wherein:

the digital signal processor calculates the integral by taking a plurality of samples of each selected modulated part of each of the individual cycles with each sample having a numerical value and each sample is compared with a range of numerical values representing a valid sample which should be included within the calculation of the integral and when the comparison reveals that the sample value is outside the range of numerical values, the compared sample value is replaced with a value which is a function of the sample values adjacent the sample value which is replaced.

4. Receiving circuitry in accordance with claim 3 wherein:

the compared sample value is replaced with a value which is an average of at least one sample value which precedes the compared sample value and at least one sample value which succeeds the compared sample value.

5. Receiving circuitry in accordance with claim 1 wherein:

the processor places an error marker within the detected first and second parallel information streams to mark each faded information unit within the faded information requiring replacement and controls replacement of each error marker within at least one of the first and second parallel information streams with replacement bits within one of the first and second parallel information streams which were time offset at transmission by the time delay interval to produce error free transmitted information.

6. Receiving circuitry in accordance with claim 2 wherein:

the processor places an error marker within the detected first and second parallel information streams to mark each faded information unit within the faded information requiring replacement and controls replacement of each error marker within at least one of the first and second parallel information streams with replacement bits within one of the first and second parallel information streams which were time offset at transmission by the time delay interval to produce error free transmitted information.

7. Receiving circuitry in accordance with claim 3 wherein:

the processor places an error marker within the detected first and second parallel information streams to mark each faded information unit within the faded information requiring replacement and controls replacement of each error marker within at least one of the first and second parallel information streams with replacement bits within one of the first and second parallel information streams which were time offset at transmission by the time delay interval to produce error free transmitted information.

8. Receiving circuitry in accordance with claim 4 wherein:

the processor places an error marker within the detected first and second parallel information streams to mark each faded information unit within the faded information requiring replacement and controls replacement of each error marker within at least one of the first and second parallel information streams with replacement bits within one of the first and second parallel information streams which were time offset at transmission by the time delay interval to produce error free transmitted information.

9. Receiving circuitry in accordance with claim 1 wherein:

bits of each of the first and second parallel information streams modulate cycles of the subcarrier with each cycle of the subcarrier being modulated by bits at a plurality of separated angular positions.

10. Receiving circuitry in accordance with claim 1 wherein:

groups of bits of the first and second parallel information streams each modulate a width of parts of the subcarrier with pulse width modulation.

11. Receiving circuitry in accordance with claim 2 wherein:

bits of each of the first and second parallel information streams modulate cycles of the subcarrier with each cycle of the subcarrier being modulated by bits at a plurality of separated angular positions.

12. Receiving circuitry in accordance with claim 2 wherein:

groups of bits of the first and second parallel information streams each modulate a width of parts of the subcarrier with pulse width modulation.

13. Receiving circuitry in accordance with claim 3 wherein:

bits of each of the first and second parallel information streams modulate cycles of the subcarrier with each cycle of the subcarrier being modulated by bits at a plurality of separated angular positions.

14. Receiving circuitry in accordance with claim 3 wherein:

groups of bits of the first and second parallel information streams each modulate a width of parts of the subcarrier with pulse width modulation.

15. Receiving circuitry in accordance with claim 4 wherein:

bits of each of the first and second parallel information streams modulate cycles of the subcarrier with each cycle of the subcarrier being modulated by bits at a plurality of separated angular positions.

16. Receiving circuitry in accordance with claim 4 wherein:

groups of bits of the first and second parallel information streams each modulate a width of parts of the subcarrier with pulse width modulation.

17. Receiving circuitry in accordance with claim 5 wherein:

bits of each of the first and second parallel information streams modulate cycles of the subcarrier with each cycle of the subcarrier being modulated by bits at a plurality of separated angular positions.

18. Receiving circuitry in accordance with claim 5 wherein:

groups of bits of the first and second parallel information streams each modulate a width of parts of the subcarrier with pulse width modulation.

