Modems having a dual power mode capability and methods of operating same

• US 6,792,040 B1
• Filed: 10/29/1999
• Issued: 09/14/2004
• 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, Neeser, Fredy D., Dholakia, Ajay, Davis, Gordon Taylor
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): WANG, TED M
• Application Number:
  US09/430,678
• Time in Patent Office: 1,782 Days
• Field of Search: 375/242, 375/222, 375/231, 375/221, 375/219, 375/146, 375/220, 714/704, 370/523, 370/474, 370/420, 455/450, 455/76
• US Class Current: 375/222
• CPC Class Codes: H03G 3/3036 in high-frequency amplifiers or in frequency-changers H03G3/3052, H03G3/32, H03G3/34 take precedence
• CPC Class Codes: H04L 25/03063 using fractionally spaced delay lines or combinations of fractionally and integrally spaced taps
• CPC Class Codes: H04L 5/1438 Negotiation of transmission parameters prior to communication modified according to link quality H04L1/0001
• CPC Class Codes: H04M 11/06 Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors

Abstract

Modems, methods, and computer program products provide a dual power mode capability in which a maximum power limit is determined for a received signal and, based on that determination, at least one modem operational parameter is adjusted and/or digital impairment learning (DIL) sequence is selected. Adjustments made to the operational parameters may allow a modem to operate in a high power mode to achieve a higher downstream data rate. The higher downstream data rate may be attributed to an improved SNR resulting from an increase in data transmission power. Moreover, the modem may also operate in a normal power mode where the operational parameters may be set to maximize the client modem receiver'"'"'s dynamic range. By selecting the DIL sequence based on the power limit, a DIL signal containing symbols having power levels within the power limit may be selected.

Claims

1. A dual power mode modem, comprising:

means for determining a power limit for a received signal;

an adjustable automatic gain control (AGC) component that is responsive to the means for determining the power limit;

an adjustable remote retrain detection component coupled to the AGC component and being responsive thereto;

an adjustable decision feedback equalizer (DFE) that is responsive to the AGC component and the means for determining the maximum power limit, comprising;

a feed forward section that generates a feed forward output signal;

a feed back section that generates a feed back output signal;

an adder that subtracts the feed back output signal from the feed forward output signal to generate an adder output signal;

a first adjustable scaling unit that couples the feed back output signal to the adder and applies a first, adjustable scaling factor thereto;

a second adjustable scaling unit that applies a second, adjustable scaling factor to the adder output signal; and

an adaptive echo canceller coupled to the adjustable DFE and being responsive to the means for determining the power limit.

2. A dual power mode modem as recited in claim 1, further comprising:

means for adjusting a plurality of operational parameters for the modem based on the power limit.

3. A dual power mode modem as recited in claim 2, wherein the plurality of operational parameters comprise:

a target power level of the adjustable AGC component;

a retrain power threshold used by the adjustable remote retrain detection component;

an adaptation step size used to adapt filter coefficients associated with the adaptive echo canceller; and

an adaptation step size used to adapt filter coefficients associated with the feed forward section.

4. A dual power mode modem as recited in claim 3, further comprising:

means for scaling the target power level of the adjustable AGC component;

means for scaling the retrain power threshold;

means for scaling the adaptation step size used to adapt filter coefficients associated with the adaptive echo canceller;

means for scaling the adaptation step size used to adapt filter coefficients associated with the feed forward section;

means for setting the first scaling factor to a first value; and

means for setting the second scaling factor to a second value.

5. A dual power mode modem, comprising:

means for determining a power limit for a received signal;

an adaptive digital filter; and

means for adjusting at least one operational parameter for the modem based on the power limit;

wherein the at least one operational parameter comprises an adaptation step size used to adapt coefficients associated with the adaptive digital filter.

6. A dual power mode modem as recited in claim 5, wherein the means for determining the power limit comprises:

means for receiving a message from a remote modem that contains the power limit.

7. A dual power mode modem as recited in claim 5, further comprising:

an automatic gain control (AGC) component; and

wherein the at least one operational parameter comprises a target power level of the AGC component.

8. A dual power mode modem as recited in claim 7, further comprising:

a remote retrain detection component coupled to the AGC component; and

wherein the at least one operational parameter comprises a retrain power threshold used by the remote retrain detection component.

9. A dual power mode modem as recited in claim 5, wherein the at least one operational parameter comprises at least one scaling factor applied to an internal signal of the modem.

