Downlink transmission in a MU-MIMO system

• US 9,723,625 B2
• Filed: 12/14/2012
• Issued: 08/01/2017
• Est. Priority Date: 12/21/2011
• Status: Active Grant

• Current Assignee: Orange S.A.
• Original Assignee: Orange S.A.
• Inventors: Yu, Yifan
• Primary Examiner(s): Young, Steve
• Application Number:
  US14/367,722
• Publication Number:
  US 20150003350A1
• Time in Patent Office: 1,691 Days
• Field of Search: None
• 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. A method comprising:

managing a downlink transmission in a Multi User-Multiple Input Multiple Output MU-MIMO system, the MU-MIMO system comprising a base station, and a set of remote radio units connected to the base station, the method comprising the following acts performed by the base station;

obtaining large scale fading data related to a large scale fading over uplink transmission associated with a user equipment (UE), the act of obtaining comprising 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,∀

kε

U_i}

U_i={j;

l_ik>

l_ij,∀

kε

D_i}

 

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

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

scheduling the downlink transmission in the MU-MIMO system by using the UE-specific channel vector.

2. The method according to claim 1, wherein the said large scale fading data is obtained by the base station performing a large scale fading estimation.

3. The method according to claim 2, further comprising:

receiving a Sounding Reference Signal SRS received from the user equipment,

wherein the estimation is performed by the base station using the Sounding Reference Signal SRS received from the user equipment.

4. The method according to claim 1, wherein the said large scale fading data is obtained by performing a large scale fading estimation by a user equipment, and wherein the act of obtaining the large scale fading data comprises the base station receiving the large scale fading estimation from the user equipment.

5. The method according to claim 4, wherein the method comprises the base station transmitting a Channel State Indication CSI-RS to the user equipment, and wherein the estimation is performed by using the Channel State Indication CSI-RS received at the user equipment from the base station.

6. The method according to claim 1, wherein the act of generating comprises the base station calculating a UE-specific channel vector as:

7. A non-transitory computer readable medium comprising a computer program product and 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 of a base station to carry out a method when the computer program is run by the data-processing unit, the method comprising:

managing a downlink transmission by the base station in a Multi User-Multiple Input Multiple Output MU-MIMO system, the MU-MIMO system comprising the base station, and a set of remote radio units connected to the base station, wherein managing comprises;

obtaining large scale fading data related to a large scale fading over uplink transmission associated with a user equipment (UE), the act of obtaining comprising 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,∀

kε

U_i}

U_i={j;

l_ik>

l_ij,∀

kε

D_i}

 

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

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

scheduling a downlink transmission in the MU-MIMO system by using the UE-specific channel vector.

8. A 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 connected to the base station, the base station comprising:

a non-transitory computer-readable medium comprising instructions stored thereon;

a data processing unit configured by the instructions to perform acts of;

managing a downlink transmission in the Multi User-Multiple Input Multiple Output MU-MIMO system, wherein managing comprises;

obtaining large scale fading data related to a large scale fading over uplink transmission associated with a user equipment, the act of obtaining comprising 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,∀

kε

U_i}

U_i={j;

l_ik>

l_ij,∀

kε

D_i}

 

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

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

scheduling the downlink transmission in the MU-MIMO system by using the UE-specific channel vector.

9. A Multi User-Multiple Input Multiple Output MU-MIMO system, comprising the base station according to claim 8, and the set of remote radio units connected to the base station.