SIGNALING ADAPTED CSI-RS PERIODICITIES IN ACTIVE ANTENNA SYSTEMS

• US 20160143055A1
• Filed: 11/17/2015
• Published: 05/19/2016
• Est. Priority Date: 11/18/2014
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Nammi, Sairamesh, Frenne, Mattias, Harrison, Mark, Kazmi, Muhammad
• Granted Patent: US 9,999,073 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01Q 21/28 Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0684 using different training sequences per antenna
• CPC Class Codes: H04B 7/0689 using different transmission schemes, at least one of them being a diversity transmission scheme
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 74/006 in the downlink, i.e. towards the terminal
• CPC Class Codes: H04W 74/04 Scheduled access hybrid access H04W74/02

Abstract

A method in a network node is disclosed. The method comprises grouping a plurality of antenna ports corresponding to a plurality of channel state information reference signals (CSI-RS) into at least a first CSI-RS antenna port group and a second CSI-RS antenna port group, and determining, based at least in part on one or more criteria, a first transmission periodicity for the first CSI-RS antenna port group and a second transmission periodicity for the second CSI-RS antenna port group. The method further comprises transmitting, to one or more user equipment, the CSI-RS corresponding to the antenna ports in the first CSI-RS antenna port group according to the determined first transmission periodicity, and transmitting, to the one or more user equipment, the CSI-RS corresponding to the antenna ports in the second CSI-RS antenna port group according to the determined second transmission periodicity.

Claims

1. A method in a network node, comprising:

grouping a plurality of antenna ports corresponding to a plurality of channel state information reference signals (CSI-RS) into at least a first CSI-RS antenna port group and a second CSI-RS antenna port group;

determining, based at least in part on one or more criteria, a first transmission periodicity for the first CSI-RS antenna port group and a second transmission periodicity for the second CSI-RS antenna port group;

transmitting, to one or more user equipment, the CSI-RS corresponding to the antenna ports in the first CSI-RS antenna port group according to the determined first transmission periodicity; and

transmitting, to the one or more user equipment, the CSI-RS corresponding to the antenna ports in the second CSI-RS antenna port group according to the determined second transmission periodicity.

2. The method of claim 1, further comprising communicating information about the determined transmission periodicities to the one or more user equipment.

3. The method of claim 2, wherein the information communicated to the one or more user equipment about the determined transmission periodicities comprises information about the determined transmission periodicity of each CSI-RS antenna port.

4. The method of claim 2, wherein the information communicated to the one or more user equipment about the determined transmission periodicities comprises information about the determined transmission periodicity for the first and second CSI-RS antenna port groups.

5. The method of claim 1, wherein the first CSI-RS antenna port group and second CSI-RS antenna port group are predefined.

6. The method of claim 1, further comprising configuring the one or more user equipment with a first channel state information (CSI) reporting periodicity for the CSI-RS corresponding to the first group of CSI-RS antenna ports and a second CSI reporting periodicity for the CSI-RS corresponding to the second group of CSI-RS antenna ports.

7. The method of claim 1, further comprising receiving, from the one or more user equipment, a recommended value or range of values for the first transmission periodicity of the first CSI-RS antenna port group and the second transmission periodicity of the second CSI-RS antenna port group.

8. The method of claim 1, wherein the one or more criteria comprise one or more of:

an application or use case;

a Doppler metric of one or more user equipment;

a speed of the one or more user equipment; and

a recommendation of the one or more user equipment.

9. The method of claim 8, wherein:

the one or more criteria comprise the application or use case; and

the first transmission periodicity of the first CSI-RS antenna port group is determined independently from the second transmission periodicity of the second CSI-RS antenna port group.

10. The method of claim 9, wherein:

the first CSI-RS antenna port group comprises a subset of the plurality of antenna ports corresponding to CSI-RS used to compute CSI in the horizontal (azimuth) direction; and

the second CSI-RS antenna port group comprises a subset of the plurality of antenna ports corresponding to CSI-RS used to compute CSI in the vertical (elevation) domain.

11. The method of claim 8, wherein the one or more criteria comprise the Doppler metric or speed of the one or more user equipment, and the method further comprises:

comparing the Doppler metric or speed of the one or more user equipment to a first threshold value; and

determining the first transmission periodicity of the first CSI-RS antenna port group and the second transmission periodicity of the second CSI-RS antenna port group based at least in part on the comparison.

12. The method of claim 11, wherein the Doppler metric or speed of the one or more user equipment is below the first threshold value, and the method further comprises:

setting the value of the second transmission periodicity of the second CSI-RS antenna port group to a higher value than the first transmission periodicity of the first CSI-RS antenna group such that the CSI-RS corresponding to the second CSI-RS antenna port group are transmitted less frequently than the CSI-RS corresponding to the first CSI-RS antenna port group.

13. The method of claim 1, wherein the first and second transmission periodicities are measured in transmission time intervals.

14. The method of claim 1, further comprising:

configuring the one or more user equipment to report CSI feedback calculated using the first CSI-RS antenna port group;

determining a need for CSI feedback calculated using the first CSI-RS antenna port group and the second CSI-RS antenna port group;

triggering the one or more user equipment to report CSI feedback calculated using the first CSI-RS antenna port group and the second CSI-RS antenna port group.