10. A dual power mode modern as recited in claim 5, wherein the means for adjusting at least one operational parameter comprises:

means for adjusting a plurality of operational parameters for the modem based on the power limit.

11. A dual power mode modem, comprising:

means for determining a power limit for a received signal;

means for classifying the power limit as one of high and normal;

means for selecting a digital impairment learning (DIL) sequence based on the power limit comprising means for selecting a long DIL sequence if the power limit is high.

12. A dual power mode modem as recited in claim 11, wherein the means for determining the power limit comprises:

means for receiving a message from a remote modem that contains the power limit.

13. A dual power mode modem as recited in claim 11, wherein the long DIL sequence comprises:

a short DIL sequence section comprising a first subset of symbols selected from a plurality of symbols;

a guard segment; and

a high power section comprising a second subset of symbols selected from the plurality of symbols, each of the plurality of symbols having a power level associated therewith such that the power levels associated with the second subset of symbols are greater than the power levels associated with the first subset of symbols.

14. A dual power mode modem as recited in claim 13, wherein the means for selecting the DIL sequence comprises:

means for selecting the short DIL sequence if the power limit is normal.

15. A dual power anode modem as recited in claim 13, wherein the plurality of symbols comprises a plurality of Ucodes ranging from 0 to 127, the first subset of symbols comprises the Ucodes 0 through 110, and the second subset of symbols comprises the Ucodes 111 through 120.

16. A method of operating a dual power mode modem comprising an adaptive digital filters, comprising the steps of:

determining a power limit for a received signal; and

adjusting at least one operational parameter for the modem based on the power limit wherein the at least one operational parameter comprises an adaptation step size used to adopt filter coefficients associated with the adaptive digital filter.

17. A method as recited in claim 16, wherein the step of determining the power limit comprises the step of:

receiving a message from a remote modem that contains the power limit.

18. A method as recited in claim 16, wherein the modem further comprises an automatic gain control (AGC) component and the at least one operational parameter comprises a target power level of the AGC component.

19. A method as recited in claim 18, wherein the modem further comprises a remote retrain detection component coupled to the AGC component and the at least one operational parameter comprises a retrain power threshold used by the remote retrain detection component.

20. A method as recited in claim 16, wherein the at least one operational parameter comprises at least one scaling factor applied to an internal signal of the modem.

21. A method as recited in claim 16, wherein the step of adjusting at least one operational parameter comprises the step of:

adjusting a plurality of operational parameters for the modem based on the power limit.

22. A method as recited in claim 21, wherein the modem comprises an automatic gain control (AGC) component, a remote retrain detection component, an echo canceller, a decision feedback equalizer (DFE) that includes a feed forward section that generates a feed forward output signal and a feed back section that generates a feed back output signal, an adder that subtracts the feed back output signal from the feed forward output signal to generate an adder output signal, a first scaling unit that couples the feed back output signal to the adder, a slicer, and a second scaling unit that couples the adder output signal to the slicer, the AGC component and the echo canceller each being coupled to the DFE, and the remote retrain detection component being coupled to the AGC component, and wherein the plurality of operational parameters comprise:

a target power level of the AGC component;

a retrain power threshold used by the remote retrain detection component;

an adaptation step size used to adapt filter coefficients associated with the echo canceller;

an adaptation step size used to adapt filter coefficients associated with the feed forward section;

a first scaling factor applied by the first scaling unit to the feed back signal; and

a second scaling factor applied by the second scaling unit to the adder output signal.

23. A method as recited in claim 22, wherein the step of adjusting the plurality of operational parameters comprises the steps of:

scaling the target power level of the AGC component;

scaling the retrain power threshold;

scaling the adaptation step size used to adapt filter coefficients associated with the echo canceller;

scaling the adaptation step size used to adapt filter coefficients associated with the feed forward section;

setting the first scaling factor to a first value; and

setting the second scaling factor to a second value.

24. A method of operating a dual power mode modem, comprising the steps of:

determining a power limit for a received signal;

classifying the power limit as one of high and normal;

selecting a digital impairment learning (DIL) sequence based on the power limit comprising selecting a long DIL sequence if the power limit high.

25. A method as recited in claim 24, wherein the step of determining the power limit comprises the step of:

receiving a message from a remote modem that contains the power limit.

26. A method as recited in claim 24, wherein the long DIL sequence comprises:

a short DIL sequence section comprising a first subset of symbols selected from a plurality of symbols;

a guard segment; and

a high power section comprising a second subset of symbols selected from the plurality of symbols, each of the plurality of symbols having a power level associated therewith such that the power levels associated with the second subset of symbols are greater than the power levels associated with the first subset of symbols.

