METHOD AND APPARATUS FOR TRANSMITTING/RECEIVING CSI-RS IN MASSIVE MIMO SYSTEM OPERATING IN FDD MODE

• US 20130163544A1
• Filed: 12/27/2012
• Published: 06/27/2013
• Est. Priority Date: 12/27/2011
• Status: Active Grant

• Current Assignee: Industry Academic Cooperation Foundation, Samsung Electronics Co. Ltd. (Samsung Group)
• Original Assignee: Korea National University Of Transportation Industry-Academic Cooperation Foundation, Samsung Electronics Co. Ltd. (Samsung Group)
• Inventors: LEE, Hyojin, MUN, Cheol, KIM, Kiil, KIM, Younsun, LEE, Juho, CHO, Joonyoung
• Granted Patent: US 9,635,642 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04B 7/0695 using beam selection
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0091 Signaling for the administration of the divided path
• CPC Class Codes: H04L 5/143 for modulated signals H04L5/1469 takes precedence
• CPC Class Codes: H04W 72/04 Wireless resource allocation

Abstract

Methods and apparatus are provided for beamforming and information feedback are provided. Signals for beams to be transmitted through corresponding antenna ports, are generated. The beams are formed by precoding the signals with beamforming vectors. The beams are sorted into a number of resource reuse groups based on a resource that is to be shared. The beams are transmitted, using resources allocated per group, to a receiver. Feedback information is generated on at least one antenna port, based on the received beams. The feedback information is transmitted to the transmitter. A beam is selected having a greatest gain for a transmitter using the feedback information. A transmission resource is allocated for the selected beam.

Claims

1. A beamforming method of a transmitter using a plurality of antenna ports in a wireless communication system, the beamforming method comprising the steps of:

generating signals for beams to be transmitted through corresponding antenna ports;

forming the beams by precoding the signals with beamforming vectors;

sorting the beams into a number of resource reuse groups based on a resource that is to be shared;

transmitting the beams, using resources allocated per group, to a receiver;

selecting a beam having a greatest gain for a transmitter using feedback information on at least one of the antenna ports, which is transmitted by the receiver; and

allocating a transmission resource for the selected beam.

2. The beamforming method of claim 1, wherein selecting the beam comprises:

receiving an index of one of the resource reuse groups having a greatest gain in association with a downlink channel and a beamforming vector, from the receiver;

estimating an uplink spatial correlation matrix using an uplink Sounding Reference Signal (SRS) transmitted by the receiver;

calculating an average channel gain on downlink channels using the estimated uplink spatial correlation matrix; and

determining the beam having the greatest gain for the transmitter from among beams belonging to the one of the resource reuse groups having the index and the average channel gain on the downlink channels.

3. The beamforming method of claim 1, wherein sorting the beams comprises grouping beams having a minimum interference with each other into a resource reuse group.

4. The beamforming method of claim 1, further comprising transmitting information including at least one of a number of beams reusing each resource element, each Channel State Information Reference Signal (CSI-RS) resource, and a power allocated for each beam for use in channel quality information estimation at the receiver, through higher layer signaling.

5. An information feedback method in a wireless communication system, the information feedback method comprising the steps of:

receiving beams sorted into a number of resource reuse groups through resources allocated for respective resource reuse groups, from a transmitter;

generating feedback information on at least one antenna port, based on the received beams, for use in determining a beam having a greatest gain at the transmitter; and

transmitting the feedback information to the transmitter,

wherein the beams are formed by precoding per-beam signals to be transmitted through respective antenna ports of the transmitter with respective beamforming vectors.

6. The information feedback method of claim 5, wherein generating the feedback information comprises:

determining an index of one of the resource reuse groups having a greatest channel gain in association with a downlink channel and a beamforming vector; and

transmitting the index to the transmitter.

7. The information feedback method of claim 5, further comprising receiving information including at least one of a number of beams reusing each resource element, each Channel State Information Reference Signal (CSI-RS) resource, and a power allocated for each beam for use in channel quality information estimation at a receiver, through higher layer signaling.

8. The information feedback method of claim 7, further comprising:

estimating channel quality information using the information received through higher layer signaling; and

transmitting the channel quality information to the transmitter.

9. The information feedback method of claim 8, wherein the channel quality information comprises at least one of a reception available signal-to-interference and noise ratio, a data rate available from the transmitter to the receiver, and a modulation and coding scheme available for transmission from the transmitter to the receiver.

12. The transmitter of claim 9, wherein the control unit controls grouping of the beams having a minimum interference with each other into a resource reuse group.

13. The transmitter of claim 9, wherein the control unit controls transmission of information including at least one of a number of beams reusing each resource element, each Channel State Information Reference Signal (CSI-RS) resource, and a power allocated for each beam for use in channel quality information estimation at the receiver, through higher layer signaling.

10. A transmitter equipped with a plurality of antenna ports for beamforming in a wireless communication system, the transmitter comprising:

a radio communication unit that communicates signals with a receiver; and

a control unit that controls generation of signals for beams to be transmitted through corresponding antenna ports, formation of the beams by precoding the signals with beamforming vectors, sorting of the beams into a number of resource reuse groups based on a resource that is to be shared, transmission of the beams, using resources allocated per group, to a receiver, selection of a beam having a greatest gain for the transmitter using feedback information on at least one of the antenna ports, which is transmitted by the receiver, and allocation of a transmission resource for the selected beam.

11. The transmitter of claim 10, wherein the control unit controls reception of an index of one of the resource reuse groups having a greatest gain in association with a downlink channel and a beamforming vector, from the receiver, estimation of an uplink spatial correlation matrix using an uplink Sounding Reference Signal (SRS) transmitted by the receiver, calculation of an average channel gain on downlink channels using the estimated uplink spatial correlation matrix, and determination of the beam having the greatest gain for the transmitter from among beams belonging to the one of the resource reuse groups having the index and the average channel gain on the downlink channels.

14. A receiver for transmitting feedback information to a transmitter in a wireless communication system, the receiver comprising:

a radio communication unit which communicates signals with the transmitter; and

a control unit which controls reception of beams sorted into a number of resource reuse groups through resources allocated for respective resource reuse groups, from a transmitter, generation of feedback information on at least one antenna port, based on the received beams, for use in determining a beam having a greatest gain at the transmitter, and transmission of the feedback information to the transmitter, wherein the beams are formed by precoding per-beam signals to be transmitted through respective antenna ports of the transmitter with respective beamforming vectors.

15. The receiver of claim 14, wherein the control unit controls determination of an index of one of the resource reuse groups having a greatest channel gain in association with a downlink channel and a beamforming vector, and transmission of the index to the transmitter.

16. The receiver of claim 14, wherein the control unit controls reception of information including at least one of a number of beams reusing each resource element, each Channel State Information Reference Signal (CSI-RS) resource, and a power allocated for each beam for use in channel quality information estimation at the receiver, through higher layer signaling.

17. The receiver of claim 16, wherein the control unit controls estimation of channel quality information using the information received through higher layer signaling, and transmission of the channel quality information to the transmitter.

18. The receiver of claim 16, wherein the channel quality information comprises at least one of a reception available signal-to-interference and noise ratio, a data rate available from the transmitter to the receiver, and modulation and a coding scheme available for transmission from the transmitter to the receiver.