Method and Apparatus for Selecting a Channel Filter for a Communication System

• US 20080101417A1
• Filed: 09/09/2005
• Published: 05/01/2008
• Est. Priority Date: 09/10/2004
• Status: Active Grant

• Current Assignee: Mstar France SAS (MediaTek, Inc.), MStar Semiconductor Incorporated (MediaTek, Inc.), Mstar Software R&D Limited (MediaTek, Inc.)
• Original Assignee: Mstar France SAS (MediaTek, Inc.), MStar Semiconductor Incorporated (MediaTek, Inc.), Mstar Software R&D Limited (MediaTek, Inc.)
• Inventors: Chapman, James, Leach, Martin, Valadon, Cyril
• Granted Patent: US 8,743,910 B2
• Time in Patent Office: Days
• US Class Current: 370/497
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal
• CPC Class Codes: H04B 2001/1054 by changing bandwidth

Abstract

A signal receiver is arranged to process a portion of a received signal in each of a plurality of filter branches and to determine a quality metric for each branch. The configuration of a second filter for processing the entirety of the received signal is subsequently performed according to the determined quality metrics.

Claims

1. Filter apparatus for use in a communications signal receiver, the filter apparatus comprising:

a received signal buffer arranged to store a portion of a received signal;

a plurality of filter assessment branches, each filter assessment branch including a first filter arranged to filter a portion of the received signal stored in the received signal buffer; and

a filter selection unit arranged to receive the output of each filter assessment branch and on a basis of the outputs to select a second filter from a set of filters to filter the received signal.

2. Filter apparatus according to claim 1, wherein the first filter of each filter assessment branch has a different configuration to one another.

3. Filter apparatus according to claim 1, wherein a number of filters in the set from which the second filter is selected is equal to or less than a number of filter assessment branches.

4. Filter apparatus according to claim 1, wherein the selected second filter has a same configuration as the first filter in one of the filter assessment branches.

5. Filter apparatus according to claim 1, wherein the selected second filter comprises the first filter in one of the filter assessment branches.

6. Filter apparatus according to claim 1, wherein each filter assessment branch further includes a filter quality estimation unit arranged to receive the output of the respective first filters and to generate a quality metric indicative of filter performance.

7. Filter apparatus according to claim 6, wherein the filter selection unit is arranged to determine the quality metric corresponding to the filter assessment branch having a best filter performance.

8. Filter apparatus according to claim 7, wherein the set of filters from which the second filter is selected includes a default filter, the default filter corresponding to one of the first filters of the filter assessment branches, and the filter selection unit is further arranged to select the default filter when the corresponding filter assessment branch has the best filter performance.

9. Filter apparatus according to claim 8, wherein when the filter assessment branch having the best filter performance does not correspond to the default filter, the filter selection unit is arranged to calculate a difference measure between the quality metrics of the default filter and the best filter, compare the difference measure with a first threshold value and if the difference measure exceeds the first threshold value, to select the filter having the best filter performance, otherwise to select the default filter.

10. Filter apparatus according to claim 6, wherein the filter selection unit is arranged to determine a difference measure between the quality metrics of a first and second filter assessment branch, compare the difference measure with a second threshold value and, if the difference measure exceeds the second threshold value, to select the filter having the best filter performance.

11. Filter apparatus according to claim 10, wherein the set of filters from which the second filter is selected includes a default filter and the filter selection unit is arranged to select the default filter if the difference measure does not exceed the second threshold value.

12. Filter apparatus according to claim 6, wherein the quality metric comprises an estimate of a residual power of the received signal.

13. Filter apparatus according to claim 12, wherein the filter quality estimation unit comprises a channel impulse response estimation unit arranged to generate an estimate of an impulse response of a signal transmission channel and to apply the estimated channel impulse response to a stored signal substantially identical to at least a portion of the originally transmitted signal.

14. Filter apparatus according to claim 13, wherein the filter quality estimation unit further comprises a residual signal power calculation unit arranged to determine a difference between the filtered received signal and the stored signal to which the estimated impulse response has been applied and to calculate the signal power of the determined difference.

15. A method of filtering a received signal in a communications system, the method comprising:

storing at least a portion of a received signal;

providing at least a portion of the stored received signal to a plurality of filter assessment branches, each filter assessment branch comprising a first filter configuration;

assessing a quality of the filtered signal for each filter assessment branch;

selecting a second filter configuration from a set of filter configurations in dependence of the filter quality assessment; and

applying the received signal to the second filter configuration.

16. A method according to claim 15, wherein the first filter configuration of each filter assessment branch has a different configuration to one another.

17. A method according to claim 15, wherein a number of filter configurations in the set from which the second filter configuration is selected is less than or equal to a number of filter assessment branches.

18. A method according to claim 15, wherein each filter configuration in the set from which the second filter configuration is selected has a same configuration as one of the first filter configurations.

19. A method according to claim 15, wherein the step of selecting the second filter configuration includes determining the filter assessment branch having a best filter performance and selecting a corresponding second filter configuration.

20. A method according to claim 15, the method further comprising:

allocating one of the set of filter configurations as a default second filter configuration, the default second filter configuration corresponding to one of the filter assessment branches;

generating a filter performance value for each of the filter assessment branches; and

if the filter assessment branch to which the default second filter configuration corresponds has a best filter performance value, selecting the default second filter configuration.

21. A method according to claim 20, wherein when the filter assessment branch having the best filter performance value does not correspond to the default second filter configuration, the method further comprises:

calculating a difference measure between the best filter performance value and the filter performance value of the filter assessment branch to which the default second filter configuration corresponds;

comparing the difference measure with a first threshold value; and

if the difference measure exceeds the first threshold value, selecting a second filter configuration corresponding to the filter assessment branch having the best filter performance value, otherwise selecting the default second filter configuration.

22. A method according to claim 15, wherein the method further comprises:

generating a filter performance value for a first and a second filter assessment branch;

calculating a difference measure between quality metrics of the first and second filter assessment branches;

comparing the difference measure with a second threshold value; and

if the difference measure exceeds the second threshold value, selecting the filter from the filter assessment branch having a best filter performance.

23. A method according to claim 22, the method further comprising:

allocating one of the set of filter configurations as a default second filter configuration; and

if the difference value does not exceed the second threshold value, selecting the default second filter configuration.

24. A method according to claim 15, wherein the step of assessing the quality of the filtered signal for each filter assessment branch comprises:

generating an estimate of an impulse response of the communications channel;

applying the estimated channel impulse response to a stored signal that is substantially identical to at least a portion of the originally transmitted signal;

determining the difference between the stored signal to which the estimated channel impulse response has been applied and that the output signal from the first filter configuration; and

calculating the signal power of the determined difference, the signal power being indicative of the filter performance.