Channel Feedback for Vertical and Full-Dimensional Beamforming

• US 20140198751A1
• Filed: 01/15/2014
• Published: 07/17/2014
• Est. Priority Date: 01/17/2013
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Laboratories America Inc (NEC Corporation)
• Inventors: Prasad, Narayan, Yue, Guosen, Rangarajan, Sampath
• Granted Patent: US 10,020,859 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0632 Channel quality parameters, e.g. channel quality indicator [CQI]
• CPC Class Codes: H04B 7/0639 Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0073 Allocation arrangements that take into account other cell interferences for intercell interference mitigation or co-ordination in orthogonal multiplex systems H04J11/005

Abstract

A method implemented in a base station used in a wireless communications system where different antenna arrays are employed for transmissions to different co-scheduled users in a cell is disclosed. The method includes configuring multiple channel state information (CSI) processes for a user equipment (UE), and configuring, for the UE, a plurality of non-zero power (NZP) CSI reference signal (RS) resources, each of which is associated with an antenna array. Other apparatuses, systems, and methods also are disclosed.

Claims

1. A method implemented in a base station used in a wireless communications system where different antenna arrays are employed for transmissions to different co-scheduled users in a cell, the method comprising:

configuring multiple channel state information (CSI) processes for a user equipment (UE); and

configuring, for the UE, a plurality of non-zero power (NZP) CSI reference signal (RS) resources, each of which is associated with an antenna array.

2. The method as in claim 1,

wherein, based on channel estimation using each NZP CSI-RS resource, the UE transmits CSI feedback for each NZP CSI-RS resource, and

wherein the number of the multiple CSI processes is the same as the number of NZP CSI-RS resources.

3. The method as in claim 1, further comprising:

configuring multiple interference measurement resources (IMRs) for the UE.

4. The method as in claim 1, further comprising:

configuring a separate resource for interference measurement.

5. The method as in claim 1,

wherein, if no interference measurement resource (IMR) is configured, the UE measures interference based on a received signal from an NZP-CSI-RS resource and subtracts an estimate of a channel part, and

wherein, if an IMR is configured, the UE computes a CSI report using the IMR for each CSI process.

6. The method as in claim 1, further comprising:

configuring the multiple CSI processes for one NZP CSI-RS resource; and

configuring, for one of the multiple CSI processes designated as a reference CSI process, the UE to transmit CSI feedback assuming single-user (SU) multiple-input and multiple-output (MIMO).

7. The method as in claim 6, further comprising:

configuring, for the rest of the multiple CSI processes, the UE to emulate interference based on an estimated channel from other NZP CSI-RS resources, assuming isotropic interference in a complex space or isotropic interference along an orthogonal subspace of a preferred precoder for a channel in the reference CSI process.

8. The method as in claim 6, further comprising:

configuring, for the rest of the multiple CSI processes, the UE to compute a best or worst companion precoding and a resulting channel quality indicator (CQI), assuming that there is a co-scheduled user on each other channel.

9. A method implemented in a user equipment (UE) used in a wireless communications system where different antenna arrays are employed for transmissions to different co-scheduled users in a cell, the method comprising:

receiving multiple channel state information (CSI) processes; and

receiving a plurality of non-zero power (NZP) CSI reference signal (RS) resources, each of which is associated with an antenna array.

10. The method as in claim 9, further comprising:

based on channel estimation using each NZP CSI-RS resource, transmitting CSI feedback for each NZP CSI-RS resource,

wherein the number of the multiple CSI processes is the same as the number of NZP CSI-RS resources.

11. The method as in claim 9,

wherein multiple interference measurement resources (IMRs) are configured for the UE.

12. The method as in claim 9,

wherein a separate resource for interference measurement is configured.

13. The method as in claim 9, further comprising:

if no interference measurement resource (IMR) is configured, measuring interference based on a received signal from a CSI-RS resource and subtracting a channel part; and

if an IMR is configured, computing a CSI report using the IMR for each CSI process.

14. The method as in claim 9,

wherein the multiple CSI processes is configured for one NZP CSI-RS resource, and

wherein, for one of the multiple CSI processes as a reference CSI process, the UE transmits CSI feedback assuming single-user (SU) multiple-input and multiple-output (MIMO).

15. The method as in claim 14,

wherein, for the rest of the multiple CSI processes, the UE emulates interference based on an estimate channel from other NZP CSI-RS resources, assuming isotropic interference in a complex space or isotropic interference along an orthogonal subspace of a preferred precoder for a channel in the reference CSI process.

16. The method as in claim 14,

wherein, for the rest of the multiple CSI processes, the UE computes a best or worst companion precoding and a resulting channel quality indicator (CQI), assuming that there is a co-scheduled user on other channels.

17. A wireless communications system where different antenna arrays are employed for transmissions to different co-scheduled users in a cell, the method comprising:

a user equipment (UE); and

a base station configuring multiple channel state information (CSI) processes to the UE,

wherein a plurality of non-zero power (NZP) CSI reference signal (RS) resources, each of which is associated with an antenna array, are configured for the UE.