Method and apparatus for constructing codebook, and method, apparatus and system for precoding

1. A method for constructing a codebook, comprising:

receiving grouping information on a plurality of transmit antennas of a base station;

obtaining a channel model for a channel between a mobile terminal and the base station; and

determining an optimal precoding matrix corresponding to each antenna group according to the grouping information and the channel model, so as to construct a codebook used for precoding, wherein the determining comprises:

applying the grouping information and the channel model to predetermined criteria, so as to determine an optimal precoding matrix that satisfies the predetermined criteria;

calculating, according to the grouping information and the channel model, a precoding matrix that makes a Chordal distance, a projection two-norm distance or a Fubini-Study distance be minimum; and

determining the precoding matrix that makes the distance be minimum as the optimal precoding matrix.

2. An apparatus for constructing a codebook, comprising:

a receiver for receiving grouping information on a plurality of transmit antennas of a base station;

a channel model obtaining module for obtaining a channel model for a channel between a mobile terminal and the base station; and

a precoding matrix determining module for determining an optimal precoding matrix corresponding to each antenna group according to the grouping information and the channel model, so as to construct a codebook used for precoding, wherein the determining comprises:

applying the grouping information and the channel model to predetermined criteria, so as to determine an optimal precoding matrix that satisfies the predetermined criteria;

calculating, according to the grouping information and the channel model, a precoding matrix that makes a Chordal distance, a projection two-norm distance or a Fubini-Study distance be minimum; and

determining the precoding matrix that makes the distance be minimum as the optimal precoding matrix.

3. A method for selecting a precoding matrix, comprising:

receiving grouping information on a plurality of transmit antennas of a base station;

estimating a channel from the base station to obtain a channel model;

selecting from a codebook an optimal precoding matrix corresponding to each antenna group, based on the grouping information and the channel model, wherein the selecting comprises:

applying the grouping information and the channel model to predetermined criteria, so as to determine a precoding matrix that satisfies the predetermined criteria;

calculating, according to the grouping information and the channel model, a precoding matrix that makes a Chordal distance, a projection two-norm distance or a Fubini-Study distance be minimum; and

determining the precoding matrix that makes the distance be minimum as the optimal precoding matrix; and

sending an index of each optimal precoding matrix to the base station so that the base station performs concatenated precoding.

4. The method according to claim 3 , wherein selecting the optimal precoding matrix further comprises:

retrieving in the codebook a precoding matrix matching the precoding matrix that satisfies the predetermined criteria, as the optimal precoding matrix.

5. An apparatus for selecting a precoding matrix, comprising:

a receiver for receiving grouping information on a plurality of transmit antennas of a base station;

a channel model obtaining module for estimating a channel from the base station to obtain a channel model;

a precoding matrix selecting module for selecting from a codebook an optimal precoding matrix corresponding to each antenna group, based on the grouping information and the channel model, wherein selecting the optimal precoding matrix further comprises:

calculating, according to the grouping information and the channel model, a precoding matrix that makes a Chordal distance, a projection two-norm distance or a Fubini-Study distance be minimum; and

determining the precoding matrix that makes the distance be minimum as the optimal precoding matrix; and

a transmitter for sending an index of each optimal precoding matrix to the base station so that the base station performs concatenated precoding.

6. The apparatus according to claim 5 , wherein the precoding matrix selecting module is configured to:

apply the grouping information and the channel model to predetermined criteria, so as to determine a precoding matrix that satisfies the predetermined criteria; and

retrieve in the codebook a precoding matrix matching the precoding matrix that satisfies the predetermined criteria, as the optimal precoding matrix.

7. A communication system, comprising:

an apparatus according to claim 5 ; and

an apparatus comprising a constructing module for constructing a concatenated precoding matrix according to indices of a plurality of optimal precoding matrixes received from a mobile terminal, a precoding module for precoding data using the constructed concatenated precoding matrix, and a transmitter for sending the precoded data to the mobile terminal.

8. A method for precoding, comprising:

constructing a concatenated precoding matrix according to indices of a plurality of optimal precoding matrixes received from a mobile terminal, wherein the constructing comprises:

retrieving in a codebook precoding matrixes that correspond to the indices of the plurality of optimal precoding matrixes; and

combining the retrieved precoding matrixes into the concatenated precoding matrix;

precoding data using the constructed concatenated precoding matrix; and

sending the precoded data to the mobile terminal.

9. The method according to claim 8 , wherein the combining the retrieved precoding matrixes into the concatenated precoding matrix further comprises:

weighting the retrieved precoding matrixes, respectively; and

combining the weighted precoding matrixes into the concatenated precoding matrix.

10. The method according to claim 8 , wherein the combining the retrieved precoding matrixes into the concatenated precoding matrix further comprises:

weighting the concatenated precoding matrix so as to achieve normalization.

11. An apparatus for precoding, comprising:

a constructing module for constructing a concatenated precoding matrix according to indices of a plurality of optimal precoding matrixes received from a mobile terminal, wherein the constructing module is configured to:

retrieve in a codebook precoding matrixes that correspond to the indices of the plurality of optimal precoding matrixes; and

combine the retrieved precoding matrixes into the concatenated precoding matrix;

a precoding module for precoding data using the constructed concatenated precoding matrix; and

a transmitter for sending the precoded data to the mobile terminal.