# US 10,374,670 B2 · Port-to-beam precoding to enable codebook based MU-MIMO operation in active antenna systems

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- Number: US 10,374,670 B2
- Document ID: US10374670B2
- Status: Granted
- Kind: B2
- Application number: 16/128,864
- Filed: 2018-09-12
- Published: 2019-03-21
- Granted: 2019-08-06
- Earliest claimed: 2017-09-15
- Assignees: Blue Danube Systems, Inc.
- Applicants: Blue Danube Systems, Inc.
- Inventors: Dilip Bethanabhotla; Chris Tsun Kit Ng; Mihai Banu
- Web page: https://patentgrep.com/patent/US10374670B2

## CPC

- H04B 7/0456: Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
- H04B 7/0452: Multi-user MIMO systems
- H04B 7/0608: {Antenna selection according to transmission parameters}
- H04B 7/0617: {for beam forming}
- H04W 88/085: {Access point devices with remote components}
- H04B: TRANSMISSION
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

A method for communicating with a plurality of communication devices (UEs) using a phased array antenna system including an array of antenna elements, the method involving: receiving a plurality of port signal streams, wherein the plurality of port signal streams was obtained by precoding a plurality of data streams, each data stream of the plurality of data streams intended for a different corresponding UE; and within the phased array antenna system, processing the plurality of port signal streams to (1) undo the precoding that was performed on the plurality of data streams, and (2) generate via the array of antenna elements a plurality of transmit beams, wherein each transmit beam is directed towards a corresponding different UE among the plurality of UEs and carries a corresponding transmit signal that is derived exclusively from the data stream among the plurality of data streams that is intended for that UE.

## Claims

### Claim 1

A method for communicating with a plurality of communication devices (UEs) using a phased array antenna system including an array of antenna elements, said method comprising:
receiving a plurality of port signal streams, wherein the plurality of port signal streams was obtained by precoding a plurality of data streams, each data stream of the plurality of data streams intended for a different corresponding UE among the plurality of UEs; and
within the phased array antenna system, processing the plurality of port signal streams to (1) undo the preceding that was performed on the plurality of data streams, and (2) generate via the array of antenna elements a plurality of transmit beams, wherein each transmit beam is directed towards a corresponding different UE among the plurality of UEs and carries a corresponding transmit signal that is derived exclusively from the data stream among the plurality of data streams that is intended for that UE.

### Claim 2 (depends on 1)

The method of claim 1, wherein precoding involves applying a layer-to-port preceding matrix to the plurality of data streams to yield the plurality of port signal streams among which each port signal stream is a linear combination of the plurality of data streams.

### Claim 3 (depends on 2)

The method of claim 2, wherein processing the plurality of port signal streams effectively applies a port-to-beam precoding matrix to the plurality of port signal streams, wherein the port-to-beam matrix and the layer-to-port matrix when multiplied together generates a diagonal matrix.

### Claim 4 (depends on 3)

The method of claim 3, wherein the diagonal matrix is an identity matrix.

### Claim 5 (depends on 3)

The method of claim 3, wherein the port-to-beam precoding matrix is applied to the plurality of port signal streams in a digital domain.

### Claim 6 (depends on 3)

The method of claim 3, wherein the port-to-beam preceding matrix is applied to the plurality of port signal streams in an analog domain.

### Claim 7 (depends on 6)

The method of claim 6, wherein processing involves applying beamforming weights to the phased array antenna system to generate the plurality of transmit beams.

### Claim 8 (depends on 2)

The method of claim 2, wherein processing involves converting the plurality of port signal streams from digital to analog to generate a plurality of analog signal streams; and in the analog domain applying beamforming weights to the phased array antenna system to generate the plurality of transmit beams.

### Claim 9 (depends on 8)

The method of claim 8, wherein the beamforming weights also cause the phased array antenna system to undo the precoding that was performed on the plurality of data streams.

### Claim 10 (depends on 9)

The method of claim 9, wherein the beamforming weights cause the phased array antenna system to effectively apply a port-to-beam precoding matrix to the plurality of analog signal streams, wherein the port-to-beam matrix and the layer-to-port matrix when multiplied together generates a diagonal matrix.

### Claim 11 (depends on 3)

The method of claim 3, wherein the port-to-beam precoding matrix is constructed from N precoding vectors that are mutually orthogonal, and wherein N is an integer equal to the number of data streams within the plurality of data streams.

### Claim 12 (depends on 11)

The method of claim 11, wherein the N precoding vectors are selected from a MU-MIMO codebook.

### Claim 13 (depends on 3)

The method of claim 3, wherein the layer-to-port precoding matrix is a non-diagonal matrix, the port-to-beam precoding matrix is a non-diagonal matrix, and the product of the layer-to-port precoding matrix and the port-to-beam precoding matrix is a diagonal matrix.