Unified feedback frame for supporting a plurality of feedback modes and a multiple-input multiple-output (MIMO) communication system using the unified feedback frame
Provided is a multiple-input multiple-output (MIMO) communication system that may provide a plurality of feedback modes. A receiver may feed back, to a transmitter, a base codeword indicator indicating one of base codewords included in the base codebook, a differential codeword indicator indicating one of differential codewords included in the differential codebook, and/or a correlation codeword indicator indicating one of correlation codewords included in the correlation codebook. The transmitter may generate a precoding matrix using at least one of the base codeword indicator, the differential codeword indicator, and the correlation codeword indicator.
1. A communication method of a transmitter in a multiple-input multiple-output (MIMO) communication system, the communication method comprising:
accessing a base codebook comprising base codewords and an additional codebook comprising additional codewords;
receiving, from a receiver, a base codeword indicator that indicates one of the base codewords included in the base codebook recommended for a wideband and an additional codeword indicator that indicates one of the additional codewords included in the additional codebook recommended for a sub-band from among a plurality of sub-bands included in the wideband; and
generating a precoding matrix for the receiver in the sub-band using the base codeword indicator recommended for the wideband and the additional codeword indicator recommended for the sub-band.
2. The communication method of claim 1 , wherein the additional codebook comprises a differential codebook that comprises differential codewords.
3. The communication method of claim 2 , wherein the additional codebook further comprises a correlation codebook that comprises correlation codewords.
4. The communication method of claim 3 , wherein:
the receiving comprises receiving the base codeword indicator that indicates one of the base codewords included in the base codebook, a differential codeword indicator that indicates one of the differential codewords included in the differential codebook, and a correlation codeword indicator that indicates one of the correlation codewords included in the correlation codebook, and
the generating comprises generating the precoding matrix for the receiver using the base codeword indicator, the differential codeword indicator, and the correlation codeword indicator.
5. The communication method of claim 3 , wherein:
the differential codeword indicator indicates a difference in a time domain with respect to the base codeword indicator or a difference in a frequency domain with respect to the base codeword indicator, and
the correlation codeword indicator indicates a correlation of a channel formed between the transmitter and the receiver.
6. The communication method of claim 3 , wherein, when the differential codeword indicator is fixed as a predetermined matrix and the correlation codeword indicator is fixed as another predetermined matrix, the base codeword indicator indicates one of the base codewords in a wideband comprising a plurality of sub-bands or indicates one of the base codewords in a corresponding sub-band among the plurality of sub-bands.
7. The communication method of claim 3 , wherein:
when the correlation codeword indicator is fixed as a predetermined matrix, the base codeword indicator indicates one of the base codewords in a wideband comprising a plurality of sub-bands or in a corresponding sub-band from among the plurality of sub-bands, and the differential codeword indicator indicates one of the differential codewords in the corresponding sub-band among the plurality of sub-bands,
the generating comprises refining the base codeword indicator using the differential codeword indicator to generate the precoding matrix for the receiver.
8. The communication method of claim 7 , wherein the receiving comprises sequentially receiving one or more differential codeword indicators with respect to a single base codeword indicator.
9. The communication method of claim 2 , wherein the generating comprises:
refining the base codeword indicator using the differential codeword indicator; and
performing an inner product between the base codeword indicator and the refined base codeword indicator to generate the precoding matrix for the receiver.
10. The communication method of claim 2 , wherein:
when the differential codeword indicator is fixed as a predetermined matrix and the base codeword indicator indicates one of the base codewords in a wideband comprising a plurality of sub-bands or in a corresponding sub-band among the plurality of sub-bands,
the generating comprises adaptively adjusting the precoding matrix for the receiver using the correlation codeword indicator.
11. The communication method of claim 2 , wherein:
the base codeword indicator indicates one of the base codewords in a wideband comprising a plurality of sub-bands or in a corresponding sub-band from among the plurality of sub-bands, and the differential codeword indicator indicates one of the differential codewords in the corresponding sub-band from among the plurality of sub-bands,
the receiving comprises receiving the base codeword indicator and the differential codeword indicator in the same time interval, and
the generating comprises refining the base codeword indicator in a frequency domain using the differential codeword indicator to generate the precoding matrix for the receiver.
12. The communication method of claim 2 , wherein:
the base codeword indicator indicates one of the base codewords in a wideband that comprises a plurality of sub-bands, and the differential codeword indicator indicates one of the differential codewords in the corresponding sub-band from among the plurality of sub-bands,
the receiving comprises receiving each of the base codeword indicator and the differential codeword indicator in a different time interval, and
the generating comprises refining the base codeword indicator in both a time domain and a frequency domain using the differential codeword indicator to generate the precoding matrix for the receiver.
