Methods and apparatuses for channel estimation and feedback in a three-dimensional multiple input and multiple output system
Embodiments of the present disclosure relate to methods and apparatuses for channel estimation and feedback in a three dimensional multiple input multiple output (3D-MIMO) system. A method may comprise: transmitting a plurality of reference signals for a plurality of columns in an antenna array; receiving indication information on configuration adjustment of a precoding information feedback, wherein the indication information is based on measurement on the plurality of reference signals; and adjusting a configuration of the precoding information feedback based on the indication information so that a multiple vertical precoding information feedback is enabled when it can obtain a performance gain. Especially, the multiple vertical precoding information feedback may represent feeding back a plurality of vertical precoding matrix indicators for the plurality of columns in the antenna array. In embodiments of the present disclosure, there is provided a new solution for channel estimation and feedback in a 3D-MIMO system, and it may achieve a more accurate beamforming and/or a higher order spatial multiplexing, thereby improving the performance of the 3D-MIMO system.
1. A method for channel estimation and feedback in a three dimensional multiple input multiple output system, comprising:
transmitting a plurality of reference signals for a plurality of columns in an antenna array;
receiving indication information on configuration adjustment of a precoding information feedback, wherein the indication information is based on measurement on the plurality of reference signals; and
adjusting a configuration of the precoding information feedback based on the indication information so that a multiple vertical precoding information feedback is enabled when performance gain is obtainable, wherein the multiple vertical precoding information feedback represents feeding back a plurality of vertical precoding matrix indicators for the plurality of columns in the antenna array,
wherein the plurality of reference signals are transmitted for a art of columns in the antenna array.
2. The method according to claim 1 , wherein the part of columns in the antenna array comprises columns in the antenna array which have a space larger than a predetermined value.
3. The method according to claim 2 , wherein the part of columns in the antenna array comprises columns located at both sides of the antenna array.
4. The method according to claim 1 , further comprising:
initializing a configuration of the precoding information feedback;
wherein a precoding information feedback that is initially received is transmitted based on the initialized configuration of the precoding information feedback.
5. The method according to claim 4 , wherein the initialized configuration of the precoding information feedback indicates the UE to
feed back only one vertical precoding matrix indicator for the plurality of columns in the antenna array; or
feed back a plurality of vertical precoding matrix indicators for the plurality of columns in the antenna array.
6. The method according to claim 1 , further comprising:
receiving a precoding information feedback containing a plurality of vertical precoding matrix indicators and a horizontal precoding matrix indicator;
composing a three dimensional precoding matrix based on the plurality of vertical precoding matrix indicators and the horizontal precoding matrix indicator contained in the received precoding information feedback; and
transmitting data after being precoded based on the three dimensional precoding matrix.
7. The method according to claim 6 , wherein, for a column in the antenna array which has no corresponding vertical precoding matrix indicator, a direction of the vertical precoding matrix indicator for the column is determined:
by interpolating precoding matrix indicators of columns near the column; or
as a precoding matrix indicator of a column near the column.
8. A method for channel estimation and feedback in a three dimensional multiple input multiple output system, comprising:
receiving a plurality of reference signals for a plurality of columns in an antenna array;
performing a measurement on the plurality of reference signals; and
transmitting, based on the measurement, indication information on configuration adjustment of a precoding information feedback,
wherein the plurality of reference signals are transmitted for part of columns in the antenna array.
9. The method according to claim 8 , wherein the indication information indicates whether a multiple vertical precoding information feedback can obtain a performance gain, wherein the multiple vertical precoding information feedback represents feeding back a plurality of vertical precoding matrix indicators for the plurality of columns in the antenna array.
10. The method according to claim 8 , further comprising:
receiving an initialized configuration of the precoding information feedback;
initially transmitting the precoding information feedback based on the initialized configuration of the precoding information feedback.
11. The method according to any one of claim 8 , further comprising:
receiving the adjusted configuration of the precoding information feedback; and
transmitting, based on the adjusted configuration of the precoding information feedback, a precoding information feedback containing a plurality of vertical precoding matrix indicators for the plurality of columns in the antenna array.
12. An apparatus for channel estimation and feedback in a three dimensional multiple input multiple output system, comprising:
a signal transmission unit configured to transmit a plurality of reference signals for a plurality of columns in an antenna array;
an information receiving unit configured to receive indication information on configuration adjustment of a precoding information feedback, wherein the indication information is based on measurement on the plurality of reference signals;
a configuration adjustment unit configured to adjust a configuration of the precoding information feedback based on the indication information so that a multiple vertical precoding information feedback is enabled when a performance gain is obtainable, wherein the multiple vertical precoding information feedback represents feeding back a plurality of vertical precoding matrix indicators for the plurality of columns in the antenna array;
a feedback receiving unit configured to receive a precoding information feedback containing a plurality of vertical precoding matrix indicators and a horizontal precoding matrix indicator;
a matrix composing unit configured to compose a three dimensional precoding matrix based on the plurality of vertical precoding matrix indicators and the horizontal precoding matrix indicator contained in the received precoding information feedback; and
a data transmission unit configured to transmit data after being precoded based on the three dimensional precoding matrix.
13. The apparatus according to claim 12 , further comprising:
a configuration initialization unit, configured to initialize a configuration of the precoding information feedback;
wherein a precoding information feedback that is initially received is transmitted based on the initialized configuration of the precoding information feedback.
14. The apparatus according to claim 12 , wherein the matrix composing unit is configured to determine, for a column in the antenna array which has no corresponding vertical precoding matrix indicator, a direction of the vertical precoding matrix indicator for the column:
by interpolating precoding matrix indicators of columns near the column; or
as a precoding matrix indicator of a column near the column.
15. An apparatus for channel estimation and feedback in a three dimensional multiple input multiple output system, comprising:
a signal receiving unit configured to receive a plurality of reference signals for a plurality of columns in an antenna array;
a measurement performing unit configured to perform a measurement on the plurality of reference signals; and
an information transmission unit configured to transmit, based on the measurement, indication information on configuration adjustment of a precoding information feedback,
wherein the indication information transmission unit is configured to:
contain the indication information in an additional bit of channel quality feedback information; or
indicate the indication information by a rank indicator; or
indicate the indication information by whether the same vertical codewords are transmitted for the plurality of columns in the antenna array.
16. The apparatus according to claim 15 , further comprising:
a configuration receiving unit configured to receive an initialized configuration of the precoding information feedback; and
a feedback transmission unit configured to initially transmit the precoding information feedback based on the initialized configuration of the precoding information feedback.
17. The apparatus according to claim 15 , further comprising
a configuration receiving unit configured to receive the adjusted configuration of the precoding information feedback; and
a feedback transmission unit configured to transmit, based on the adjusted configuration of the precoding information feedback, a precoding information feedback containing a plurality of vertical precoding matrix indicators for the plurality of columns in the antenna array.