Channel quality index feedback reduction for broadband systems
Systems and methodology for exploiting channel correlation in time and/or frequency to reduce CQI feedback in wireless communications systems. By compressing CQI feedback at the receiver to reduce redundancy in CQI feedback information that results from the channel correlation, the average feedback rate is reduced. In various embodiments, redundancy in time may be removed from the CQI feedback by monitoring variations of the CQI information in time at the receiver so that CQI information for a given CQI reporting instance is communicated to the transmitter only if it differs from the CQI information for the previous CQI reporting instance. Otherwise, no feedback is performed. In other embodiments, CQI feedback is compressed by performing a discrete cosine transform (DCT) on the CQI data.
1. A method for processing signals in a wireless communication system comprising a plurality of transmission channels, the method comprising:
detecting at least one change in channel state information for a plurality of reporting instances; and
ranking the detected at least one change in channel state information; and
generating a compressed set of channel quality indicator (CQI) information, the compressed set configured to omit at least one CQI information based on the ranking;
wherein:
each of the plurality of transmission channels comprises one or more CQI parameters; and
the compressed set of CQI information comprises information useful for transmitting data from a transmitting device to a receiving device over one or more of the plurality of transmission channels.
2. The method of claim 1 , wherein the compressed set of CQI information comprises only CQI information that meets one or more predetermined selection metrics.
3. The method of claim 2 , wherein the one or more predetermined selection metrics are dynamically changed between a first CQI reporting instance and a second CQI reporting instance.
4. The method of claim 3 , wherein the generating of the compressed set of CQI information further comprises:
ranking CQI values for a first plurality of candidate clusters having a changed CQI information;
selecting therefrom a subset of clusters, the selecting comprising identifying the candidate clusters having the largest change in CQI magnitude; and
using the changed CQI information of the subset of clusters to generate the compressed set of CQI information.
5. The method of claim 1 , wherein changes between a first set of CQI information and a second set of CQI information are detected using at least a CQI transition detector.
6. The method of claim 1 , wherein changes between a first set of CQI information and a second set of CQI information are detected by:
generating first and second sets of transform coefficients based at least in part on a Multiple Input Multiple Output (MIMO) transform; and
detecting changes in the second set of transform coefficients with respect to the first set of transform coefficients.
7. The method of claim 6 , wherein the MIMO transform comprises a discrete cosine transform.
8. The method of claim 1 , further comprising transmitting the compressed set of CQI information to the transmitting device using an index corresponding to CQI information entries in one or more predefined codebooks.
9. A receiver for use in a wireless communication system, comprising:
a channel state change detector configured to detect changes in channel state information in a plurality of reporting instances, the channel state change detector comprising:
a discrete cosine transform (DCT) apparatus configured to calculate DCT coefficients; and
a processor configured to detect changes in calculated DCT coefficients;
a channel quality indicator (CQI) compression apparatus configured to generate a compressed set of CQI information, the compressed set of CQI information configured to remove redundant CQI information; and
a transmitter configured to transmit the compressed set of CQI information over a channel.
10. The receiver of claim 9 , wherein the compressed set of CQI information comprises only CQI information that meets predetermined selection metrics.
11. The receiver of claim 10 , wherein the predetermined selection metrics are dynamically changed form one CQI reporting instance to another CQI reporting instance.
12. The receiver of claim 9 , wherein the compressed set of CQI information is transmitted from the receiver to a transmitting device.
13. The receiver of claim 9 , wherein the compressed set of CQI information comprises carrier to interference plus noise ratio (CJNR) information.
14. The receiver of claim 9 , wherein the compressed set of CQI information comprises an index corresponding to CQI information entries in codebooks in the receiver and the transmitter.
15. The receiver of claim 9 , wherein the channel over which the transmitter is configured to transmit the compressed set of CQI information comprises a feedback channel.
16. A transmitter for use in a wireless communication system, comprising:
first apparatus configured to receive a compressed set of transmission channel state information; and
second apparatus configured to use the compressed set of transmission channel state information to generate signal processing information to transmit data from the transmitter to a receiver over a transmission channel;
wherein:
the compressed set of transmission channel state information comprises information generated at the receiver, and information derived from detected changes in transmission channel state information; and
the compressed set of transmission channel state information comprises only transmission channel state information that meets predetermined selection metrics, the predetermined selection metrics being configured to remove at least one channel quality indicator.
17. The transmitter of claim 16 , wherein the predetermined selection metrics are dynamically changed from one channel quality indicator (CQI) reporting instance to another CQI reporting instance.
