Methods, systems and computer program products establishing a communication configuration for a modem connection to compensate for echo noise

• US 6,765,955 B1
• Filed: 10/29/1999
• Issued: 07/20/2004
• Est. Priority Date: 10/29/1999
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Ye, Hua, Ware, Malcolm Scott, Davis, Gordon Taylor, Hwang, Dongming
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): ODOM, CURTIS B
• Application Number:
  US09/430,699
• Time in Patent Office: 1,726 Days
• Field of Search: 375/222, 375/219, 375/224, 370/493, 370/252, 370/468
• US Class Current: 375/222
• CPC Class Codes: H04L 5/1438 Negotiation of transmission parameters prior to communication modified according to link quality H04L1/0001

Abstract

Methods, systems and computer program products for configuring a modem communication session when conditions associated with echo noise on a digitally discontinuous channel are detected are provided. The condition is detected at the local modem by reference to the local modem'"'"'s respective transmit and receive rates. A low transmit rate is an indication of a channel problem. Furthermore, where the transmit rate is also lower than the receive rate, the problem is likely at the remote modem end not just a uniformly noisy channel. This combination of conditions has been found to result, for example, from middle echo noise. Once the remote modem side condition is detected various steps may be taken by the local modem to improve the channel performance including boosting its transmit power (which may raise signal power at the remote modem receiver without affecting the level of echo noise), enabling only a low symbol rate for its transmissions (which may concentrate the signal power in a narrower spectrum band to improve signal power) and/or disabling the use of strong pre-emphasis by the remote modem (which may reduce echo noise by reducing remote modem transmit power over a portion of the spectrum). In particular, these approaches have been found to improve performance of V.90 modems operating in fall back (V.34) mode.

Claims

1. A method for configuring a local modem for a communication session with a remote modem, the method comprising the steps of:

detecting during startup of the communication session a receive data rate from the remote modem and a transmit data rate to the remote modem;

initiating a retrain when the transmit data rate is less than the receive data rate if the transmit data rate is less than a predetermined criterion; and

boosting a transmit power to the remote modem of a transmitter of the local modem during the retrain initiated by the initiating step.

2. The method of claim 1 wherein the communication session is on a digitally discontinuous channel subject to echo noise and wherein the boosting step comprises the step of boosting the transmit power to provide a higher signal to echo noise ratio at the remote modem.

3. The method of claim 2 wherein the initiating step further comprises the step of setting a digital discontinuity flag when the transmit data rate is less than the receive data rate if the transmit data rate is less than the predetermined criterion and wherein the boosting step further comprises the step of boosting the transmit power during the retrain when the digital discontinuity flag is set.

4. The method of claim 1 further comprising the step of selecting a predetermined symbol rate for the transmitter when the transmit data rate is less than the receive data rate if the transmit data rate is less than the predetermined criterion.

5. The method of claim 4 wherein the modem and the remote modem are at least one of a V.34 standard modem and a V.90 standard modem and wherein the predetermined symbol rate is 2400 symbols per second.

6. The method of claim 4 wherein the selecting step further comprises the step of disabling strong pre-emphasis for a transmitter of the remote modem when the transmit data rate is less than the receive data rate if the transmit data rate is less than the predetermined criterion.

7. The method of claim 6 wherein the modem and the remote modem are at least one of a V.34 standard modem and a V.90 standard modem and wherein the disabling step further comprises the step of disabling pre-emphasis indexes of 6 and above.

8. The method of claim 6 wherein the initiating step further comprises the step of setting a digital discontinuity flag when the transmit data rate is less than the receive data rate if the transmit data rate is less than the predetermined criterion and wherein the selecting step comprising the step of selecting a predetermined symbol rate for the transmitter of local modem when the digital discontinuity flag is set and wherein the disabling step comprises the step of disabling strong pre-emphasis for the transmitter of the remote modem when the discontinuity flag is set.

9. The method of claim 6 wherein the boosting step, the selecting step and the disabling step are performed during phase 2 of startup of the communication session.

10. The method of claim 2 wherein the detecting step and the initiating step are performed during phase 4 of startup of the communication session.

11. A method for configuring a local modem for a communication session with a remote modem on a digitally discontinuous channel subject to echo noise, the method comprising the steps of:

detecting during startup of the communication session a receive data rate from the remote modem and a transmit data rate to the remote modern; and

selecting a predetermined symbol rate of 2400 symbols per second for a transmitter of the local modem in a INFO_1a signal when the transmit data rate is less than the receive data rate if the transmit data rate is less than a predetermined criterion;

wherein the local modem and the remote modem are at least one of a V3.4 standard modem and a V.90 standard modem.

12. The method of claim 11 wherein the selecting step further comprises the step of disabling strong pre-emphasis for a transmitter of the remote modem when the transmit data rate is less than the receive data rate if the transmit data rate is less than the predetermined criterion.

13. The method of claim 12 wherein the disabling step further comprises the step of disabling pre-emphasis indexes of 6 and above.

14. The method of claim 12 wherein the initiating step further comprises the step of setting a digital discontinuity flag when the transmit data rate is less than the receive data rate if the transmit data rate is less than the predetermined criterion and wherein the selecting step comprising the step of selecting a predetermined symbol rate for the transmitter of the local modem when the digital discontinuity flag is set and wherein the disabling step comprises the step of disabling strong pre-emphasis for the transmitter of the remote modem when the discontinuity flag is set.

