Method for performing channel estimation in wireless communication system and apparatus therefor

1. A method for performing, by a UE, channel estimation in a wireless communication system, the method comprising:

receiving, from an eNB, a control message including reference signal transmission pattern information representing a transmission pattern of a channel estimation reference signal (RS) transmitted through antenna ports;

receiving the reference signal from the eNB based on the received reference signal transmission pattern information;

measuring channel information per antenna port of the eNB based on the received reference signal;

accumulating the measured channel information;

acquiring autocorrelation in the time domain and/or the spatial domain based on the accumulated channel information;

calculating parameters related to 3D channel estimation;

receiving, from the eNB, channel estimation time information for a time when the 3D channel estimation will be performed and virtualization matrix information related to virtualization of a corresponding antenna port;

performing the 3D channel estimation based on the received channel estimation time information; and

feeding back channel state information related to the 3D channel estimation to the eNB,

wherein the reference signal transmission pattern is a form that at least one or more reference signals are transmitted through antenna ports over at least one or more cycles and one cycle relates to one sub-frame,

wherein the antenna ports are determined among total antenna ports of the eNB by the pattern and are different from antenna ports determined from a previous cycle,

wherein the 3D channel estimation is performed for some antenna ports of the total antenna ports,

wherein the some antenna ports are virtualized, the virtualization referring to receiving of the same reference signal through the some antenna ports, and

wherein independent beam coefficients for antenna ports are applied to the virtualization matrix information.

2. The method according to claim 1 , wherein the reference signal transmission pattern is a faun in which L reference signals are transmitted through different antenna ports over K cycles at a specific time.

3. The method according to claim 2 , wherein the control message includes at least one of transmission cycle and offset information related to transmission times of the L reference signals, sequence scrambling information of each reference signal and transmission resource information of each reference signal.

4. The method according to claim 1 , wherein the specific time is a time on a subframe-by-subframe basis, a symbol-by-symbol basis or a radio frame-by-radio frame basis.

5. The method according to claim 1 , wherein the calculated parameters are transmitted along with the channel state information to the eNB.

6. The method according to claim 1 , wherein the 3D channel estimation is performed through Wiener filtering.

7. The method according to claim 1 , wherein the acquiring of autocorrelation in the time domain comprises acquiring a Doppler frequency f d according to mobility of the UE.

8. The method according to claim 7 , wherein the acquiring of the Doppler frequency f d uses the autocorrelation according to the accumulated channel information and autocorrelation acquired by a Bessel function.

9. The method according to claim 1 , wherein the acquiring of autocorrelation in the spatial domain comprises:

measuring channels for a first group of antenna ports and a second group of antenna ports, the first group being a horizontal group of L antenna ports, and the second group being a vertical group of L antenna ports;

accumulating channel information regarding antenna ports, measured per group;

acquiring autocorrelation for antenna ports in the first group and autocorrelation for antenna ports in the second group; and

acquiring an angular spread per group based on the acquired autocorrelation.

10. The method according to claim 1 , wherein the channel estimation time information is received from the eNB through RRC signaling or downlink control information (DCI).

11. The method according to claim 1 , wherein the 3D channel estimation is performed at multiple specific times, and 3D channel information estimated at the multiple specific times is transmitted to the eNB.

12. The method according to claim 1 , wherein the 3D channel estimation is performed only at one of multiple specific times, and 3D channel information estimated at the specific time is transmitted to the eNB at each of the multiple specific times or transmitted to the eNB only at the specific time.

13. The method according to claim 1 , further comprising receiving, from the eNB, information related to the some antenna ports for which the 3D channel estimation is performed.

14. The method according to claim 1 , wherein the some antenna ports are composed of multiple CSI (Channel Status Information)-RS (Reference Signal) port groups, and

further comprising:

receiving, from the eNB, CSI-RS configuration information related to the CSI-RS port groups;

performing 3D channel estimation for the CSI-RS port groups based on the received CSI-RS configuration information;

generating new channel state information by multiplying the estimated CSI-RS port groups by different weight coefficients; and

transmitting the newly generated channel state information to the eNB.

15. A UE for performing channel estimation in a wireless communication system, the UE comprising:

an RF (Radio Frequency) unit configured to transmit and receive radio signals; and

a processor functionally connected to the RF unit and controlling the UE,

wherein the processor is configured to:

receive, from an eNB, a control message including reference signal transmission pattern information representing a transmission pattern of a channel estimation reference signal (RS) transmitted through antenna ports;

receive the reference signal from the eNB based on the received reference signal transmission pattern information;

measure channel information per antenna port of the eNB based on the received reference signal;

accumulate the measured channel information;

acquire autocorrelation in the time domain and/or the spatial domain based on the accumulated channel information;

calculate parameters related to 3D channel estimation;

receive, from the eNB, channel estimation time information for a time when the 3D channel estimation will be performed and virtualization matrix information related to virtualization of a corresponding antenna port;

perform the 3D channel estimation based on the received channel estimation time information; and

feedback channel state information related to the 3D channel estimation to the eNB,

wherein the reference signal transmission pattern is a form that at least one or more reference signals are transmitted through antenna ports over at least one or more cycles and one cycle relates to one sub-frame,

wherein the antenna ports are determined among total antenna ports of the eNB by the pattern and are different from antenna ports determined from a previous cycle,

wherein the 3D channel estimation is performed for some antenna ports of the total antenna ports,

wherein the some antenna ports are virtualized, the virtualization referring to receiving of the same reference signal through the some antenna ports, and

wherein independent beam coefficients for antenna ports are applied to the virtualization matrix information.