15. The method of claim 14, wherein triggering the one or more user equipment to report CSI feedback calculated using the first CSI-RS antenna port group and the second CSI-RS antenna port group comprises:

transmitting, to the one or more user equipment, one of a downlink grant and a medium access control element.

16. The method of claim 14, further comprising receiving, from the one or more user equipment:

a first CSI feedback report corresponding to the first CSI-RS antenna port group; and

a second CSI feedback report corresponding to the second CSI-RS antenna port group.

17. A network node, comprising:

one or more processors, the one or more processors configured to;

group a plurality of antenna ports corresponding to a plurality of channel state information reference signals (CSI-RS) into at least a first CSI-RS antenna port group and a second CSI-RS antenna port group;

determine, based at least in part on one or more criteria, a first transmission periodicity for the first CSI-RS antenna port group and a second transmission periodicity for the second CSI-RS antenna port group;

transmit, to one or more user equipment, the CSI-RS corresponding to the antenna ports in the first CSI-RS antenna port group according to the determined first transmission periodicity; and

transmit, to the one or more user equipment, the CSI-RS corresponding to the antenna ports in the second CSI-RS antenna port group according to the determined second transmission periodicity.

18. The network node of claim 17, wherein the one or more processors are further configured to communicate information about the determined transmission periodicities to the one or more user equipment.

19. The network node of claim 18, wherein the information about the determined transmission periodicities comprises information about the determined transmission periodicity of each CSI-RS antenna port.

20. The network node of claim 18, wherein the information about the determined transmission periodicities comprises information about the determined transmission periodicity for the first and second CSI-RS antenna port groups.

21. The network node of claim 17, wherein the first CSI-RS antenna port group and second CSI-RS antenna port group are predefined.

22. The network node of claim 17, wherein the one or more processors are further configured to configure the one or more user equipment with a first channel state information (CSI) reporting periodicity for the CSI-RS corresponding to the first group of CSI-RS antenna ports and a second CSI reporting periodicity for the CSI-RS corresponding to the second group of CSI-RS antenna ports.

23. The network node of claim 17, wherein the one or more processors are further configured to receive, from the one or more user equipment, a recommended value or range of values for the first transmission periodicity of the first CSI-RS antenna port group and the second transmission periodicity of the second CSI-RS antenna port group.

24. The network node of claim 17, wherein the one or more criteria comprise one or more of:

an application or use case;

a Doppler metric of one or more user equipment;

a speed of the one or more user equipment; and

a recommendation of the one or more user equipment.

25. The network node of claim 24, wherein:

the one or more criteria comprise the application or use case; and

the one or more processors are configured to determine the first transmission periodicity of the first CSI-RS antenna port group independently from the second transmission periodicity of the second CSI-RS antenna port group.

26. The network node of claim 25, wherein:

the first CSI-RS antenna port group comprises a subset of the plurality of antenna ports corresponding to CSI-RS used to compute CSI in the horizontal (azimuth) direction; and

the second CSI-RS antenna port group comprises a subset of the plurality of antenna ports corresponding to CSI-RS used to compute CSI in the vertical (elevation) domain.

27. The network node of claim 24, wherein the one or more criteria comprise the Doppler metric or speed of the one or more user equipment, and the one or more processors are further configured to:

compare the Doppler metric or speed of the one or more user equipment to a first threshold value; and

determine the first transmission periodicity of the first CSI-RS antenna port group and the second transmission periodicity of the second CSI-RS antenna port group based at least in part on the comparison.

28. The network node of claim 27, wherein the Doppler metric or speed of the one or more user equipment is below the first threshold value, and the one or more processors are further configured to:

set the value of the second transmission periodicity of the second CSI-RS antenna port group to a higher value than the first transmission periodicity of the first CSI-RS antenna group such that the CSI-RS corresponding to the second CSI-RS antenna port group are transmitted less frequently than the CSI-RS corresponding to the first CSI-RS antenna port group.

29. The network node of claim 17, wherein the first and second transmission periodicities are measured in transmission time intervals.

30. The network node of claim 17, wherein the one or more processors are further configured to:

configure the one or more user equipment to report CSI feedback calculated using the first CSI-RS antenna port group;

determine a need for CSI feedback calculated using the first CSI-RS antenna port group and the second CSI-RS antenna port group;

trigger the one or more user equipment to report CSI feedback calculated using the first CSI-RS antenna port group and the second CSI-RS antenna port group.

31. The network node of claim 30, wherein the one or more processors configured to trigger the one or more user equipment to report CSI feedback calculated using the first CSI-RS antenna port group and the second CSI-RS antenna port group comprise one or more processors configured to:

transmit, to the one or more user equipment, one of a downlink grant and a medium access control element.

32. The network node of claim 30, wherein the one or more processors are further configured to receive, from the one or more user equipment:

a first CSI feedback report corresponding to the first CSI-RS antenna port group; and

a second CSI feedback report corresponding to the second CSI-RS antenna port group.