Linear precoding for time division duplex system
First Claim
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1. A method that facilitates generating feedback related to a forward link channel for linear precoding, comprising:
- estimating a forward link channel to generate a matrix;
modifying matrices from a codebook to obtain a set of tailored matrices corresponding to a modified codebook, wherein the matrices from the codebook are modified at least in part based upon implicit channel related information provided via a reverse link channel;
quantizing a portion of the matrix to yield explicit feedback, wherein quantizing comprises comparing the matrix with the set of tailored matrices from the modified codebook to identify a closest tailored matrix; and
transmitting quantized data over a reverse link channel that provides implicit feedback corresponding to a remainder of the matrix, wherein the implicit feedback is not identical to the explicit feedback, and wherein the implicit feedback provides information about a part of the matrix other than the quantized portion.
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Abstract
Systems and methodologies are described that facilitate generating and/or utilizing explicit and implicit feedback related to a forward link channel for linear precoding in a time division duplex (TDD) multiple-input multiple-output (MIMO) system. Implicit feedback may be provided by estimating a reverse link channel, which may be substantially similar to at least a portion of the forward link channel (e.g., based upon reciprocity). Moreover, explicit feedback may be yielded by quantizing at least part of an estimate of the forward link channel (e.g., utilizing vector and/or scalar quantization).
66 Citations
38 Claims
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1. A method that facilitates generating feedback related to a forward link channel for linear precoding, comprising:
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estimating a forward link channel to generate a matrix; modifying matrices from a codebook to obtain a set of tailored matrices corresponding to a modified codebook, wherein the matrices from the codebook are modified at least in part based upon implicit channel related information provided via a reverse link channel; quantizing a portion of the matrix to yield explicit feedback, wherein quantizing comprises comparing the matrix with the set of tailored matrices from the modified codebook to identify a closest tailored matrix; and transmitting quantized data over a reverse link channel that provides implicit feedback corresponding to a remainder of the matrix, wherein the implicit feedback is not identical to the explicit feedback, and wherein the implicit feedback provides information about a part of the matrix other than the quantized portion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A wireless communications apparatus, comprising:
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a memory that retains a codebook and an estimated matrix related to a forward link channel; and a processor, coupled to the memory, configured to modify matrices from the codebook to obtain a set of tailored matrices corresponding to a modified codebook, wherein the matrices from the codebook are modified based at least in part upon one or more links employed for communicating via a reverse link channel, wherein the processor is also configured to compare a portion of the estimated matrix to the set of tailored matrices in the modified codebook to select a closest tailored matrix, and transmit an index associated with the selected, closest tailored matrix over the reverse link channel. - View Dependent Claims (13, 14, 15)
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16. A wireless communications apparatus for generating and transferring implicit and explicit feedback related to a forward link channel, comprising:
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means for estimating a forward link channel to yield a matrix; means for modifying matrices from a codebook to obtain a set of tailored matrices corresponding to a modified codebook, wherein the matrices from the codebook are modified at least in part based upon implicit channel related information provided via a reverse link channel; means for quantizing a subset of the matrix, wherein quantizing comprises comparing the matrix with the set of tailored matrices from the modified codebook to identify a closest tailored matrix; and means for transmitting quantized data over a reverse link channel that provides implicit feedback related to a remainder of the matrix, wherein the implicit feedback is not identical to the explicit feedback, and wherein the implicit feedback provides information about a part of the matrix other than the quantized portion. - View Dependent Claims (17, 18)
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19. A non-transitory machine-readable medium having stored thereon machine-executable instructions for:
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estimating a forward link channel; generating a unitary matrix associated with the forward link channel; modifying matrices from a codebook to obtain a set of tailored matrices corresponding to a modified codebook, wherein the matrices from the codebook are modified at least in part based upon implicit channel related information provided via a reverse link channel; quantizing a portion of the unitary matrix that corresponds to one or more antennas of a mobile device that are inactive for reverse link channel communication, wherein quantizing comprises comparing the matrix with the set of tailored matrices from the modified codebook to identify a closest tailored matrix; and transmitting the quantized data over the reverse link channel, wherein the reverse link channel provides implicit feedback corresponding to one or more links associated with one or more active antennas of the mobile device, wherein the implicit feedback is not identical to the explicit feedback, and wherein the implicit feedback provides information about a part of the matrix other than the quantized portion. - View Dependent Claims (20, 21)
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22. In a wireless communication system, an apparatus comprising:
a processor configured to; generate a matrix related to an estimated forward link channel; modify matrices from a codebook to obtain a set of tailored matrices corresponding to a modified codebook, wherein the matrices from the codebook are modified at least in part based upon implicit channel related information provided via a reverse link channel; quantize a portion of the matrix to yield explicit feedback related to part of the estimated forward link channel, wherein quantizing comprises comparing the matrix with the set of tailored matrices from the modified codebook to identify a closest tailored matrix; and transmit quantized data over a reverse link channel, wherein the reverse link channel provides implicit feedback related to a remainder of the estimated forward link channel, wherein the implicit feedback is not identical to the explicit feedback, and wherein the implicit feedback provides information about a part of the matrix other than the quantized portion.
