System and method for transmitting aural information between a computer and telephone equipment

• US 5,940,479 A
• Filed: 10/01/1996
• Issued: 08/17/1999
• Est. Priority Date: 10/01/1996
• Status: Expired due to Term

• Current Assignee: RPX Clearinghouse LLC (RPX Corporation)
• Original Assignee: Northern Telecom Limited (Nortel Networks Corporation)
• Inventors: Johnson, Michael W., Jasuja, Ishwar V., Jain, Jaswant R., Guy, Kenneth R., Roth, Jacques A., Misunas, David, Lee, Anthony Y., Lam, Simon S., Juandy, Albert
• Primary Examiner(s): Kuntz, Curtis A.
• Assistant Examiner(s): Eng, George
• Application Number:
  US08/724,655
• Time in Patent Office: 1,050 Days
• Field of Search: 379/90.01, 379/93.01, 379/93.05-93.09, 379/93.11, 379/93.14-93.15, 379/93.28-93.29, 379/93.31, 379/93.33, 379/93.37, 370/254-256, 370/352, 370/389, 370/392, 370/395, 370/400-408, 370/465-467, 370/410, 370/522, 370/527-529, 371/35, 371/37.01-37.02, 371/48, 371/49.1, 395/185.02, 395/185.05, 395/185.09, 364/265.1-265.3, 364/266.3, 364/944.5, 364/945.6
• US Class Current: 379/93.01
• CPC Class Codes: H03M 13/00 Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes error detection or error correction for analogue/digital, digital/analogue or code conversion H03M1/00 – H03M11/00; specially adapted for digital computers G06F11/08; for information storage based on relative movement between record carrier and transducer G11B, e.g. G11B20/18; for static stores G11C
• CPC Class Codes: H04L 65/103 in the network
• CPC Class Codes: H04L 65/104 in the network
• CPC Class Codes: H04L 65/1069 Session establishment or de-establishment
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/765 intermediate
• CPC Class Codes: H04M 7/1205 where the types of switching equipement comprises PSTN/ISDN equipment and switching equipment of networks other than PSTN/ISDN, e.g. Internet Protocol networks

Abstract

A system and method for transmitting aural signals across a wide area network (WAN) from a local phone coupled to a computer, e.g., a PC-phone, to a remote phone coupled to a KTS, PBX, or PSTN, for example. This capability is provided by the gateway unit of the present invention. The system of the present invention is quickly installed in a server or a personal computer coupled to a local area network. The system is connected to one or more of a PSTN, a private branch exchange, a key telephone system, a telephone, a facsimile machine, and a modem. In the case of voice transmission, a gateway unit translates received telephony signal into a format that is compatible with the telephone system or equipment connected thereto. The present invention can provide a voice quality that approaches, equals, or exceeds the voice quality of conventional telephone switched networks. This high voice quality is achieved by utilizing a high quality voice digitization algorithm on both the PC-phone and the gateway, by ensuring a low maximum network delay between the PC-phone and the gateway, by permitting a dynamic compensation for variations in network delay, and by utilizing a forward error correction technique for transmission over WANs that can recreate lost or delayed signals in a manner that recreates the signal so the lost signal is typically not detectable by a user.

Claims

1. A method for transmitting aural signals across a wide area digital data network and a target phone system, comprising the steps of:

receiving a first aural signal having a first configuration, said first aural signal representing a voice signal;

converting said first aural signal into a first data signal having a first network configuration that can be transmitted through a first local area network including the steps of;

converting said first aural signal to a digital signal;

generating first and second data transmission unit signals, having said first network configuration, from said digital signal, said first data transmission unit signal includes;

a first voice unit signal; and

a correction unit signal including a representation of a second voice unit signal from a second data transmission unit signal, transmitted separately from a first data transmission unit signal, said correction unit signal for recreating said second data transmission unit signal if not received by said destination converter;

wherein said first data signal represents said first data transmission unit signal;

transmitting said first data signal to a first communication device through said first local area network;

transmitting said first data signal from said first communication device to a second communication device in a second local area network through the wide area digital data network;

transmitting said first data signal to a destination converter through said second local area network;

converting said first data signal to a second data signal that is compatible with the target phone system; and

transmitting said second data signal from said destination converter to a first receiver via the target phone system;

wherein said steps of receiving a first aural signal and converting said first aural signal are performed by a PC-phone.

2. The method of claim 1, wherein said first data signal represents one of a first signal and a call control signal, said first signal in the form of one of a digitized voice signal, a demodulated modem signal, and a demodulated facsimile signal.

3. The method of claim 2, wherein said call control signal represents one of call setup information, call teardown information, call priority information, and call status information.

4. The method of claim 1, further comprising the step of converting said second data signal to a second aural signal wherein said second aural signal is one of a near toll quality representation of said first aural signal and a toll-quality representation of said first aural signal.

