BEAMFORMER PHASE OPTIMIZATION FOR A MULTI-LAYER MIMO SYSTEM AUGMENTED BY RADIO DISTRIBUTION NETWORK

• US 20140376671A1
• Filed: 07/01/2014
• Published: 12/25/2014
• Est. Priority Date: 05/29/2012
• Status: Active Grant

• Current Assignee: Magnolia Broadband Incorporated
• Original Assignee: Magnolia Broadband Incorporated
• Inventors: ABREU, Eduardo, HAREL, Haim, KLUDT, Kenneth, CHEN, Phil F., WANG, Sherwin J.
• Granted Patent: US 9,344,168 B2
• Time in Patent Office: Days
• US Class Current: 375/347
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0456 Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
• 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 7/088 using beam selection

Abstract

A system for selecting optimal phase combinations for RF beamformers in a MIMO hybrid receiving systems augmented by RF Distribution Network. The system addresses the issue of providing beamforming gains for a plurality of layers using one common set of weights for each beamformer. The specification may be based on channel estimation of all layers as viewed by all receiving antennas, and maximizing metrics that capture the total received power.

Claims

1. A multiple inputs multiple outputs (MIMO) receiving system having number N channels, comprising:

a radio distributed network (RDN) having number N beamformers, each having number K_N antennas;

at least one phase shifter associated with one or more of the N beamformers,

wherein the MIMO receiving system is configured to;

(a) select one phase that optimizes performance of multiple layers, via channel estimation of each layer as seen by each receiving antenna, and (b) maximize a total received power from all transmitted signals.

2. The system according to claim 1, wherein the MIMO receiving system optimizes a beamformer phase by:

performing channel estimation of each layer from each receiving antenna, selecting metrics that capture the combined received power, and using relative phase setting between various antennas to calculate a set that maximizes that metrics.

3. The system according to claim 1, wherein phase optimization is carried out by:

calculating channel functions h_i,j,k from each one of the N transmit antenna j, j=1,2 . . . NM, to each one of the K_N receive antenna i, i=1,2 . . . NK_N, at frequency k, k=1,2 . . . L, at the baseband module using channel estimation;

selecting phases, wherein

4. The system according to claim 1, wherein phase optimization is carried out by:

adjusting the antennas one by one recursively, wherein φ

₁ is set to zero, and only contributions from and h_1,j,k and h_2,j,k are used to calculate φ

₂;

defining a combined channel s_2,j,k and a channel power p_2,j,k for the first two antennas as;

p_2,j,k=[abs(s_2,j,k)]², j=1,2 . . . N, k=1,2 . . . L; and

choosing φ

₂∈

S that maximizes

5. The system according to claim 4, wherein the optimization of the phase of the beamformer is calculated wherein once φ

<sub>i−

1</sub> has been determined, φ

_i is calculated.

6. The system according to claim 5, wherein:

7. The system according to claim 5, wherein: