Enhanced channel estimation

• US 6,442,129 B1
• Filed: 12/06/1999
• Issued: 08/27/2002
• Est. Priority Date: 12/06/1999
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Intellon Corporation (Qualcomm, Inc.)
• Inventors: Mashburn, Harper Brent, Yonge, Lawrence W. III
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): Tran, Maikhanh
• Application Number:
  US09/455,110
• Time in Patent Office: 995 Days
• Field of Search: 370/203, 370/204-205, 370/206-207, 370/208, 370/210, 370/252, 370/332-333, 375/200, 375/260-261, 375/264, 375/267, 375/268, 375/271-272, 375/273, 375/279, 375/308, 375/329, 375/222, 375/259, 375/295, 375/316, 375/227, 375/346-348
• US Class Current: 370/204
• CPC Class Codes: H04L 5/0044 allocation of payload

Abstract

A scheme for identifying usable carriers for a particular modulation type and selecting, if possible, a modulation type for modulation of OFDM symbol block associated with data packets in a standard transmission mode based on data channel conditions. Channel estimation for an OFDM symbol block received by a receiving network node over a data channel during a packet transmission by a transmitting network node generates information indicative of noise events on symbols and carriers in the OFDM block, the generated information being related to modulation types available for the standard transmission mode, and determines from the generated information if at least one of the modulation types available for the standard transmission mode may be used for a next data transmission over the data channel by the transmitting network node using the standard transmission mode. One of the modulation types is selected if it is determined that at least one of the modulation types may be used. A channel map identifying good carriers for the selected modulation type is produced and stored in memory. If it is determined that one of the modulation modes for the standard transmission mode may not be selected, then a robust transmission mode is chosen instead. The robust transmission mode transmits more reliably (albeit at a lower data rate) than the standard transmission mode. The channel map associated with the standard transmission mode,if produced, or the selection of the robust transmission mode is conveyed to the transmitting network node.

Claims

1. A method of performing channel estimation for an OFDM symbol block received by a receiving network node over a data channel during a packet transmission by a transmitting network node comprising:

generating for available modulation types information indicative of noise events that occurred in the OFDM symbol block, the information being generated across symbols and carriers in the OFDM symbol block; and

determining from the generated information which of the available modulation types is to be used for a next data transmission over the data channel by the transmitting network node.

2. The method of claim 1, wherein generating comprises:

computing average symbol phase noise values for each of the symbols and average carrier phase noise values for each of the carriers.

3. The method of claim 2, wherein generating further comprises:

determining one or more symbol counts, each corresponding to a different impulse noise symbol threshold and providing a number of average symbol phase noise values exceeding such different impulse noise symbol threshold.

4. The method of claim 2, wherein generating further comprises:

determining carrier counts for the available modulation types from the computed average carrier phase noise values, each carrier count indicative of a number of the computed average carrier phase noise values exceeding a carrier threshold corresponding to a different one of the modulation types.

5. The method of claim 4, wherein each carrier count is further indicative of a number of carrier values exceeding a jammer detection threshold.

6. The method of claim 5, where generating further comprises:

generating for each of the available modulation types a corresponding channel map, the channel map identifying as good those carriers that contributed to the carrier counts for a one of the available modulation types to which the channel map corresponds.

7. The method of claim 5, wherein determining comprises:

using the carrier and one or more symbols counts to determine if one or more of the available modulation types is acceptable for use with a standard transmission mode over the channel.

8. The method of claim 7, wherein using comprises:

testing the carrier and one or more symbol counts against criteria specified for each of the available modulation types.

9. The method of claim 7, wherein determining further comprises:

computing data rates of the one or more of the available modulation types determined to be acceptable for use with the standard transmission mode over the channel; and

selecting the fastest of the one or more available modulation types determined to be acceptable for use with the standard transmission over the channel.

10. The method of claim 9, further comprising:

storing the channel map corresponding to the selected modulation type in memory.

11. The method of claim 9, further comprising:

providing the channel map corresponding to the selected modulation type to the transmitting network node.

15. The method of claim 4, wherein generating further comprises:

generating average threshold margins for each of the carrier counts to indicate the average amount by which the corresponding carrier threshold was exceeded.

