ADAPTIVE CHANNEL PREDICTION AND MITIGATING INTERFERENCE IN OFDM SYSTEMS

• US 20160285664A1
• Filed: 03/14/2016
• Published: 09/29/2016
• Est. Priority Date: 12/18/2013
• Status: Active Grant

• Current Assignee: Maxlinear Incorporated
• Original Assignee: Intel Corporation
• Inventors: ARAMBEPOLA, BERNARD, SHUKLA, PARVEEN K., HEWAVITHANA, THUSHARA
• Granted Patent: US 9,742,610 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04L 25/0218 with detection of nulls
• CPC Class Codes: H04L 25/022 of frequency response
• CPC Class Codes: H04L 25/0232 by interpolation between sounding signals
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04L 27/2607 Cyclic extensions
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 27/2646 using feedback from receiver for adjusting OFDM transmission parameters, e.g. transmission timing or guard interval length
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 27/2665 Fine synchronisation, e.g. by positioning the FFT window
• CPC Class Codes: H04L 27/2678 using cyclostationarities, e.g. cyclic prefix or postfix
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT

Abstract

One embodiment provides an apparatus. The apparatus includes an optimization module configured to determine a guard interval remainder based, at least in part on a comparison of an allowable microreflection interference level and an actual microreflection interference level; and a windowing module configured to window an OFDM (orthogonal frequency division multiplexed) symbol utilizing the guard interval remainder. The apparatus may further include a channel estimator module configured to determine a predicted channel frequency response based, at least in part, on a probing symbol; and a pre-equalizer module configured to pre-equalize the OFDM symbol based, at least in part, on the predicted channel frequency response.

Claims

1-24. -24. (canceled)

25. An apparatus, comprising:

pre-equalizer circuitry to pre-equalize an orthogonal frequency division multiplexed (OFDM) symbol based, at least in part, on a predicted channel frequency response, wherein the predicted channel frequency response is determined based, at least in part, on a probing symbol;

optimization circuitry to determine a guard interval remainder based, at least in part, on a comparison of an allowable microreflection interference level and an actual microreflection interference level; and

windowing circuitry to window the OFDM symbol utilizing the guard interval remainder.

26. The apparatus of claim 25, wherein the optimization circuitry is further configured to determine the allowable microreflection interference level based on a modulation technique associated with the OFDM symbol.

27. The apparatus of claim 25, wherein the optimization circuitry is further configured to determine the actual microreflection interference level based, at least in part, on a channel impulse response.

28. The apparatus of claim 25, wherein the pre-equalizer circuitry is further configured to pre-equalize the probing symbol.

29. The apparatus of claim 25, wherein the predicted channel frequency response is time varying with non-time varying components removed.

30. A method, comprising:

pre-equalizing, by pre-equalizer circuitry, or equalizing, by equalizer circuitry, or both pre-equalizing and equalizing, an orthogonal frequency division multiplexed (OFDM) symbol based, at least in part, on a predicted channel frequency response, wherein the predicted channel frequency response is determined, at least in part, on a probing symbol;

determining, by optimization circuitry, a guard interval remainder based, at least in part on a comparison of an allowable microreflection interference level and an actual microreflection interference level; and

windowing, by windowing circuitry, the OFDM symbol utilizing the guard interval remainder.

31. The method of claim 30, further comprising:

determining, by the optimization circuitry, the allowable microreflection interference level based on a modulation technique associated with the OFDM symbol.

32. The method of claim 30, further comprising:

determining, by the optimization circuitry, the actual microreflection interference level based, at least in part, on a channel impulse response.

33. The method of claim 30, further comprising:

pre-equalizing, by the pre-equalizer circuitry, the probing symbol.

34. The method of claim 30, wherein the predicted channel frequency response is time varying with non-time varying components removed.

35. A system comprising, one or more non-transitory computer memories having stored thereon, individually or in combination, instructions that when executed by one or more processors result in the following operations comprising:

pre-equalizing or equalizing or both pre-equalizing and equalizing, an orthogonal frequency division multiplexed (OFDM) symbol based, at least in part, on a predicted channel frequency response, wherein the predicted channel frequency response is determined based, at least in part, on a probing symbol;

determining a guard interval remainder based, at least in part on a comparison of an allowable microreflection interference level and an actual microreflection interference level; and

windowing the OFDM symbol utilizing the guard interval remainder;

36. The system of claim 35, wherein the instructions that when executed by the one or more processors results in the following additional operations comprising:

determining the allowable microreflection interference level based on a modulation technique associated with the OFDM symbol.

37. The system of claim 35, wherein the instructions that when executed by the one or more processors results in the following additional operations comprising:

determining the actual microreflection interference level based, at least in part, on a channel impulse response.

38. The system of claim 35, wherein the instructions that when executed by the one or more processors results in the following additional operations comprising:

pre-equalizing the probing symbol.

39. The system of claim 35, wherein the predicted channel frequency response is time varying with non-time varying components removed.