Method and apparatus for channel estimation in wireless communication system
The present disclosure relates to a pre-5 th -Generation (5G) or 5G communication system to be provided for supporting higher data rates Beyond 4 th -Generation (4G) communication system such as Long Term Evolution (LTE). A method and an apparatus for channel estimation in a wireless communication system are provided. According to various embodiments of the present disclosure, an method of a receiving apparatus in a wireless communication system includes: estimating channel tap values by using a first reference signal; and estimating an effective channel regarding a second reference signal, based on channel tap indexes corresponding to values greater than or equal to a threshold from among the channel tap values. According to various embodiments of the present disclosure, the receiving apparatus can more exactly estimate an effective channel, and can achieve a lower BLER even in a high SNR region.
1. A method for operating a reception device in a wireless communication system, the method comprising:
determining a channel impulse response (CIR) for channel tap indexes based on a cell-specific reference signal (CRS) or a sounding reference signal (SRS);
identifying significant channel tap indexes of channel tap values among the channel tap indexes, wherein the channel tap values are greater than a threshold among a plurality of channel tap values of the CIR;
determining an effective CIR for the significant channel tap indexes based on a demodulation reference signal (DMRS); and
obtaining an effective channel frequency response (CFR) by applying a Fourier transform to the effective CIR.
2. The method of claim 1 , wherein determining the effective CIR comprises determining a second system matrix formed of column vectors corresponding to the significant channel tap indexes in a first system matrix related to the DMRS; and
wherein obtaining the effective CFR comprises determining the effective CFR based on the second system matrix.
3. The method of claim 1 , wherein a power delay profile (PDP) of the channel tap values is uniform with respect to the significant channel tap indexes.
4. The method of claim 1 , wherein a power delay profile (PDP) of the channel tap values exponentially decays with respect to the significant channel tap indexes as a channel tap index increases.
5. The method of claim 1 , further comprising:
filtering the SRS or the CRS based on a matched filter to obtain a filtered signal;
determining at least one block comprising entries whose power sum is greater than or equal to a threshold power in the filtered signal;
determining a second system matrix formed of column vectors corresponding to the at least one block in a first system matrix related to the SRS or CRS;
performing zero-forcing with respect to the SRS or CRS based on the second system matrix; and
determining values greater than or equal to a threshold from among the plurality of channel tap values based on a result of the zero-forcing as the channel tap values.
6. The method of claim 1 , wherein determining the effective CIR comprises:
determining an average power of the channel tap values corresponding to the significant channel tap indexes; and
determining the effective CIR based on the average power.
7. The method of claim 1 , wherein:
the CRS or the SRS is transmitted from a plurality of transmission antennas of a transmission device, and
the DMRS is transmitted from the plurality of transmission antennas.
8. The method of claim 1 , wherein a beamforming applied to the DMRS is a same as a beamforming applied to data multiplexed with the DMRS.
9. A reception device in a wireless communication system, comprising:
a transceiver configured to receive a cell-specific reference signal (CRS) or a sounding reference signal (SRS), and a demodulation reference signal (DMRS); and
at least one processor configured to:
determine a channel impulse response (CIR) for channel tap indexes based on the CRS or SRS,
identify significant channel tap indexes of channel tap values among the channel tap indexes, wherein the channel tap values are greater than a threshold among a plurality of channel tap values of the CIR;
determine an effective CIR for the significant channel tap indexes based on the DMRS; and
obtain an effective channel frequency response (CFR) by applying a Fourier transform to the effective CIR.
10. The reception device of claim 9 , wherein the at least one processor is configured to:
determine a second system matrix formed of column vectors corresponding to the significant channel tap indexes in a first system matrix related to the DMRS, and
determine the effective CFR based on the second system matrix.
11. The reception device of claim 9 , wherein a power delay profile (PDP) of the channel tap values is uniform with respect to the significant channel tap indexes.
12. The reception device of claim 9 , wherein a power delay profile (PDP) of the channel tap values exponentially decays with respect to the significant channel tap indexes as a channel tap index increases.
13. The reception device of claim 9 , wherein the at least one processor is configured to:
filter the SRS or the CRS based on a matched filter to obtain a filtered signal;
determine at least one block comprising entries whose power sum is greater than or equal to a threshold power in the filtered signal;
determine a second system matrix formed of column vectors corresponding to the at least one block in a first system matrix related to the SRS or CRS;
perform zero-forcing with respect to the SRS or CRS based on the second system matrix; and
determine values greater than or equal to a threshold from among the plurality of channel tap values based on a result of the zero-forcing as the channel tap values.
14. The reception device of claim 9 , wherein the at least one processor is configured to:
determine an average power of the channel tap values corresponding to the significant channel tap indexes; and
determine the effective CIR based on the average power.
15. The reception device of claim 9 , wherein:
the CRS or the SRS is transmitted from a plurality of transmission antennas of a transmission device, and
the DMRS is transmitted from the plurality of transmission antennas.
16. The reception device of claim 9 , wherein beamforming applied to the DMRS is a same as beamforming applied to data multiplexed with the DMRS.
17. The method of claim 1 , wherein the determining of the effective CIR for the significant channel tap indexes comprises:
determining an average power of the channel tap values based on a sum of powers for the plurality of channel tap values of the CIR and a number of the significant channel tap indexes; and
determining the effective CIR for the significant channel tap indexes based on the average power of the channel tap values.
18. The reception device of claim 9 , wherein the at least one processor is further configured to:
determine an average power of the channel tap values based on a sum of powers for the plurality of channel tap values of the CIR and a number of the significant channel tap indexes; and
determine the effective CIR for the significant channel tap indexes based on the average power of the channel tap values.