19. Receiving circuitry in accordance with claim 6 wherein:

bits of each of the first and second parallel information streams modulate cycles of the subcarrier with each cycle of the subcarrier being modulated by bits at a plurality of separated angular positions.

20. Receiving circuitry in accordance with claim 6 wherein:

groups of bits of the first and second parallel information streams each modulate a width of parts of the subcarrier with pulse width modulation.

21. Receiving circuitry in accordance with claim 7 wherein:

bits of each of the first and second parallel information streams modulate cycles of the subcarrier with each cycle of the subcarrier being modulated by bits at a plurality of separated angular positions.

22. Receiving circuitry in accordance with claim 7 wherein:

groups of bits of the first and second parallel information streams each modulate a width of parts of the subcarrier with pulse width modulation.

23. Receiving circuitry in accordance with claim 8 wherein:

bits of each of the first and second parallel information streams modulate cycles of the subcarrier with each cycle of the subcarrier being modulated by bits at a plurality of separated angular positions.

24. Receiving circuitry in accordance with claim 8 wherein:

groups of bits of the first and second parallel information streams each modulate a width of parts of the subcarrier with pulse width modulation.

25. Receiving circuitry in accordance with claim 1 further comprising:

a computer having an information transmission medium; and

a bus interface, connected to the information transmission medium and coupled to the processor, for receiving outputted transmitted information and in response to connection to the information transmission medium transmitting the outputted transmitted information to the information transmission medium for transmission to the computer.

26. Receiving circuitry in accordance with claim 2 further comprising:

a computer having an information transmission medium; and

a bus interface, connected to the information transmission medium and coupled to the processor, for receiving outputted transmitted information and in response to connection to the information transmission medium transmitting the outputted transmitted information to the information transmission medium for transmission to the computer.

27. Receiving circuitry in accordance with claim 3 further comprising:

a computer having an information transmission medium; and

a bus interface, connected to the information transmission medium and coupled to the processor, for receiving outputted transmitted information and in response to connection to the information transmission medium transmitting the outputted transmitted information to the information transmission medium for transmission to the computer.

28. Receiving circuitry in accordance with claim 4 further comprising:

a computer having an information transmission medium; and

a bus interface, connected to the information transmission medium and coupled to the processor, for receiving outputted transmitted information and in response to connection to the information transmission medium transmitting the outputted transmitted information to the information transmission medium for transmission to the computer.

29. Receiving circuitry in accordance with claim 5 further comprising:

a computer having an information transmission medium; and

a bus interface, connected to the information transmission medium and coupled to the processor, for receiving outputted error free transmitted information and in response to connection to the information transmission medium transmitting the outputted error free transmitted information to the information transmission medium for transmission to the computer.

30. Receiving circuitry in accordance with claim 9 further comprising:

a computer having an information transmission medium; and

a bus interface, connected to the information transmission medium and coupled to the processor, for receiving outputted transmitted information and in response to connection to the information transmission medium transmitting the outputted transmitted information to the information transmission medium for transmission to the computer.

31. Receiving circuitry in accordance with claim 10 further comprising:

a computer having an information transmission medium; and

a bus interface, connected to the information transmission medium and coupled to the processor, for receiving outputted transmitted information and in response to connection to the information transmission medium transmitting the outputted transmitted information to the information transmission medium for transmission to the computer.

32. A method for reception of wireless transmission of information which is subject to fading for a time interval with a radio frequency carrier modulated with a subcarrier with the subcarrier modulated with first and second encoded information streams each containing the information to produce first and second parallel information streams modulating cycles of the subcarrier with the first parallel information stream containing the first encoded information stream and with the second parallel information stream containing the second encoded information stream with the first and second parallel information streams being transmitted with a time delay interval between the first and second parallel information streams which is equal to or greater than the time interval, the first and second encoded information streams comprise a plurality of synchronization bits for synchronizing the wireless transmission of the information with the reception of the information, a plurality of the frames each having a plurality of bits encoding error correction code and a plurality of bits encoding the information with the error correction code of the frames of the first encoded information stream not being capable of correcting for a fade of the time interval producing faded information in the first parallel information stream and representing a bit error if uncorrected which will cause a loss of synchronism between the transmission and the reception of the information and the error correction code of the frames of the second encoded information stream not being capable of correcting for a fade of the time interval producing faded information in the second parallel information stream and representing a bit error if uncorrected which will cause a loss of synchronism between the transmission and the reception of the information comprising the steps:

