Efficient large-scale multiple input multiple output communications

Patent metadata

Field	Value
Publication number	US-9413474-B2
Application number	US-201514738230-A
Country	US
Kind code	B2
Filing date	Jun 12, 2015
Priority date	Jun 12, 2014
Publication date	Aug 9, 2016
Grant date	Aug 9, 2016

Abstract

Methods and systems for beam forming include measuring channel state information for a set of different codebook entries. An angle of arrival (AoA) distribution is determined with a processor using compressive testing based on the measured channel state information. A set of phase shift values is determined based on the determined AoA to perform phased array beamforming.

First claim

The invention claimed is:

1. A method for beam forming, implemented in a user equipment used in a communication system, the method comprising:
measuring channel state information for each of a set of different codebook entries;
determining an angle of arrival (AoA) distribution with a processor using compressive sensing based on the measured channel state information;
determining a set of phase shift values based on the determined AoA; and
controlling a set of phase shifters in accordance with respective phase shift values of the determined set of phase shift values to perform phased array beamforming.

2. The method of claim 1 , wherein the CSI is related to the AoA by an inverse discrete space Fourier transform.

3. The method of claim 2 , wherein determining the AoA comprises solving:
â l k (θ)=arg min ∥ a l k (θ)∥ 2

s. t. ĥ s,c (1) =b (v) F (−1) a l k (θ), 1 ≦v≦V

where a l k (θ) is an arbitrary distribution of signal energy given the incident angle θ of the signal, â l k (θ) represents a specific distribution of energy, ĥ s,c (1) is a CSI measurement taken with codebook entries b (1) , . . . , b (V) , where 1≦v≦V and V is a number of total CSI measurements, and where F −1 is an inverse discreet space Fourier transform matrix.

4. The method of claim 1 , wherein a set of phase shift values is selected to maximize signal-to-leakage-power ratio (SLR) between a phased-array antenna and a respective user.

5. The method of claim 4 , wherein the SLR is measured as a ratio between the AoA distribution from the phased-array antenna to the respective user and a sum of AoA distributions from the phased-array antenna and concurrently active users in adjacent cells.

6. A base station used in a communications system, comprising:
a channel state information module configured to measure channel state information for each of a set of different codebook entries;
an angle of arrival (AoA) module comprising a processor configured to determine an AoA distribution using compressive sensing based on the measured channel state information; and
a phase control module configured to determine a set of phase shift values based on the determined AoA to perform phased array beamforming.

7. The system of claim 6 , wherein the CSI is related to the AoA by an inverse discrete space Fourier transform.

8. The system of claim 7 , wherein determining the AoA comprises solving:
â l k (θ)=arg min ∥ a l k (θ)∥ 2

s. t. ĥ s,c (1) =b (v) F (−1) a l k (θ), 1 ≦v≦V

where a l k (θ) is an arbitrary distribution of signal energy given the incident angle θ of the signal, â l k (θ) represents a specific distribution of energy, ĥ s,c (1) is a CSI measurement taken with codebook entries b (1) , . . . , b (V) , where 1≦v≦V and V is a number of total CSI measurements, and where F −1 is an inverse discreet space Fourier transform matrix.

9. The system of claim 6 , wherein the phase control module is further configured to select a set of phase shift values to maximize signal-to-leakage-power ratio (SLR) between a phased-array antenna and a respective user.

10. The system of claim 9 , wherein the SLR is measured as a ratio between the AoA distribution from the phased-array antenna to the respective user and a sum of AoA distributions from the phased-array antenna and concurrently active users in adjacent cells.

Assignees

• Nec Lab America Inc
• Nec Corp

Inventors

• Chai Eugene
• Xie Xiufeng
• Khojastepour Mohammad
• Sundaresan Karthikeyan
• Rangarajan Sampath

Classifications

• H04B7/0626 Primary

  Channel coefficients, e.g. channel state information [CSI] · CPC title

• H04B7/0617

  for beam forming · CPC title

• H04B17/104 Primary

  of other parameters, e.g. DC offset, delay or propagation times · CPC title

• H04B7/0452

  Multi-user MIMO systems · CPC title

• H04B17/309 Primary

  Measuring or estimating channel quality parameters · CPC title