DOWNLINK TRANSMISSION IN A MU-MIMO SYSTEM

• US 20150003350A1
• Filed: 12/14/2012
• Published: 01/01/2015
• Est. Priority Date: 12/21/2011
• Status: Active Grant

• Current Assignee: Orange S.A.
• Original Assignee: Orange S.A.
• Inventors: Yu, Yifan
• Granted Patent: US 9,723,625 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 7/0626 Channel coefficients, e.g. channel state information [CSI]
• 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: H04B 7/0663 using vector or matrix manipulations
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04W 72/1273 of downlink data flows

Abstract

A method is provided for managing a downlink transmission in a Multi User-Multiple Input Multiple Output (MU-MIMO) system. The MU-MIMO system includes a base station and a set of remote radio units connected to the base station. The method includes: obtaining large scale fading data related to a large scale fading over uplink transmission associated with a user equipment (UE); generating a UE-specific channel vector by using the large scale fading data; and scheduling a downlink transmission by using the UE-specific channel vector.

Claims

1. Method for managing a downlink transmission in a Multi User-Multiple Input Multiple Output MU-MIMO system, the MU-MIMO system comprising a base station (1), and a set of remote radio units (2a-2c) connected to the base station, the method comprising steps of:

/1/ obtaining large scale fading data related to a large scale fading over uplink transmission associated with a user equipment (4a-4d),

/2/ generating a UE-specific channel vector by using the large scale fading data, and

/3/ scheduling a downlink transmission by using the UE-specific channel vector.

2. Method according to claim 1, wherein the said large scale fading data is obtained by performing a large scale fading estimation at the base station (1).

3. Method according to claim 2, wherein the estimation is performed by using a Sounding Reference Signal SRS received from a user equipment (4a-4d).

4. Method according to claim 3, wherein step /1/ comprises, at the base station (1), sorting remote radio units antennas sensed by the user equipment (4a-4d) into two sets Di and Ui which are expressed as:

D_i={j;

l_ij>

l_ik, ∀

k∈

U_i}

U_i={j;

l_ik>

l_ij, ∀

k∈

D_i}

where l_ij refers to an estimation of large scale channel gain from user equipment i to antenna j.

5. Method according to claim 1, wherein the said large scale fading data is obtained by performing a large scale fading estimation at a user equipment (4a-4d), the large scale fading data being received at the base station (1) from the user equipment.

6. Method according to claim 5, wherein the estimation is performed by using a Channel State Indication CSI-RS received at the user equipment from the base station.

7. Method according to claim 6, wherein step /1/ comprises, at the user equipment, sorting remote radio units antennas sensed by the user equipment into two sets Di and Ui which are expressed as:

D_i={j;

l_ij>

l_ik, ∀

k∈

U_i}

U_i={j;

l_ik>

l_ij, ∀

k∈

D_i}

where l_ij refers to an estimation of large scale channel gain from user equipment i to antenna j.

8. Method according to claim 4 or 7, wherein step /2/ comprises, at the base station (1), calculating a UE-specific channel vector as:

9. Computer program product comprising a computer readable medium, having thereon a computer program comprising program instructions, the computer program being loadable into a data-processing unit and adapted to cause the data-processing unit to carry out the steps of claim I when the computer program is run by the data-processing unit.

10. Base station of a Multi User-Multiple Input Multiple Output MU-MIMO system, the MU-MIMO system further comprising a set of remote radio units (2a-2c) connected to the base station (1), the base station being configured to:

/1/ obtain large scale fading data related to a large scale fading over uplink transmission associated with a user equipment (4a-4d),

/2/ generate a UE-specific channel vector by using the large scale fading data, and

/3/ schedule a downlink transmission by using the UE-specific channel vector.

11. Multi User-Multiple Input Multiple Output MU-MIMO system, comprising a base station (1) according to claim 10, and a set of remote radio units (2a-2c) connected to the base station (1).