Mobile internet protocol voice system

• US 6,571,212 B1
• Filed: 08/15/2000
• Issued: 05/27/2003
• Est. Priority Date: 08/15/2000
• Status: Expired due to Term

• Current Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Dent, Paul W.
• Primary Examiner(s): MCFADDEN, SUSAN IRIS
• Application Number:
  US09/639,191
• Time in Patent Office: 1,015 Days
• Field of Search: 704/270, 704/270.1, 704/500, 379/88.17, 455/437, 455/439, 370/489
• US Class Current: 704/270.1
• 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 1/0065 Serial concatenated codes
• CPC Class Codes: H04L 63/0435 wherein the sending and receiving network entities apply symmetric encryption, i.e. same key used for encryption and decryption cryptographic mechanisms or cryptographic arrangements for symmetric key encryption H04L9/06
• CPC Class Codes: H04L 63/0457 wherein the sending and receiving network entities apply dynamic encryption, e.g. stream encryption cryptographic mechanisms or cryptographic arrangements for stream encryption H04L9/065
• CPC Class Codes: H04M 1/2535 adapted for voice communication over an Internet Protocol [IP] network Voice over Internet Protocol (VoIP) network equipment and services H04M7/006; implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP] H04L69/16
• CPC Class Codes: H04M 1/724 User interfaces specially adapted for cordless or mobile telephones
• CPC Class Codes: H04M 1/725 Cordless telephones user interfaces specially adapted therefor H04M1/724
• CPC Class Codes: H04M 2207/18 wireless networks
• CPC Class Codes: H04M 2242/04 for emergency applications
• CPC Class Codes: H04M 7/006 Networks other than PSTN/ISDN providing telephone service, e.g. Voice over Internet Protocol (VoIP) , including next generation networks with a packet-switched transport layer H04L65/00 takes precedence; aspects not specific to the type of network H04M3/00; special services in those networks H04M3/42
• CPC Class Codes: H04W 12/033 of the user plane, e.g. user's traffic
• CPC Class Codes: H04W 4/18 Information format or content conversion, e.g. adaptation by the network of the transmitted or received information for the purpose of wireless delivery to users or terminals

Abstract

A system for Internet Protocol voice communication comprises using both the Internet and wireless communications systems to communicate between two individuals. The speech is encrypted and encoded prior to transmission with an error indication field appended to the speech bits. Formatting for the Internet leg of the communications occurs according to Internet Protocol. Errors arising during the wireless transmission are addressed by appropriately ordering the encryption, error correction coding, and error detection together with the appended error indication field.

Claims

1. A method for transmitting telephone messages over the Internet between a first subscriber using a mobile terminal and a second subscriber, comprising:

digitizing speech in a first vocoder to be transmitted from said first subscriber to said second subscriber;

coding and formatting said digitized speech for wireless transmission to obtain coded and formatted digitized speech;

receiving said coded and formatted digitized speech at a wireless receiver;

decoding said coded and formatted digitized speech to obtain decoded speech and an error indication;

combining said error indication with said decoded speech and reformatting the decoded speech plus error indication for transmission over the Internet to a second vocoder;

deformatting said decoded speech plus error indication and applying the deformatted speech and error indication to the second vocoder to convert the decoded speech to an analog voice signal for said second subscriber, wherein said second vocoder uses said error indication to mask errors arising during said wireless transmission.

2. The method of claim 1 wherein coding said digitized speech comprises encryption using a secret key followed by error detection coding.

3. The method of claim 2 wherein coding said digitized speech further comprises error correction coding.

4. The method of claim 1 wherein decoding said coded and formatted digitized speech comprises error detection decoding.

5. The method of claim 4 wherein decoding said coded and formatted digitized speech comprises error correction decoding prior to said error detection decoding.

6. The method of claim 1 further comprising appending to said digitized speech at least one unused bit to each of a predetermined number of digital speech bits with said first vocoder.

7. The method of claim 6 wherein combining of said error indication with said decoded speech comprises combining said error indication with said at least one unused bit.