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23. A method that facilitates utilizing implicit and explicit feedback related to a forward link channel for linear precoding, comprising:
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estimating a reverse link channel to obtain implicit feedback related to a portion of a forward link channel; modifying matrices from a codebook to obtain a set of tailored matrices corresponding to a modified codebook, wherein the matrices from the codebook are modified at least in part based upon implicit channel related information provided via a reverse link channel; evaluating explicit feedback related to a remainder of the forward link channel received via the reverse link channel, wherein evaluating the explicit feedback comprises receiving an index from a mobile device that modified a substantially similar codebook in a substantially similar manner and identifying an adapted matrix from the modified codebook based upon the received index, and wherein the implicit feedback is not identical to the explicit feedback; combining the explicit feedback and the implicit feedback; and modifying communication over the forward link channel utilizing the combined feedback. - View Dependent Claims (24, 25, 26, 27, 28)
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29. A wireless communications apparatus, comprising:
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a memory that retains a codebook and an index associated with the codebook received over a reverse link channel; and a processor, coupled to the memory, configured to modify matrices from the codebook to obtain a set of tailored matrices corresponding to a modified codebook, wherein the matrices from the codebook are modified based at least in part upon one or more links utilized for communication via the reverse link channel, wherein the processor is further configured to determine an adapted matrix from the modified codebook related to the index, and combine explicit feedback associated with the adapted matrix with implicit feedback estimated from the reverse link channel. - View Dependent Claims (30, 31, 32)
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33. A wireless communications apparatus for utilizing implicit and explicit feedback related to a forward link channel to modify subsequent transmission over the forward link channel, comprising:
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means for obtaining implicit feedback received via a reverse link channel; means for modifying matrices from a codebook to obtain a set of tailored matrices corresponding to a modified codebook, wherein the matrices from the codebook are modified at least in part based upon implicit channel related information provided via a reverse link channel; means for analyzing explicit feedback received via the reverse link channel, wherein analyzing the explicit feedback comprises receiving an index from a mobile device that modified a substantially similar codebook in a substantially similar manner and identifying an adapted matrix from the modified codebook based upon the received index, and wherein the implicit feedback is not identical to the explicit feedback; and means for modifying communication over a forward link channel based upon a combination of the implicit feedback and the explicit feedback. - View Dependent Claims (34, 35)
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36. A non-transitory machine-readable medium having stored thereon machine-executable instructions for:
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estimating a reverse link channel to obtain implicit feedback corresponding to a portion of a forward link channel; modifying matrices from a codebook to obtain a set of tailored matrices corresponding to a modified codebook, wherein the matrices from the codebook are modified at least in part based upon implicit channel related information provided via a reverse link channel; identifying an adapted matrix from the modified codebook; analyzing explicit feedback received via the reverse link channel, wherein the explicit feedback corresponds to the remainder of the forward link channel, wherein analyzing the explicit feedback comprises receiving an index from a mobile device that modified a substantially similar codebook in a substantially similar manner and identifying an adapted matrix from the modified codebook based upon the received index, and wherein the implicit feedback is not identical to the explicit feedback; and employing a combination of the implicit feedback and the explicit feedback to modify communication over the forward link channel. - View Dependent Claims (37)
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38. In a wireless communication system, an apparatus comprising:
a processor configured to; estimate a reverse link channel to determine implicit feedback related to a portion of a forward link channel; modify matrices from a codebook to obtain a set of tailored matrices corresponding to a modified codebook, wherein the matrices from the codebook are modified at least in part based upon implicit channel related information provided via a reverse link channel; evaluate explicit feedback related to a remainder of the forward link channel received via the reverse link channel, wherein evaluating the explicit feedback comprises receiving an index from a mobile device that modified a substantially similar codebook in a substantially similar manner and identifying an adapted matrix from the modified codebook based upon the received index, and wherein the implicit feedback is not identical to the explicit feedback; and combine the implicit feedback and the explicit feedback.
Specification