18. The transmitter of claim 16 , wherein the compressed set of transmission channel state information is transmitted from the receiver to the transmitter using an index corresponding to channel quality indicator (CQI) information entries in codebooks in the receiver and the transmitter.
19. A method for processing signals in a wireless communication system comprising a plurality of transmission channels, the method comprising:
detecting at least one change in channel state information for a plurality of reporting instances;
ranking the detected at least one change in channel state information;
generating a compressed set of channel quality indicator (CQI) information, the compressed set configured to omit redundant CQI information, wherein:
each of the plurality of transmission channels comprises one or more CQI parameters;
the compressed set of CQI information comprises information useful for transmitting data from a transmitting device to a receiving device over one or more of the plurality of transmission channels; and
transmitting the compressed set of CQI information to the transmitting device using an index corresponding to CQI information entries in one or more predefined codebooks.
20. The method of claim 19 , wherein the compressed set of CQI information comprises only CQI information that meets one or more predetermined selection metrics.
21. The method of claim 20 , wherein the method further comprises dynamically changing the one or more predetermined selection metrics between a first CQI reporting instance and a second CQI reporting instance.
22. The method of claim 21 , wherein the generating of the compressed set of CQI information further comprises:
ranking CQI values for a first plurality of candidate clusters having changed CQI information;
selecting therefrom a subset of clusters, the selecting comprising identifying the candidate clusters having the largest change in CQI magnitude; and
using the changed CQI information of the subset of clusters to generate the compressed set of CQI information.
23. The method of claim 20 , wherein the one or more predetermined selection metrics comprise selecting CQI data related to a group of candidate clusters with the largest CQI values.
24. The method of claim 19 , wherein changes between a first set of CQI information and a second set of CQI information are detected using at least a CQI transition detector.
25. The method of claim 19 , wherein changes between a first set of CQI information and a second set of CQI information are detected by:
generating first and second sets of transform coefficients based at least in part on a Multiple Input Multiple Output (MIMO) transform; and
detecting changes in the second set of transform coefficients with respect to the first set of transform coefficients.
26. The method of claim 25 , wherein the MIMO transform comprises a discrete cosine transform.
27. A transmitter for use in a wireless communication system, comprising:
first apparatus configured to receive a compressed set of transmission channel state information; and
second apparatus configured to use the compressed set of transmission channel state information to generate signal processing information to transmit data from the transmitter to a receiver over a transmission channel;
where:
the compressed set of transmission channel state information comprises information generated at the receiver, and information derived from detected changes in transmission channel state information; and
the compressed set of transmission channel state information comprises only transmission channel state information that meets predetermined selection metrics, the predetermined selection metrics being configured to remove redundant data; and
wherein the compressed set of transmission channel state information is transmitted from the receiver to the transmitter using an index corresponding to channel quality indicator (CQI) information entries in codebooks in the receiver and the transmitter.
28. The transmitter of claim 27 , wherein the predetermined selection metrics are dynamically changed from one channel quality indicator (CQI) reporting instance to another CQI reporting instance.
29. A method for processing signals in a wireless communication system comprising a plurality of transmission channels each comprising on or more channel quality indicator (CQI) parameters, the method comprising:
detecting at least one change in channel state information for a plurality of reporting instances;
ranking the detected at least one change in channel state information; and
generating a compressed set of channel quality indicator (CQI) information, the compressed set configured to omit redundant CQI information, the compressed set of CQI information comprising information useful for transmitting data from a transmitting device to a receiving device over one or more of the plurality of transmission channels;
wherein the compressed set of CQI information comprises only CQI information that meets one or more predetermined selection metrics that are dynamically changed between a first CQI reporting instance and a second CQI reporting instance; and
wherein the generating of the compressed set of CQI information comprises:
ranking CQI values for a first plurality of candidate clusters having a changed CQI information;
selecting therefrom a subset of clusters, the selecting comprising identifying the candidate clusters having the largest change in CQI magnitude; and
using the changed CQI information of the subset of clusters to generate the compressed set of CQI information.
30. The method of claim 29 , wherein changes between a first set of CQI information and a second set of CQI information are detected using at least a CQI transition detector.
31. The method of claim 29 , wherein changes between a first set of CQI information and a second set of CQI information are detected by:
generating first and second sets of transform coefficients based at least in part on a Multiple Input Multiple Output (MIMO) transform; and
detecting changes in the second set of transform coefficients with respect to the first set of transform coefficients.
32. The method of claim 31 , wherein the MIMO transform comprises a discrete cosine transform.