27. A method as recited in claim 26, wherein the step of selecting the DIL sequence comprises the step of:

selecting the short DIL sequence if the power limit is normal.

28. A method as recited in claim 26, wherein the plurality of symbols comprises a plurality of Ucodes ranging from 0 to 122, the first subset of symbols comprises the Ucodes 0 through 110, and the second subset of symbols comprises the Ucodes 111 through 120.

29. A computer program product for operating a dual power rode modem comprising an adaptive digital filter, comprising:

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

computer readable program code for determining a power limit for a received signal; and

computer readable program code for adjusting at least one operational parameter for the modem based on the power limit wherein the at least one operational parameter comprises an adaptation step size used to adapt coefficients associated with the adaptive digital filter.

30. A computer program product as recited in claim 29, wherein the computer readable program code for determining the power limit comprises:

computer readable program code for receiving a message from a remote modem that contains the power limit.

31. A computer program product as recited in claim 29, wherein the modem further comprises an automatic gain control (AGC) component and wherein the at least one operational parameter comprises a target power level of the AGC component.

32. A computer program product as recited in claim 31, wherein the modem further comprises a remote retrain detection component coupled to the AGC component and wherein the at least one operational parameter comprises a retrain power threshold used by the remote retrain detection component.

33. A computer program product as recited in claim 29, wherein the at least one operational parameter comprises at least one scaling factor applied to an internal signal of the modem.

34. A computer program product as recited in claim 29, wherein the computer readable program code for adjusting at least one operational parameter comprises:

computer readable program code for adjusting a plurality of operational parameters for the modem based on the power limit.

35. A computer program product as recited in claim 34, wherein the modem comprises an automatic gain control (AGC) component, a remote retrain detection component, an echo canceller, a decision feedback equalizer (DFE) that includes a feed forward section that generates a feed forward output signal and a feed back section that generates a feed back output signal, an adder that subtracts the feed back output signal from the feed forward output signal to generate an adder output signal, a first scaling unit that couples the feed back output signal to the adder, a slicer, and a second scaling unit that couples the adder output signal to the slicer, the AGC component and the echo canceller each being coupled to the DFE, and the remote retrain detection component being coupled to the AGC component, and wherein the plurality of operational parameters comprise:

a target power level of the AGC component;

a retrain power threshold used by the remote retrain detection component;

an adaptation step size used to adapt filter coefficients associated with the echo canceller;

an adaptation step size used to adapt filter coefficients associated with the feed forward section;

a first scaling factor applied by the fist scaling unit to the feed back signal; and

a second scaling factor applied by the second scaling unit to the adder output signal.

36. A computer program product as recited in claim 35, wherein the computer readable program code for adjusting the plurality of operational parameters comprises:

computer readable program code for scaling the target power level of the AGC component;

computer readable program code for scaling the retrain power threshold;

computer readable program code for scaling the adaptation step size used to adapt filter coefficients associated with the echo canceller;

computer readable program code for scaling the adaptation step size used to adapt filter coefficients associated with the feed forward section;

computer readable program code for setting the first scaling factor to a first value; and

computer readable program code for setting the second scaling factor to a second value.

37. A computer program product for operating a dual power mode modem, comprising:

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

computer readable program code for determining a power limit for a received signal and classifying the power limit as one of high and normal; and

computer readable program code for selecting a digital impairment learning (DIL) sequence based on the power limit comprising computer readable program code for selecting a long DIL sequence if the power limit is high.

38. A computer program product as recited in claim 37, wherein the computer readable program code for determining the power limit comprises:

computer readable program code for receiving a message from a remote modem that contains the power limit.

39. A computer program product as recited in claim 37, wherein the long DIL sequence comprises:

a short DIL sequence section comprising a first subset of symbols selected from a plurality of symbols;

a guard segment; and

a high power section comprising a second subset of symbols selected from the plurality of symbols, each of the plurality of symbols having a power level associated therewith such that the power levels associated with the second subset of symbols are greater than the power levels associated with the first subset of symbols.

40. A computer program product as recited in claim 39, wherein the computer readable program code for selecting the DIL sequence comprises:

computer readable program code for selecting the short DIL sequence if the power limit is normal.

41. A computer program product as recited in claim 39, wherein the plurality of symbols comprises a plurality of Ucodes ranging from 0 to 122, the first subset of symbols comprises the Ucodes 0 through 110, and the second subset of symbols comprises the Ucodes 111 through 120.