Targeted ratio of signal power to interference plus noise power for enhancement of a multi-user detection receiver

Patent metadata

Field	Value
Publication number	US-11005507-B2
Application number	US-202016900116-A
Country	US
Kind code	B2
Filing date	Jun 12, 2020
Priority date	Jun 14, 2019
Publication date	May 11, 2021
Grant date	May 11, 2021

Abstract

According to some embodiments, in a multi-user detection (MUD) receiver, a method for identifying a beam which produces a specific signal-to-interference-plus-noise ratio (SINR) can include: determining a maximum output SINR; determining beam weights to achieve a target SINR using the determined maximum output SINR; applying the beam weights to one or more received signals to generate a beamformed signal having the target SINR, one or more of the received signals having a signal of interest (SOI), one or more interfering signals, and noise; and providing the beamformed signal to a multi-user detection unit to recover the SOI.

First claim

The invention claimed is:

1. In a multi-user detection (MUD) receiver, a method for identifying a beam which produces a specific signal-to-interference-plus-noise ratio (SINR), the method comprising:
determining a maximum output SINR;
determining beam weights to achieve a target SINR using the determined maximum output SINR;
applying the beam weights to one or more received signals to generate a beamformed signal having the target SINR, one or more of the received signals comprised of a signal of interest (SOI), one or more interfering signals, and noise; and
providing the beamformed signal to a multi-user detection unit to recover the SOI.

2. The method of claim 1 , wherein determining the maximum output SINR comprises determining beam weights that maximize SINR.

3. The method of claim 2 , wherein determining the beam weights that maximize SINR includes using at least one of:
minimum variance distortion-less response (MVDR) beamforming;
space time adaptive processing (STAP) beamforming; or
space time frequency adaptive processing (STFAP) beamforming.

4. The method of claim 2 , wherein determining the maximum output SINR includes estimating the maximum output SINR using a closed form solution.

5. The method of claim 2 , wherein determining the maximum output SINR further comprises applying the beam weights that maximize SINR to a model of the SOI and a model of the noise plus interference to determine the maximum output SINR.

6. The method of claim 2 , wherein determining the maximum output SINR comprises:
applying the beam weights that maximize SINR to the received signals to obtain signal samples; and
determining the maximum output SINR using the obtained signal samples.

7. The method of claim 1 , wherein determining the beam weights to achieve the target SINR comprises:
estimating a correlation matrix of noise plus interference;
estimating a steering vector for the SOI;
determining a first basis vector using the correlation matrix and the estimated SOI steering vector;
selecting a second basis vector;
determining a target scale factor based on the target SINR and the estimated maximum output SINR;
transforming a two-dimensional vector containing the target scale factor using the first and second basis vectors; and
determining the beam weights using the transformed two-dimensional vector and the estimated correlation matrix.

8. The method of claim 7 , wherein selecting the second basis vector comprises selecting the second basis vector with the object of minimally degrading a signal-to-noise ratio (SNR) of the SOI using a Gram-Schmidt technique.

9. The method of claim 1 , wherein the multi-user detection unit is configured to recover the SOI using successive interference cancellation (SIC).

10. A system comprising:
a plurality of antenna elements;
a front end unit coupled to receive signals from the plurality of antenna elements and configured to down covert the received signals, one or more of the down converted signals comprised of a signal of interest (SOI), one or more interfering signals, and noise;
a beam determination unit configured to:
determine a maximum output SINR, and
determine beam weights to achieve a target SINR using the determined maximum output SINR;

a beamformer coupled to receive the down converted signals from the front end unit and configured to apply the beam weights to the down converted signal to generate a beamformed signal having the target SINR; and
a multi-user detection (MUD) unit couple to receive the beamformed signal and configured to recover the SOI therefrom.

11. The system of claim 10 , wherein determining the maximum output SINR comprises determining beam weights that maximize SINR.

12. The system of claim 11 , wherein determining the beam weights that maximize SINR includes using at least one of:
minimum variance distortion-less response (MVDR) beamforming;
space time adaptive processing (STAP) beamforming; or
space time frequency adaptive processing (STFAP) beamforming.

13. The system of claim 11 , wherein determining the maximum output SINR includes estimating the maximum output SINR using a closed form solution.

14. The system of claim 11 , wherein determining the maximum output SINR further comprises applying the beam weights that maximize SINR to a model of the SOI and a model of the noise plus interference to determine the maximum output SINR.

15. The system of claim 11 , wherein determining the maximum output SINR comprises:
applying the beam weights that maximize SINR to the received signal to obtain signal samples; and
determining the maximum output SINR using the obtained signal samples.

16. The system of claim 10 , wherein determining the beam weights to achieve the target SINR comprises:
estimating a correlation matrix of noise plus interference;
estimating a steering vector for the SOI;
determining a first basis vector using the correlation matrix and the estimated SOI steering vector;
selecting a second basis vector;
determining a target scale factor based on the target SINR and the estimated maximum output SINR;
transforming a two-dimensional vector containing the target scale factor using the first and second basis vectors; and
determining the beam weights using the transformed two-dimensional vector and the estimated correlation matrix.

17. The method of claim 16 , wherein selecting the second basis vector comprises selecting the second basis vector with the object of minimally degrading a signal-to-noise ratio (SNR) of the SOI using a Gram-Schmidt technique.

18. The system of claim 10 , wherein the multi-user detection unit is configured to recover the SOI using successive interference cancellation (SIC).

Assignees

• Massachusetts Inst Technology

Inventors

• Dowling Michael

Classifications

• H04B7/086 Primary

  using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming · CPC title

• H04B7/088

  using beam selection · CPC title

• H04B1/10 Primary

  Means associated with receiver for limiting or suppressing noise or interference · CPC title