Method and apparatus for multiple-input multiple-output operation

• US 10,355,759 B2
• Filed: 12/12/2016
• Issued: 07/16/2019
• Est. Priority Date: 08/12/2011
• Status: Active Grant

• Current Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Inventors: Nayeb Nazar, Shahrokh, Iyer, Lakshmi R., Olesen, Robert L., Pelletier, Benoit, Raghavan, Manasa, Lee, Moon-il
• Primary Examiner(s): Li, Guang W
• Application Number:
  US15/375,528
• Publication Number:
  US 20170093469A1
• Time in Patent Office: 946 Days
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04W 72/04 Wireless resource allocation

Abstract

An eNode-B for a multi-user multiple-input multiple-output (MU-MIMO) downlink transmission to at least first and second wireless transmit/receive units (WTRUs) via resource elements (REs) of first and second spatial layers, the eNode-B comprising a transmitter and a processor, the processor coupled to the transmitter. The processor configured to generate the MU-MIMO downlink transmission including: allocating a first set of the REs, as first resources, to the first spatial layer for the first WTRU, and a second set of the REs, as second resources, to the second spatial layer for the second WTRU, mapping a first WTRU-specific reference signal (RS) associated with the first WTRU on a subset of the first resources, and a second WTRU-specific RS associated with the second WTRU on a subset of the second resources, muting allocated REs of the first resources overlapping with the subset of the second resources used for the second WTRU-specific RS, and allocated REs of the second resources overlapping with the subset of the first resources used for the first WTRU-specific RS. The transmitter configured to send the MU-MIMO downlink transmission.

Claims

1. A method implemented by an eNode-B for transmitting a multi-user multiple-input multiple-output (MU-MIMO) downlink transmission to at least first and second wireless transmit/receive units (WTRUs) via resource elements (REs) of first and second spatial layers, wherein the REs are allocated to resource blocks, and the resource blocks include WTRU-specific reference signals for a plurality of WTRUs and the MU-MIMO downlink transmission, the method comprising:

generating, by the eNode-B, for the MU-MIMO downlink transmission, a first set of the REs allocated by the eNode-B as first resources to the first spatial layer for the first WTRU, and a second set of the REs allocated by the eNode-B as second resources to the second spatial layer for the second WTRU,

wherein a first WTRU-specific reference signal (RS) associated with the first WTRU is mapped by the eNode-B to a subset of the first resources,

wherein a second WTRU-specific RS associated with the second WTRU is mapped by the eNode-B to a subset of the second resources,

wherein the first and second WTRU-specific reference signals for different sub-groups of at least two antenna ports are allocated onto different subcarriers in a frequency domain,

wherein the first and second WTRU-specific reference signals of the same sub-group of antennas ports are each applied with a different orthogonal cover code in a time domain,

wherein allocated REs of the first resources overlapping with the subset of the second resources used for the second WTRU-specific RS are muted by the eNode-B, and

wherein allocated REs of the second resources overlapping with the subset of the first resources used for the first WTRU-specific RS are muted by the eNode-B; and

transmitting, by the eNode-B, the MU-MIMO downlink transmission,

wherein REs used for the MU-MIMO downlink transmission are rate matched around the first subset of resources on at least one antenna port in a first sub-group and are rate matched around the second subset of resources on at least one antenna port in a second sub-group.

2. The method of claim 1, wherein muted REs on a given spatial layer correspond to REs that no data is transmitted on for the given spatial layer.

3. The method of claim 1, wherein four antenna ports are used to support up to eight spatial layers.

4. The method of claim 1, wherein the first WTRU and the second WTRU are paired for the MU-MIMO downlink transmission based on spatial correlation.

5. The method of claim 1, wherein a bandwidth assigned for the first WTRU is different from a bandwidth assigned for the second WTRU.

6. The method of claim 5, further comprising:

avoiding applying a scrambling sequence to the first WTRU-specific RS on a condition that a bandwidth assigned to the second WTRU is different.

7. The method of claim 1, further comprising:

transmitting largest bandwidth information among the plurality of WTRUs paired for the MU-MIMO downlink transmission.

8. The method of claim 1, wherein at least one WTRU-specific RS corresponds to at least one MU-MIMO downlink transmission.

9. The method of claim 1, wherein the resource blocks include at least the first WTRU-specific RS and the second WTRU-specific RS.

10. An eNode-B for transmitting a multi-user multiple-input multiple-output (MU-MIMO) downlink transmission to at least first and second wireless transmit/receive units (WTRUs) via resource elements (REs) of first and second spatial layers, wherein the REs are allocated to resource blocks, and the resource blocks include WTRU-specific reference signals for a plurality of WTRUs and the MU-MIMO downlink transmission, the eNode-B comprising:

a processor, coupled to a transmitter, the processor configured to;

generate, for the MU-MIMO downlink transmission, a first set of the REs allocated by the eNode-B as first resources to the first spatial layer for the first WTRU, and a second set of the REs allocated by the eNode-B as second resources;

to the second spatial layer for the second WTRU,

wherein a first WTRU-specific reference signal (RS) associated with the first WTRU is mapped by the eNode-B to a subset of the first resources,

wherein a second WTRU-specific RS associated with the second WTRU is mapped by the eNode-B to a subset of the second resources,

wherein the first and second WTRU-specific reference signals for different sub-groups of at least two antenna ports are allocated onto different subcarriers in a frequency domain,

wherein the first and second WTRU-specific reference signals of the same sub-group of antennas ports are each applied with a different orthogonal cover code in a time domain,

wherein allocated REs of the first resources overlapping with the subset of the second resources used for the second WTRU-specific RS are muted by the eNode-B,

wherein allocated REs of the second resources overlapping with the subset of the first resources used for the first WTRU-specific RS are muted by the eNode-B; and

the transmitter configured to transmit the MU-MIMO downlink transmission,

wherein REs used for the MU-MIMO downlink transmission are rate matched around the first subset of resources on at least one antenna port in a first sub-group and are rate matched around the second subset of resources on at least one antenna port in a second sub-group.

11. The eNode-B of claim 10, wherein muted REs on a given spatial layer correspond to REs that no data is transmitted on for the given spatial layer.

12. The eNode-B of claim 10, wherein four antenna ports are used to support up to eight spatial layers.

13. The eNode-B of claim 10, wherein the first WTRU and the second WTRU are paired for the MU-MIMO downlink transmission based on spatial correlation.

14. The eNode-B of claim 10, wherein a bandwidth assigned for the first WTRU is different from a bandwidth assigned for the second WTRU.

15. The eNode-B of claim 14, wherein the processor is further configured to avoid applying a scrambling sequence to the first WTRU-specific RS on a condition that a bandwidth assigned to the second WTRU is different.

16. The eNode-B of claim 10, wherein the transmitter is further configured to transmit largest bandwidth information among the plurality of WTRUs paired for the MU-MIMO downlink transmission.

17. The eNode-B of claim 10, wherein at least one WTRU-specific RS corresponds to at least one MU-MIMO downlink transmission.

18. The eNode-B of claim 10, the resource blocks include at least the first WTRU-specific RS and the second WTRU-specific RS.