15. A system for configuring a local modem for a communication session with a remote modem, the system comprising:

means for detecting during startup of the communication session a receive data rate from the remote modem and a transmit data rate to the remote modern;

means for initiating a retrain when the transmit data rate is less than the receive data rate if the transmit data rate is less than a predetermined criterion; and

means for boosting a transmit power to the remote modem of a transmitter of the local modem during the retrain initiated by the initiating step.

16. The system of claim 15 wherein the means for initiating further comprises means for setting a digital discontinuity flag when the transmit data rate is less than the receive data rate if the transmit data rate is less than the predetermined criterion and wherein the means for boosting farther comprises means for boosting the transmit power during the retrain when the digital discontinuity flag is set.

17. The system of claim 15 further comprising means for selecting a predetermined symbol rate for the transmitter of the local modem when the transmit data rate is less than the receive data rate if the transmit data rate is less than the predetermined criterion.

18. The system of claim 17 wherein the modem and the remote modem are at least one of a V.34 standard modem and a V.90 standard modem and wherein the predetermined symbol rate is 2400 symbols per second.

19. The system of claim 17 wherein the means for selecting further comprises means for disabling strong pre-emphasis for a transmitter of the remote modem when the transmit data rate is less than the receive data rate if the transmit data rate is less than the predetermined criterion.

20. The system of claim 19 wherein the means for initiating further comprises means for setting a digital discontinuity flag when the transmit data rate is less than the receive data rate if the transmit data rate is less than the predetermined criterion and wherein the means for selecting further comprises means for selecting a predetermined symbol rate for the transmitter of the local modem when the digital discontinuity flag is set and wherein the means for disabling further comprises means for disabling strong pre-emphasis for the transmitter of the remote modem when the discontinuity flag is set.

21. A system for configuring a local modem for a communication session with a remote modem on a digitally discontinuous channel subject to echo noise, the system comprising:

means for detecting during startup of the communication session a receive data rate from the remote modem and a transmit data rate to the remote modem; and

means for selecting a predetermined symbol rate of 2400 symbols per second for a transmitter of the local modem by specifying the symbol rate in a INFO_1a signal when the transmit data rate is less than the receive data rate if the transmit data rate is less than a predetermined criterion;

wherein the local modem and the remote modem are at least one of a V.34 standard modem and a V.90 standard modem.

22. The system of claim 21 wherein the means for selecting further comprises means for disabling strong pre-emphasis for a transmitter of the remote modem when the transmit data rate is less than the receive data rate if the transmit data rate is less than the predetermined criterion.

23. A computer program product for configuring a local modem for a communication session with a remote modem, comprising:

a computer readable storage medium having computer readable program code means embodied therein, the computer readable code means comprising;

computer readable code that detects during startup of the communication session a receive data rate from the remote modem and a transmit data rate to the remote modem;

computer readable code that initiates a retrain when the transmit data rate is less than the receive data rate if the transmit data rate is less than a predetermined criterion; and

computer readable code that boosts a transmit power to the remote modem of a transmitter of the local modem during the retrain initiated by the initiating step.

24. The computer program product of claim 23 wherein the computer readable code that initiates further comprises computer readable code that sets a digital discontinuity flag when the transmit data rate is less than the receive data rate if the transmit data rate is less than the predetermined criterion and wherein the computer readable code that boosts farther comprises computer readable code that boosts the transmit power during the retrain when the digital discontinuity flag is set.

25. The computer program product of claim 23 further comprising computer readable code that selects a predetermined symbol rate for the transmitter when the transmit data rate is less than the receive data rate if the transmit data rate is less than the predetermined criterion.

26. The computer program product of claim 25 wherein the modem and the remote modem are at least one of a V.34 standard modem and a V.90 standard modem and wherein the predetermined symbol rate is 2400 symbols per second.

27. The computer program product of claim 25 wherein the computer readable code that selects further comprises computer readable code that disables strong pre-emphasis for a transmitter of the remote modem when the transmit data rate is less than the receive data rate if the transmit data rate is less than the predetermined criterion.

28. The computer program product of claim 27 wherein the computer readable code that initiates further comprises computer readable code that sets a digital discontinuity flag when the transmit data rate is less than the receive data rate if the transmit data rate is less than the predetermined criterion and wherein the computer readable code that selects further comprises computer readable code that selects a predetermined symbol rate for the transmitter of the local modem when the digital discontinuity flag is set and wherein the computer readable code that disables farther comprises computer readable code that disables strong pre-emphasis for the transmitter of the remote modem when the discontinuity flag is set.

29. A computer program product for configuring a local modem for a communication session with a remote modem on a digitally discontinuous channel subject to echo noise, the computer program product comprising:

a computer readable storage medium having computer readable program code means embodied therein, the computer readable code means comprising;

computer readable code that detects during startup of the communication session a receive data rate from the remote modem and a transmit data rate to the remote modem; and

computer readable code that selects a predetermined symbol rate of 2400 symbols per second for a transmitter of the local modem in a INFO_1a signal when the transmit data rate is less than the receive data rate if the transmit data rate is less than a predetermined criterion;

wherein the local modem and the remote modem are at least one of a V.34 standard modem and a V.90 standard modem.

30. The computer program product of claim 29 wherein the computer readable code that selects further comprises computer readable code that disables strong pre-emphasis for a transmitter of the remote modem when the transmit data rate is less than the receive data rate if the transmit data rate is less than the predetermined criterion.