detecting the transmitted first and second parallel information streams; and

synchronizing the reception of the information with the transmission of the information with the synchronization bits of the detected first and second parallel information streams, determining if faded information is present in at least one of the detected first and second parallel information streams, in response to determined faded information replacing the faded information caused by a fade with replacement information from at least one of the first and second parallel information streams which is time offset at transmission from the faded information by the time delay interval to maintain synchronization between the reception and the transmission of the information and outputting transmitted information including the replacement information.

33. A method in accordance with claim 32 further comprising:

processing detected individual cycles of the subcarrier to calculate an integral of at least one selected modulated part of each of the individual cycles, numerically comparing each of the calculated integrals with a plurality of stored numerical ranges which ranges each represent one of a plurality of possible numerical values that the selected part may encode to identify a stored range numerically including the calculated integral and substituting for the at least one selected part of each of the cycles the one of the plurality of numerical values representative of the identified stored range including the calculated integral with each numerical value encoding at least a part of an information unit in one of the first and second parallel information streams; and

processing the first and second parallel information streams containing the substituted numerical values for determining if the faded information is present.

34. A method in accordance with claim 33 wherein:

the integral is calculated by taking a plurality of samples of each selected modulated part of each of the individual cycles with each sample having a numerical value and each sample is compared with a range of numerical values representing a valid sample which should be included within the calculation of the integral and when the comparison reveals that the sample value is outside the range of numerical values, the compared sample value is replaced with a value which is a function of the sample values adjacent the sample value which is replaced.

35. A method in accordance with claim 34 wherein:

the compared sample value is replaced with a value which is an average of at least one sample value which precedes the compared sample value and at least one sample value which succeeds the compared sample value.

36. A method in accordance with claim 32 further comprising:

placing an error marker within the detected first and second parallel information streams to mark each faded information unit within the faded information requiring replacement and replacing each error marker within at least one of the first and second parallel information streams with replacement bits within one of the first and second parallel information streams which were time offset at transmission by the time delay interval to produce error free transmitted information.

37. A method in accordance with claim 33 further comprising:

placing an error marker within the detected first and second parallel information streams to mark each faded information unit within the faded information requiring replacement and replacing each error marker within at least one of the first and second parallel information streams with replacement bits within one of the first and second parallel information streams which were time offset at transmission by the time delay interval to produce error free transmitted information.

38. A method in accordance with claim 34 further comprising:

placing an error marker within the detected first and second parallel information streams to mark each faded information unit within the faded information requiring replacement and replacing each error marker within at least one of the first and second parallel information streams with replacement bits within one of the first and second parallel information streams which were time offset at transmission by the time delay interval to produce error free transmitted information.

39. A method in accordance with claim 35 further comprising:

placing an error marker within the detected first and second parallel information streams to mark each faded information unit within the faded information requiring replacement and replacing each error marker within at least one of the first and second parallel information streams with replacement bits within one of the first and second parallel information streams which were time offset at transmission by the time delay interval to produce error free transmitted information.

40. A method in accordance with claim 32 wherein:

bits of each of the first and second parallel information streams modulate cycles of the subcarrier with each cycle of the subcarrier being modulated by bits at a plurality of separated angular positions.

41. A method in accordance with claim 32 wherein:

groups of bits of the first and second parallel information streams each modulate a width of parts of the subcarrier with pulse width modulation.

