Setting radio frequency (RF) beamformer antenna weights per data-stream in a multiple-input-multiple-output (MIMO) system

• US 8,861,635 B2
• Filed: 10/28/2013
• Issued: 10/14/2014
• Est. Priority Date: 05/29/2012
• Status: Expired due to Fees

• Current Assignee: Magnolia Broadband Incorporated
• Original Assignee: Magnolia Broadband Incorporated
• Inventors: Wang, Sherwin J., Chen, Phil F.
• Primary Examiner(s): NEFF, MICHAEL R
• Application Number:
  US14/065,182
• Publication Number:
  US 20140051377A1
• Time in Patent Office: 351 Days
• Field of Search: 375/267, 375/260, 375/259
• US Class Current: 375/267
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/086 using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming
• CPC Class Codes: H04B 7/0874 using subgroups of receive antennas

Abstract

A system and a closed form method of optimizing a set of receive beamformers'"'"' weights, each feeding one of N multi-layer MIMO receiving system wherein the beamformers have a pool of M receive antennas wherein M is greater than N. Each beamformer is tuned to optimize one data stream, where selection of antennas per beamformer may be done out of a pool of antennas, and mapping of a given beamformer to a data stream is optimized per certain performance metrics.

Claims

1. A system comprising:

a number M receive antennas configured to receive a number N transmitted signals associated with respective data streams;

a number N beamformers connected to the M receive antennas, configured to combine signals coming from the antennas, wherein M is greater than N, and wherein M and N are integers

a baseband module coupled to the N beamformers configured to apply at least one multiple input multiple output (MIMO) receiving scheme to the combined signals; and

a control module configured to;

assign each of K receive antennas in each beamformer with a phase/gain that maximizes a received power of at least one of the data streams;

wherein K is an integer;

compare overall performance of mapping configuration which map between the beamformers and the data streams; and

select the mapping configuration which results in higher signal to interference plus noise (SINR) measured at the baseband module, wherein the received power is computed via pre-coding weight and channel estimation through each of the K receive antennas.

2. The system according to claim 1, further comprising a switch matrix configured to swap at least some of the receive antenna connections amongst the beamformers, wherein the beamformers consecutively select a desired combination of K*N antennas from the set antennas wherein each consecutive selection is carried out on the antennas that were not yet selected.

3. The system according to claim 1, wherein the phase settings for the receive antennas is computed for all different beamformer-data stream mapping configurations.

4. The system according to claim 1, wherein the phase/gain settings are carried out at the base band module.

5. A method comprising:

receiving a number N transmitted signals associated with respective data streams, via M receive antennas connected to a number N beamformers, wherein M is greater than N, and wherein M and N are integers

assigning each of K receive antennas in each beamformer with a phase/gain that maximizes a received power of at least one of the data streams, wherein K is an integer;

wherein the received power is computed via a known pre-coding weight, and channel estimation through each of the K receiving antennas;

comparing overall performance of mapping configuration which map between the beamformers and the data streams; and

selecting the mapping configuration which results in higher signal to interference plus noise (SINR) measured at the baseband module.

6. The method according to claim 5, further comprising swapping at least some of the receive antenna connections amongst the beamformers, wherein the beamformers consecutively select a desired combination of K*N antennas from the set antennas wherein each consecutive selection is carried out on the antennas that were not yet selected.

7. The method according to claim 6, wherein at least one different phase/gain settings is computed for at least one specific beamformer-data stream mapping configuration.

8. The method according to claim 5, wherein a beamformer-data stream mapping configuration is selected to maximize the total receive power of all data streams;

the phase/gain settings of the selected configuration have the maximum Σ

σ

_i² among all the configurations;

σ

_i is the singular value of transmission matrix;

Q*H*W wherein Q denotes phase/gain setting, H denotes a channel matrix, and W denotes pre-coding weight.

9. The method according to claim 5, wherein a beamformer-data stream mapping configuration is selected to have a most uniform channel gain for all the data streams, wherein the phase setting of the selected configuration has a minimum cond(Q*H*W) among all the configurations, wherein cond(Q*H*W) indicates the condition of Matrix Q*H*W, wherein Q denotes phase setting, H denotes a channel matrix, and W denotes pre-coding weight.

10. The method according to claim 5, wherein a pool of beamformer-data stream mapping configurations having relative uniform channel gains for all data streams are selected, wherein the configuration with cond(Q*H*W) below a threshold results in a relative uniform channel gains for all data streams, wherein cond(Q*H*W) indicates the condition of Matrix Q*H*W, wherein Q denotes phase setting, H denotes a channel matrix, and W denotes pre-coding weight.

11. The method according to claim 10, wherein a beamformer-data stream mapping configuration is selected with the maximum Σ

σ

_i² for optimizing the receiving system;

wherein σ

_i is the singular value of transmission matrix;

Q*H*W wherein Q denotes phase/gain setting, H denotes a channel matrix, and W denotes pre-coding weight.

12. The method according to claim 5, wherein each receive antenna is connected to any beamformer, wherein a first beamformer selects any desired combination of up to K antennas from the set of M (=K*N) ones, and a next beamformer selects any up to K ones from what is left, till all N beamformers are addressed, wherein said combinations'"'"' performance is compared and selected using performance metrics.