5. The method of claim 1, wherein said step of converting said first aural signal to a digital signal includes the steps of

converting said first aural signal to a first converted digital signal using a pulse code modulation algorithm;

and

compressing said first converted signal using a compression algorithm to generate said digital signal.

6. The method of claim 5, wherein said compression algorithm is an ITU standard compression algorithm of Jun. 21, 1995.

7. The method of claim 1, further comprising the step of:

identifying said correction unit signal in said first data transmission unit signal after receiving said first data signal; and

utilizing said correction unit signal to generate a recreated second voice unit signal of said second data transmission unit signal, wherein said recreated second voice unit signal is of a lower quality than said second data transmission unit signal when said correction unit signal includes less data than a voice unit signal of said second data transmission unit signal.

8. The method of claim 1, wherein said first data transmission unit signal represents a voice signal having a first duration.

9. The method of claim 8, further comprising the step of:

dynamically reducing the time required for transmitting data through said wide area digital data network by reducing the amount of information in said first data transmission unit signal without reducing said first duration.

10. The method of claim 1, further comprising the steps of:

measuring a first delay representing the time period between transmitting said first data signal to said first communication device and receiving said first data signal at said destination converter;

dynamically adjusting a buffer based upon the variation in said first delay and an expected delay of the network.

11. The method of claim 1, further comprising the step of:

establishing priority for said first data signal across one of said wide area digital data network and leased lines.

12. The method of claim 1, wherein said first communication device is one of a network router and a network switch.

13. The method of claim 1, further comprising the step of:

establishing priority for said first data signal across said wide area digital data network using a priority protocol.

14. The method of claim 13, wherein said priority protocol is the resource reservation protocol.

15. A system for transmitting aural signals across a local area network, a wide area digital data network, and a target phone system, comprising:

a PC phone including

a first aural receiver for receiving a first aural signal having a first configuration, said first aural signal representing a voice signal; and

a first converter, disposed to receive signals from said first aural receiver, for converting said first aural signal into a first data signal having a first network configuration that can be transmitted through a first local area network including;

a second converter for converting said first aural signal to a digital signal; and

a transmission unit generator, disposed to receive said digital signal, for generating first and second data transmission unit signals, having said first network configuration, from said digital signal, said first data transmission unit signal including a first voice unit signal and a first correction unit signal including a representation of a second voice unit signal from a second data transmission unit signal, transmitted separately from said first data transmission unit signal, said correction unit signal for recreating said second voice unit signal if not received by said destination converter, wherein first data signal represents a first data transmission unit signal;

a first local network transmitter, disposed to receive signals from said first converter, for transmitting said first data signal onto said first local area network;

first and second communication devices, said first communication device disposed to receive signals from said first local network transmitter, for transmitting said first data signal to said second communication device in a second local area network through the wide area digital data network, said second communication device for transmitting said first data signal through said second local area network; and

said destination converter, disposed to receive signals from said second communication device, for converting said first data signal to a second data signal that is compatible with the target phone system and for transmitting said second data signal through the target phone system to a first receiver.

16. The system of claim 15, wherein said first data signal represents one of a first signal and a call control signal, said first signal is in the form of one of a digitized voice signal, a demodulated modem signal, and a demodulated facsimile signal.

17. The system of claim 16, wherein said call control signal represents one of call setup information, call teardown information, call priority information, and call status information.

18. The system of claim 15, further comprising a:

a second converter, disposed to receive signals from said destination converter, for converting said second data signal to a second aural signal wherein said second data signal is one of a near toll quality representation of said first aural signal and a toll-quality representation of said first aural signal.

19. The system of claim 15, wherein said second converter converts said first aural signal to a first converted digital signal using a pulse code modulation algorithm and compresses said first converted signal using a compression algorithm to generate said digital signal.

20. The system of claim 19, wherein said compression algorithm is an ITU standard compression algorithm.

21. The system of claim 15, wherein said destination converter includes a correction unit, for identifying said correction unit signal in said first data transmission unit signal after receiving said first data signal and for utilizing said correction unit signal to generate a recreated second voice unit signal of the data transmission unit signal, wherein said recreated second voice unit signal is of a lower quality than said second data transmission unit signal when said correction unit signal includes less data than a voice unit signal of said second data transmission unit signal.

22. The system of claim 15, wherein said first data transmission unit signal represents a voice signal having a first duration.

23. The system of claim 15, further comprising a priority management unit, disposed to receive signals from said first converter, for establishing priority for said first data signal across one of said wide area digital data network and leased lines.

24. The system of claim 15, wherein said first communication device is one of a network router and a network switch.

25. The system of claim 15, further comprising a priority management unit, disposed to receive signals from said first converter, for establishing priority for said first data signal across one of said wide area digital data network and leased lines using a priority protocol.