13. The communication method of claim 2 , wherein:
the base codeword indicator indicates one of the base codewords in a corresponding sub-band from among a plurality of sub-bands, and the differential codeword indicator indicates one of the differential codewords in the corresponding sub-band from among the plurality of sub-bands,
the receiving comprises receiving the base codeword indicator and the differential codeword indicator in the same time interval, and
the generating comprises refining the base codeword indicator in a frequency domain using the differential codeword indicator to generate the precoding matrix for the receiver.
14. The communication method of claim 2 , wherein:
the base codeword indicator indicates one of the base codewords in a corresponding sub-band from among a plurality of sub-bands, and the differential codeword indicator indicates one of the differential codewords in the corresponding sub-band from among the plurality of sub-bands,
the receiving comprises receiving each of the base codeword indicator and the differential codeword indicator at different time intervals, and
the generating comprises refining the base codeword indicator in a time domain using the differential codeword indicator to generate the precoding matrix for the receiver.
15. A communication method of a receiver in a MIMO communication system, the communication method comprising:
estimating a channel formed between a transmitter and the receiver;
accessing a base codebook comprising base codewords and an additional codebook comprising additional codewords;
generating, based on the estimated channel, a base codeword indicator that indicates one of the base codewords included in the base codebook recommended for a wideband and an additional codeword indicator that indicates one of the additional codewords included in the additional codeword recommended for a sub-band from among a plurality of sub-bands included in the wideband; and
transmitting the base codeword indicator recommended for the wideband and the additional codeword indicator recommended for the sub-band to the transmitter.
16. The communication method of claim 15 , wherein the additional codebook comprises a differential codebook that comprises differential codewords.
17. The communication method of claim 16 , wherein the additional codebook further comprises a correlation codebook that comprises correlation codewords.
18. The communication method of claim 17 , wherein the generating comprises generating the base codeword indicator that indicates one of the base codewords included in the base codebook, a differential codeword indicator that indicates one of the differential codewords included in the differential codebook, and a correlation codeword indicator that indicates one of the correlation codewords included in the correlation codebook.
19. The communication method of claim 17 , wherein at least one of the differential codeword indicator and the correlation codeword indicator is fixed as a predetermined matrix.
20. The communication method of claim 16 , wherein the base codeword indicator indicates one of the base codewords in a wideband that comprises a plurality of sub-bands or in a corresponding sub-band from among the plurality of sub-bands, and the differential codeword indicator indicates one of the differential codewords in the corresponding sub-band from among the plurality of sub-bands.
21. A transmitter supporting multiple feedback modes in a multiple-input multiple-output (MIMO) network, the transmitter comprising:
a memory configured to store at least a first mode codebook and a second mode codebook;
a receiving unit configured to receive, from a receiver, a first codeword indicator that indicates a first codeword from among a plurality of codewords included in the first mode codebook recommended for a wideband, and a second codeword indicator that indicates a second codeword out of a plurality of codewords included in the second mode codebook recommended for a sub-band from among a plurality of sub-bands included in the wideband;
a precoding matrix generator configured to generate a precoding matrix for the receiver in the sub-band based on the first codeword indicator recommended for the wideband and the second codeword indicator recommended for the sub-band;
a precoder configured to precode at least one data stream using the generated precoding matrix; and
a transmitting unit configured to transmit the precoded at least one data stream to the receiver.
22. The transmitter of claim 21 , wherein the received first codeword indicator indicates a base codeword from a base codebook recommended in the wideband that comprises the plurality of sub-bands, and the received second codeword indicator indicates a differential codeword from a differential codebook recommended in the sub-band out of the plurality of sub-bands in the wideband, and
the precoding matrix generator generates the precoding matrix by refining the received base codeword using the received differential codeword.
23. A receiver supporting multiple feedback modes in a multiple-input multiple-output (MIMO) network, the receiver comprising:
a channel estimator configured to estimate a channel formed between the receiver and a transmitter;
a memory configured to store at least a first mode codebook and a second mode codebook; and
an indicator generator configured to generate a first codeword indicator that indicates a first codeword out of a plurality of codewords included in the first mode codebook recommended for a wideband, and configured to generate a second codeword indicator that indicates a second codeword out of a plurality of codewords included in the second mode codebook recommended for a sub-band from among a plurality of sub-bands included in the wideband; and
a transmitting unit configured to transmit the first codeword indicator recommended for the wideband and the second codeword indicator recommended for the sub-band to the transmitter.
24. The receiver of claim 23 , wherein the first codeword indicator indicates a base codeword from a base codebook recommended in the wideband that comprises the plurality of sub-bands, and the second codeword indicator indicates a differential codeword from a differential codebook recommended in the sub-band out of the plurality of sub-bands in the wideband.
25. The receiver of claim 23 , wherein the transmitting unit transmits the first codeword indicator at a first time interval and transmits the second codeword indicator at a second time interval that is different from the first time interval.
26. The receiver of claim 23 , wherein the transmitting unit transmits the first codeword indicator and the second codeword indicator at the same time interval.