8. The method of claim 1 wherein combining said error indication with said decoded speech leaves unchanged a total number of bits associated with said decoded speech.

9. The method of claim 1 wherein formatting and deformatting preserves an identical number of bits from an input of said formatting to an output of said deformatting.

10. The method of claim 9 further comprising verifying that a number of deformatted bits agrees with a number of formatted bits with a bit counter.

11. The method of claim 9 further comprising verifying that a number of deformatted bytes agrees with a number of formatted bytes with a byte counter.

12. The method of claim 1 further comprising locating said second vocoder at an Internet telephony terminal used by said second subscriber.

13. The method of claim 12 further comprising implementing said second vocoder by software running on a personal computer.

14. The method of claim 1 wherein deformatting comprises deciphering the decoded speech plus error indication prior to inputting said speech and error indication to said second vocoder.

15. The method of claim 1 further comprising locating said second vocoder in an Internet telephony gateway associated with an Internet telephony service provider with whom said second subscriber has a subscription.

16. The method of claim 1 further comprising locating said second vocoder in an Internet telephony gateway associated with an Internet telephony service provider accessed via a dial-up line by said second subscriber.

17. The method of claim 1 wherein said second subscriber is also a wireless subscriber.

18. The method of claim 1 further comprising appending a blank field to said digitized speech, said blank field for holding the error indication.

19. The method of claim 18 further comprising encrypting said digitized speech and separately encrypting said blank field.

20. The method of claim 1 further comprising block enciphering a first class of speech bits separately from a second class of speech bits.

21. The method of claim 20 wherein coding and formatting said digitized speech comprises error correction coding said first class of speech bits.

22. The method of claim 21 wherein said error correction coding occurs subsequent to said enciphering.

23. The method of claim 20 wherein enciphering a second class of speech bits comprises bitwise enciphering a second class of speech bits.

24. A method for transmitting telephone messages over the Internet between a first subscriber using a mobile terminal and a second subscriber, comprising:

digitizing speech to be transmitted from said second subscriber to said first subscriber using a first vocoder adapted to a data rate used over a wireless path and formatting said digitized speech for transmission via the Internet;

receiving said speech via the Internet at a wireless network station and coding and reformatting said digitized speech for wireless transmission over a wireless network;

receiving said coded and reformatted digitized speech using a receiver in said mobile terminal and decoding said coded and reformatted digitized speech to obtain decoded speech and an error indication;

combining said error indication with said decoded speech and deformatting the decoded speech and the error indication to obtain speech frames for input to a second vocoder;

using said second vocoder to convert said decoded speech to analog speech signals, including using said error indication to mask errors arising during wireless transmission.

25. The method of claim 24 wherein said first vocoder resides in an Internet Telephony terminal used by said second subscriber.

26. The method of claim 24 wherein said first vocoder resides in an Internet Telephony gateway associated with an Internet Telephony service provider with whom said second subscriber has a subscription.

27. The method of claim 24 wherein said first vocoder resides in an Internet Telephony gateway accessed by said second subscriber via a dial-up line.

28. The method of claim 24 wherein formatting said digitized speech for transmission comprises encrypting said digitized speech using a secret key.

29. The method of claim 24 further comprising producing with said first vocoder digitized speech bits including at least one unused bit for each of a predetermined number of bits representing speech.

30. The method of claim 29 in which digitized speech bits are enciphered using a secret key independently from said at least one unused bit.

31. The method of claim 24 wherein coding of digitized speech for transmission over the wireless network comprises error detection coding.

32. The method of claim 31 in which said error detection coding is applied after enciphering said digitized speech using a cipher key.

33. The method of claim 31 wherein coding of digitized speech further comprises error correction coding.

34. The method of claim 24 wherein combining said error indication with said decoded speech leaves a total number of bits associated with said decoded speech excluding the error indication unchanged.

35. The method of claim 24 wherein combining said error indication with said decoded speech comprises combining said error indication with said at least one unused bit.

36. The method of claim 24 wherein formatting and deformatting preserves a same number of bits from an input of said formatting to an output of said deformatting.