26. The system of claim 25, wherein said priority protocol is the resource reservation protocol.

27. A system for communications, comprising:

a conversion unit, disposed to receive an aural signal, including;

a converter for converting said aural signal to a digital signal; and

a transmission unit generator, disposed to receive said digital signal, for generating a plurality of data transmission unit signals from said digital signal, each of said data transmission unit signals capable of being transmitted via a network and including an aural unit signal and a correction unit signal, said correction unit signal including a representation of the aural unit signal from another of said data transmission unit signals, said correction unit signal for recreating the aural unit signal of said another data transmission unit signal, if not received by a destination converter.

28. The system of claim 27, wherein said aural signal is received from a PC-phone.

29. The system of claim 28, further comprising:

a correction unit, disposed to receive said data transmission unit signals, to identify when a first of said data transmission unit signals has not been received and to identify the correction unit signal in a second of said data transmission unit signals representing the aural unit signal in said first data transmission unit signal, to generate a recreated aural unit signal of said first data transmission unit signal, wherein said recreated second aural unit signal includes less data than the aural unit signal of said first data transmission unit signal.

30. The system of claim 27, further comprising:

a correction unit, disposed to receive said data transmission unit signals, to identify when a first of said data transmission unit signals has not been received and to identify the correction unit signal in a second of said data transmission unit signals representing the aural unit signal in said first data transmission unit signal, to generate a recreated aural unit signal of said first data transmission unit signal, wherein said recreated second aural unit signal includes less data than the aural unit signal of said first data transmission unit signal.

31. The system of claim 30, wherein said system transmits a plurality of data transmission unit signals having one of a near toll-quality and toll-quality.

32. The system of claim 30, further comprising:

a jitter buffer for storing received data transmission unit signals.

33. The system of claim 32, wherein a length of said jitter buffer is variable.

34. The system of claim 33, wherein said length of said jitter buffer is dependent upon a data delay variation.

35. The system of claim 34, wherein said jitter buffer is dynamically adjusted based upon said data delay variation.

36. The system of claim 30, further comprising:

a first network transmitter, disposed to receive signals from said conversion unit, for transmitting said data transmission unit signals to said network.

37. The system of claim 30, wherein said data transmission unit signals are in the form of packet data.

38. The system of claim 30, wherein said conversion unit receives data transmission unit signals and converts said data transmission unit signals into another aural signal.

39. The system of claim 27 wherein said aural signal includes a voice signal.

40. The system of claim 27, wherein said correction unit signal includes less data than the aural unit signal of said another data transmission unit signal.

41. A communications method, comprising the steps of:

receiving an aural signal;

converting said aural signal into a digital signal; and

generating a plurality of data transmission unit signals from said digital signal, each of said data transmission unit signals capable of being transmitted via a network and including an aural unit signal and a correction unit signal, said correction unit signal including a representation of said aural unit signal from another of said transmission unit signals, said correction unit signal for recreating said aural unit signal of said another data transmission unit signal, if not received by a destination converter.

42. The method of claim 41, wherein said aural signal is received from a PC-phone.

43. The method of claim 42, further comprising the steps of:

receiving data transmission unit signals;

identifying that a first of said data transmission unit signals has not been received;

identifying a correction unit representing the aural unit signal in said first data transmission unit signal; and

generating a recreated aural unit signal, representing said aural unit signal in said first data transmission unit signal using said identified correction unit,

wherein said recreated aural unit signal includes less data than said aural unit signal of said first data transmission unit signal.

44. The method of claim 41, further comprising the steps of:

receiving data transmission unit signals;

identifying that a first of said data transmission unit signals has not been received;

identifying a correction unit representing the aural unit signal in said first data transmission unit signal; and

generating a recreated aural unit signal, representing said aural unit signal in said first data transmission unit signal using said identified correction unit,

wherein said recreated aural unit signal includes less data than said aural unit signal of said first data transmission unit signal.

45. The method of claim 44, further comprising the step of transmitting a plurality of data transmission unit signals having one of a near toll-quality and toll-quality.

46. The method of claim 44, further comprising the step of:

using a jitter buffer to store received data transmission unit signals.

47. The method of claim 46, wherein a length of said jitter buffer is variable.

48. The method of claim 47, further comprising the step of:

varying said length of said jitter buffer based upon a data delay variation.

49. The method of claim 48, wherein said varying step includes the step of:

dynamically adjusting said length of said jitter buffer based upon said data delay variation.

50. The method of claim 44, further comprising the step of:

transmitting said data transmission unit signals onto said data network.

51. The method of claim 41 wherein said aural signal includes a voice signal.

52. The method of claim 41, wherein said correction unit signal includes less data than the aural unit signal of said another data transmission unit signal.