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US 8,804,867 B2Granted
Method and apparatus for using factorized precoding
AssigneeTelefonaktiebolaget L M Ericsson (publ)
InventorsGeorge Jöngren, David Hammarwall
Life of this patent
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Abstract
According to one or more aspects, the teachings herein improve user equipment (UE) Channel State Information (CSI) feedback, by letting the precoder part of a CSI feedback report comprise factorized precoder feedback. In one or more such embodiments, the factorized precoder feedback corresponds to at least two precoder matrices, including a recommended “conversion” precoder matrix and a recommended “tuning” precoder matrix. The recommended conversion precoder matrix restricts the number of channel dimensions considered by the recommended tuning precoder matrix and, in turn, the recommended tuning precoder matrix matches the recommended precoder matrix to an effective channel that is defined in part by said recommended conversion precoder matrix.
Claims38
A method of precoding transmissions from a first device to a second device, said method comprising:
- receiving factorized precoder feedback from the second device indicating at least one of a recommended conversion precoder matrix and a recommended tuning precoder matrix that jointly represent a recommended precoder matrix that is a matrix multiplication of the recommended conversion and tuning precoder matrices, wherein said recommended conversion precoder matrix restricts a number of channel dimensions considered by said recommended tuning precoder matrix and said recommended tuning precoder matrix matches said recommended precoder matrix to an effective channel that is defined in part by said recommended conversion precoder matrix;
- determining a precoding operation based at least in part on evaluating said recommended precoder matrix;
- and
- transmitting a precoded signal to the second device that is precoded according to said precoding operation;
- and
- maintaining one or more codebooks of conversion precoder matrices and tuning precoder matrices, and wherein each conversion precoder matrix has row-column dimensions of NT×k, where NT is the number of rows and equals a number of transmit antenna ports at the first device and k is the number of columns and equals a conversion dimension and wherein said recommended tuning matrix has dimension k×r, where r is a transmission rank used by the first device, and wherein NT, k and r are related as NT≧k≧r to thereby restrict the number of channel dimensions considered by said recommended tuning precoder matrix.
3 more elements
A first device configured for precoding transmissions to a second device, wherein said first device comprises:
- a receiver configured to receive factorized precoder feedback from the second device indicating at least one of a recommended conversion precoder matrix and a recommended tuning precoder matrix that jointly represent a recommended precoder matrix that is a matrix multiplication of the recommended conversion and tuning precoder matrices, wherein said recommended conversion precoder matrix restricts a number of channel dimensions considered by said recommended tuning precoder matrix and said recommended tuning precoder matrix matches said recommended precoder matrix to an effective channel that is defined in part by said recommended conversion precoder matrix;
- and
- a transmitter that includes a precoder circuit and is configured to:
- determine a precoding operation based at least in part on evaluating said recommended precoder matrix;
- and
- transmit a precoded signal to the second device that is precoded according to said precoding operation;
- and
- the first device is configured to maintain one or more codebooks of conversion precoder matrices and tuning precoder matrices, and wherein each conversion precoder matrix has row-column dimensions of NT×k, where NT is the number of rows and equals a number of transmit antenna ports at the first device and k is the number of columns and equals a conversion dimension and wherein said recommended tuning matrix has dimension k×r, where r is a transmission rank used by the first device, and wherein NT, k and r are related as NT≧k≧r to thereby restrict the number of channel dimensions considered by said recommended tuning precoder matrix.
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A method at a second device of indicating a recommended precoder matrix to a first device, said method comprising:
- estimating channel conditions with respect to said first device;
- determining factorized precoder feedback based at least in part on said channel conditions, wherein said factorized precoder feedback indicates at least one of a recommended conversion precoder matrix and a recommended tuning precoder matrix, said recommended conversion and tuning precoder matrices jointly representing a recommended precoder matrix that is a matrix multiplication of the recommended conversion and tuning precoder matrices, and wherein said recommended conversion precoder matrix restricts a number of channel dimensions considered by said recommended tuning precoder matrix and said recommended tuning precoder matrix matches said recommended precoder matrix to an effective channel between said first and second devices that is defined in part by said recommended conversion precoder matrix;
- and
- sending said factorized precoder feedback to said first device to indicate said recommended precoder matrix to said first device;
- and the method further comprises:
- maintaining at said second device one or more codebooks comprising a plurality of conversion precoder matrices, each having row-column dimensions NT×k, where NT is the number of rows and equals a number of transmit antenna ports at the first device and k is the number of columns k and equals a conversion dimension and wherein said recommended tuning matrix has dimension k×r, where r is a transmission rank used by the first device, and wherein NT, k and r are related as NT≧k≧r to thereby restrict the number of channel dimensions considered by said recommended tuning precoder matrix.
3 more elements
A second device configured to indicate a recommended precoder matrix to a first device, said second device comprising:
- a receiver configured to:
- estimate channel conditions with respect to said first device;
- and
- to determine factorized precoder feedback based at least in part on said channel conditions, wherein said factorized precoder feedback indicates at least one of a recommended conversion precoder matrix and a recommended tuning precoder matrix, said recommended conversion and tuning precoder matrices jointly representing a recommended precoder matrix that is a matrix multiplication of the recommended conversion and tuning precoder matrices, and wherein said recommended conversion precoder matrix restricts the number of channel dimensions considered by said recommended tuning precoder matrix and said recommended tuning precoder matrix matches said recommended precoder matrix to an effective channel between said first and second devices that is defined in part by said recommended conversion precoder matrix;
- and
- a transmitter configured to send said factorized precoder feedback to said first device to indicate said recommended precoder matrix to said first device;
- the second device is further configured to maintaining at said second device one or more codebooks comprising a plurality of possible conversion precoder matrices, each having row-column dimensions NT×k, where NT is the number of rows and equals a number of transmit antenna ports at the first device and k is the number of columns and equals a conversion dimension and wherein said recommended tuning matrix has dimension k×r, where r is a transmission rank used by the first device, and wherein NT, k and r are related as NT≧k≧r to thereby restrict the number of channel dimensions considered by said recommended tuning precoder matrix.
4 more elements
Dependencies are inferred from the claim text.