Wireless communication apparatus for adaptive beamforming and method of operation thereof
A method of operating a wireless communication apparatus, the method comprising: estimating a first channel using a sounding packet received from a base station to obtain an estimated first channel, the sounding packet including a plurality of first streams, generating a diagonal matrix and a beam steering matrix by performing singular value decomposition (SVD) on the estimated first channel, generating state information of a plurality of second channels respectively corresponding to a plurality of second streams generated by applying the beam steering matrix to the plurality of first streams using the diagonal matrix, and transmitting beamforming feedback based on the state information to the base station.
1. A method of operating a wireless communication apparatus, the method comprising:
estimating a first channel using a sounding packet received from a base station to obtain an estimated first channel, the sounding packet including a plurality of first streams;
generating a diagonal matrix and a beam steering matrix by performing singular value decomposition (SVD) on the estimated first channel;
generating state information of a plurality of second channels respectively corresponding to a plurality of second streams generated by applying the beam steering matrix to the plurality of first streams using the diagonal matrix; and
transmitting beamforming feedback based on the state information to the base station.
2. The method of claim 1 , wherein the generating state information further comprises:
determining a plurality of signal to noise ratios (SNRs) by obtaining a plurality of singular values corresponding to the plurality of second channels from the diagonal matrix, each of the plurality of second channels corresponding to a respective SNR among the plurality of SNRs, and each of the plurality of singular values corresponding to a respective second channel among the plurality of second channels.
3. The method of claim 2 , wherein the determining determines a plurality of SNRs such that a subset of the plurality of SNRs are referenced to determine a number of beamforming ranks.
4. The method of claim 3 , wherein the determining determines a plurality of SNRs such that a lowest target SNR among the plurality of SNRs is referenced to determine the number of beamforming ranks.
5. The method of claim 3 , wherein the determining a plurality of SNRs such that a plurality of target SNRs among the plurality of SNRs equal to or less than a reference value are referenced to determine the number of beamforming ranks.
6. The method of claim 2 , further comprising:
generating a rank indicator indicating a number of appropriate ranks for wireless communication based on the state information.
7. The method of claim 6 , the generating a rank indicator further comprises:
comparing a lowest target SNR among the plurality of SNRs with a reference value; and
determining the number of appropriate ranks based on a number of ranks corresponding to the lowest target SNR based on a result of the comparing.
8. The method of claim 6 , wherein the generating a rank indicator further comprises:
calculating an average value of a plurality of target SNRs among the plurality of SNRs that are less than a first reference value;
comparing the average value with a second reference value; and
determining the number of appropriate ranks based on a number of ranks corresponding to each of the plurality of target SNRs and a result of the comparing.
9. The method of claim 1 , wherein
the state information includes a plurality of channel states, each respective channel state among the plurality of channel states corresponding to one of the plurality of second channels; and
the method further comprises generating a rank indicator based on a particular second channel among the plurality of second channels corresponding to a particular channel state among the plurality of channel states less than a reference value.
10. The method of claim 9 ,
wherein the beamforming feedback includes the rank indicator.
11. The method of claim 9 , further comprising:
determining the reference value based on a multiple input multiple output (MIMO) scheme between the base station and the wireless communication apparatus.
12. The method of claim 1 ,
wherein each of the plurality of first streams is modulated and encoded using a same modulation and coding scheme.
13. A method of operating a wireless communication apparatus, the method comprising:
generating a diagonal matrix and a beam steering matrix by performing singular value decomposition on a channel matrix corresponding to a first channel between a base station and the wireless communication apparatus, the diagonal matrix including a plurality of singular values;
determining a plurality of signal to noise ratios (SNRs) corresponding to a plurality of second channels over which are received a plurality of beam steering streams to which the beam steering matrix is applied using the diagonal matrix; and
providing beamforming feedback including the plurality of SNRs and the beam steering matrix to the base station.
14. The method of claim 13 , further comprising:
receiving a sounding packet including a plurality of sounding streams from the base station; and
generating the channel matrix by estimating the first channel using a reference signal included in the sounding packet.
15. The method of claim 13 , wherein the determining a plurality of SNRs further comprises:
determining an N th SNR corresponding to an Nth channel among the plurality of second channels based on a plurality of singular values corresponding to a plurality of sub carriers included in the Nth channel, N being an integer of 1 or more.
16. The method of claim 13 , further comprising:
generating a rank indicator indicating a number of appropriate ranks of the wireless communication apparatus based on an SNR of a target channel among the plurality of second channels corresponding to a largest number of ranks and a reference value.
17. The method of claim 16 , the generating a rank indicator comprises:
determining the number of appropriate ranks to be one rank lower than a number of ranks corresponding to the target channel in response to the SNR of the target channel being less than the reference value.
18. The method of claim 16 ,
wherein the reference value is based on a number of antennas of the base station and a number of antennas of the wireless communication apparatus used for multiple input multiple output (MIMO).
19. The method of claim 13 , further comprising:
generating a rank indicator indicating a number of appropriate ranks of the wireless communication apparatus based on a subset of the plurality of SNRs associated with a plurality of target channels among the plurality of second channels corresponding to a number of ranks greater than a reference number.
20. A wireless communication apparatus comprising:
a plurality of antennas configured to support beamforming; and
processing circuitry configured to,
estimate a first channel using a sounding packet received from a base station, the sounding packet including a plurality of first streams to obtain an estimated first channel,
perform singular value decomposition on the estimated first channel to generate a diagonal matrix and a beam steering matrix,
generate state information of at least one target channel among a plurality of second channels corresponding to a plurality of second streams generated by applying the beam steering matrix to the plurality of first streams such that the state information is usable for determining a number of beamforming ranks, and
generate beamforming feedback based on the state information for transmission to the base station.