16. The method of claim 1, wherein the selected modulation type is the same for all of the carriers.

12. A method of performing channel estimation for an OFDM symbol block received by a receiving network node over a data channel during a packet transmission by a transmitting network node comprising:

generating for available modulation types information indicative of noise events that occurred in the OFDM symbol block;

determining from the generated information which of the available modulation types is to be selected for use in a standard transmission mode for a next data transmission over the data channel by the transmitting network node; and

selecting an alternative, second transmission mode if it is determined that any of the modulation types for the standard transmission mode may not be selected, the second transmission mode having an associated modulation type and being capable of a more robust transmission at a lower data rate than the modulation types used in the standard transmission mode.

13. The method of claim 12, wherein determining further comprises:

conveying the selected alternative, second transmission mode to the transmitting network node.

14. The method of claim 12, wherein the associated modulation type is the slowest of the available modulation types.

17. An apparatus for performing channel estimation for an OFDM symbol block received by a receiving network node over a data channel during a packet transmission by a transmitting network node comprising:

means for generating for available modulation types information indicative of noise events that occurred in the OFDM symbol block;

means for determining from the generated information which of the available modulation types is to be used for a next data transmission over the data channel by the transmitting network node;

and

wherein means for generating includes means for generating the information across symbols and carriers in the OFDM symbol block.

18. The apparatus of claim 17, wherein the means for generating comprises:

means for computing average symbol phase noise values for each of the symbols and average carrier phase noise values for each of the carriers.

19. The apparatus of claim 18, wherein the means for generating further comprises:

means for determining one or more symbol counts, each corresponding to a different impulse noise symbol threshold and providing a number of average symbol phase noise values exceeding such different impulse noise symbol threshold.

20. the apparatus of claim 18, wherein each carrier count is further indicative of a number of carrier values exceeding a jammer detection threshold.

21. The apparatus of claim 20, wherein the means for generating further comprises:

means for generating for each of the available modulation types a corresponding channel map, the channel map identifying as good those carriers that contributed to the carrier counts for a one of the available modulation types to which the channel map corresponds.

22. The apparatus of claim 20, wherein the means for determining comprises:

means for using the carrier and one or more symbols counts to determine if one of more of the available modulation types is acceptable for use with a standard transmission mode over the channel.

23. The apparatus of claim 22, wherein the means for using comprises:

means for testing the carrier and one or more symbol counts against criteria specified for each of the available modulation types.

24. The apparatus of claim 22, wherein the means for determining further comprises:

means for computing data rates of the one or more of the available modulation types determined to be acceptable for use with the standard transmission mode over the channel; and

means for selecting the fastest of the one or more available modulation types determined to be acceptable for use with the standard transmission over the channel.

25. The apparatus of claim 24, further comprising:

means for storing the channel map corresponding to the selected modulation type in memory.

26. The apparatus of claim 24, further comprising:

providing the channel map corresponding to the selected modulation type to the transmitting network node.

30. The apparatus of claim 20, wherein the means for generating further comprises:

means for generating average threshold margins for each of the carrier counts to indicate the average amount by which the corresponding carrier threshold was exceeded.

31. The apparatus of claim 17, wherein the selected modulation type is the same for all of the carriers.

33. The apparatus of claim 18, wherein the means for generating further comprises:

means for determining carrier counts for the available modulation types from the computed average carrier phase noise values, each carrier count indicative of a number of the computed average carrier phase noise values exceeding a carrier threshold corresponding to a different one of the modulation types.

27. An apparatus for performing channel estimation for an OFDM symbol block received by a receiving network node over a data channel during a packet transmission by a transmitting network node comprising:

means for generating for available modulation types information indicative of noise events that occurred in the OFDM symbol block;

means for determining from the generated information which of the available modulation types is to be selected for use in a standard transmission mode for a next data transmission over the data channel by the transmitting network node; and

means for selecting an alternative, second transmission mode if it is determined that any of the modulation types for the standard transmission mode may not be selected, the second transmission mode having an associated modulation type and being capable of a more robust transmission at a lower data rate than the modulation types used in the standard transmission mode.

28. The apparatus of claim 27, wherein the means for determining further comprises:

means for conveying the selected alternative, second transmission mode to the transmitting network node.

29. The apparatus of claim 27, wherein the associated modulation type is the slowest of the available modulation types.

32. A computer program residing on a computer-readable medium for performing channel estimation for an OFDM symbol block received by a receiving network node over a data channel during a packet transmission by a transmitting network node, the computer program product comprising instructions causing a computer to:

generate for available modulation types information indicative of noise events that occurred in the OFDM symbol block, the information being generated across symbols and carriers in the OFDM symbol block; and

determine from the generated information which of the available modulation types is to be used for a next data transmission over the data channel by the transmitting network node.