42. A method in accordance with claim 33 wherein:

bits of each of the first and second parallel information streams modulate cycles of the subcarrier with each cycle of the subcarrier being modulated by bits at a plurality of separated angular positions.

43. A method in accordance with claim 33 wherein:

groups of bits of the first and second parallel information streams each modulate a width of parts of the subcarrier with pulse width modulation.

44. A method in accordance with claim 34 wherein:

bits of each of the first and second parallel information streams modulate cycles of the subcarrier with each cycle of the subcarrier being modulated by bits at a plurality of separated angular positions.

45. A method in accordance with claim 34 wherein:

groups of bits of the first and second parallel information streams each modulate a width of parts of the subcarrier with pulse width modulation.

46. A method in accordance with claim 35 wherein:

bits of each of the first and second parallel information streams modulate cycles of the subcarrier with each cycle of the subcarrier being modulated by bits at a plurality of separated angular positions.

47. A method in accordance with claim 35 wherein:

groups of bits of the first and second parallel information streams each modulate a width of parts of the subcarrier with pulse width modulation.

48. A method in accordance with claim 36 wherein:

bits of each of the first and second parallel information streams modulate cycles of the subcarrier with each cycle of the subcarrier being modulated by bits at a plurality of separated angular positions.

49. A method in accordance with claim 36 wherein:

groups of bits of the first and second parallel information streams each modulate a width of parts of the subcarrier with pulse width modulation.

50. A method in accordance with claim 37 wherein:

bits of each of the first and second parallel information streams modulate cycles of the subcarrier with each cycle of the subcarrier being modulated by bits at a plurality of separated angular positions.

51. A method in accordance with claim 37 wherein:

groups of bits of the first and second parallel information streams each modulate a width of parts of the subcarrier with pulse width modulation.

52. A method in accordance with claim 38 wherein:

bits of each of the first and second parallel information streams modulate cycles of the subcarrier with each cycle of the subcarrier being modulated by bits at a plurality of separated angular positions.

53. A method in accordance with claim 38 wherein:

groups of bits of the first and second parallel information streams each modulate a width of parts of the subcarrier with pulse width modulation.

54. A method in accordance with claim 39 wherein:

bits of each of the first and second parallel information streams modulate cycles of the subcarrier with each cycle of the subcarrier being modulated by bits at a plurality of separated angular positions.

55. A method in accordance with claim 39 wherein:

groups of bits of the first and second parallel information streams each modulate a width of parts of the subcarrier with pulse width modulation.

56. A method in accordance with claim 32 wherein:

the information is outputted by receiving circuitry and in response to connection of an interface of the receiving circuitry to an information transmission medium transmitting the outputted transmitted information to a computer including the information transmission medium.

57. A method in accordance with claim 33 wherein:

the information is outputted by receiving circuitry and in response to connection of an interface of the receiving circuitry to an information transmission medium transmitting the outputted transmitted information to a computer including the information transmission medium.

58. A method in accordance with claim 34 wherein:

the information is outputted by receiving circuitry and in response to connection of an interface of the receiving circuitry to an information transmission medium transmitting the outputted transmitted information to a computer including the information transmission medium.

59. A method in accordance with claim 35 wherein:

the information is outputted by receiving circuitry and in response to connection of an interface of the receiving circuitry to an information transmission medium transmitting the outputted transmitted information to a computer including the information transmission medium.

60. A method in accordance with claim 36 wherein:

the error free information is outputted by receiving circuitry and in response to connection of an interface of the receiving circuitry to an information transmission medium transmitting the outputted error free transmitted information to a computer including the information transmission medium.

61. A method in accordance with claim 40 wherein:

the information is outputted by receiving circuitry and in response to connection of an interface of the receiving circuitry to an information transmission medium transmitting the outputted transmitted information to a computer including the information transmission medium.

62. A method in accordance with claim 41 wherein:

the information is outputted by receiving circuitry and in response to connection of an interface of the receiving circuitry to an information transmission medium transmitting the outputted transmitted information to a computer including the information transmission medium.