37. The method of claim 36 further comprising verifying with a bit counter that a number of deformatted bits is in agreement with a number of formatted bits.

38. The method of claim 36 further comprising verifying on a byte counter that a number of bytes is in agreement with a number of formatted bytes.

39. The method of claim 24 wherein deformatting comprises deciphering the decoded speech plus error indication prior to inputting said speech and error indication to said second vocoder.

40. The method of claim 24 further comprising locating said second vocoder inside said mobile terminal.

41. The method of claim 24 wherein said second subscriber is also a wireless subscriber.

42. A method for transmitting telephone messages via the Internet between a first subscriber and a second subscriber using a first mobile terminal and a second mobile terminal respectively, comprising:

digitizing speech to be transmitted from one of said subscribers to the other of said subscribers using a first vocoder adapted to a data rate used over a wireless path and formatting and coding said digitized speech for wireless transmission;

receiving said coded and formatted speech at a first wireless network station, decoding said coded speech to obtain decoded speech and a first error indication, and reformatting said digitized speech and first error indication for transmission via the Internet;

receiving said reformatted digitized speech and error indication via the Internet at a second wireless network station and recoding the digitized speech and first error indication for wireless transmission from the second wireless network station to said other subscriber;

receiving said recoded speech and first error indication at said other subscriber and decoding said recoded speech to decode the recoded speech and first error indication to produce a second error indication;

combining said decoded first and second error indications with said decoded speech and deformatting the combined decoded speech plus first and second error indications to obtain speech frames for input to a second vocoder;

using said second vocoder to convert said decoded speech to analog speech signals, including using said first and second error indications to mask errors arising during wireless transmission from said one of said subscribers to said first wireless network station or arising during transmission from said second wireless network station to said other subscriber.

43. The method of claim 42 wherein coding comprises encryption using a secret key followed by error detection coding.

44. The method of claim 43 further including error correction coding.

45. The method of claim 42 wherein said first vocoder produces at least two unused output bits for each predetermined number of output bits representing speech.

46. The method of claim 45 wherein said digitized speech is enciphered independently of said at least two unused bits.

47. The method of claim 42 wherein reformatting of said decoded speech and said first error indication comprises combining said first error indication with a decoded bit corresponding to a first of said at least two unused bits.

48. The method of claim 45 wherein combining of said second error indication with said decoded first error indication and decoded speech comprises combining said second error indication with a decoded bit corresponding to a second of said at least two unused bits.

49. The method of claim 42 wherein deformatting includes deciphering said decoded speech plus said first and second error indications using a secret key.

50. A method of transmitting digitized speech containing a plurality of speech bits from a first terminal to a second terminal, said method comprising:

appending one or more error indication bits to said speech bits;

encrypting said speech bits to obtain encrypted speech bits;

encrypting said error indication bits independently of said speech bits to obtain encrypted error indication bits;

error coding said encrypted speech bits and said encrypted error indication bits to obtain coded bits; and

transmitting said coded bits from said first terminal to said second terminal.

51. The method of claim 50 wherein encrypting said error indication bits independently of said speech bits comprises encrypting said error indication bits as a block separate from said speech bits.

52. The method of claim 50 wherein encrypting said error indication bits independently of said speech bits comprises encrypting said speech bits and error indication bits separately by bitwise encryption.

53. The method of claim 50 further comprising error decoding said coded bits at a third terminal disposed in the transmission path between said first and second termninals, and, if an error is detected, modifying said error indication bits without altering the total number of coded bits.

54. The method of claim 53 wherein modifying said error indication bits is performed without deciphering said encrypted error indication bits.

55. The method of claim 53 further comprising:

transmitting said encrypted speech bits and said encrypted error indication bits as modified by said third terminal to said second terminal;

deciphering said encrypted speech bits and said encrypted error indication bits at said second terminal to obtain said speech bits and said error indication bits respectively; and

speech decoding said speech bits using said error indication bits to mask errors arising during transmission.

56. The method of claim 55 wherein speech decoding said speech bits comprises using said error indication bits to invoke an artificial parameter reconstruction algorithm.