# US 11,451,278 B2 · Reciprocity-based transmission

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- Number: US 11,451,278 B2
- Document ID: US11451278B2
- Status: Granted
- Kind: B2
- Application number: 17/312,562
- Filed: 2018-12-11
- Published: 2022-02-24
- Granted: 2022-09-20
- Earliest claimed: 2018-12-11
- Assignees: Telefonaktibolaget LM Ericsson (publ)
- Applicants: Telefonaktiebolaget LM Ericsson (publ)
- Inventors: Niklas Jaldén; Markus Ringström
- Web page: https://patentgrep.com/patent/US11451278B2

## CPC

- H04B 7/0617: {for beam forming}
- H04B 7/0639: {Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection}
- H04L 25/0202: {Channel estimation}
- H04B: TRANSMISSION
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

Embodiments presented herein relate to a method for reciprocity-based transmission in a radio communication network. The method is performed in a base station and may include obtaining a channel estimation of Rx quantities of a set of receive, Rx, and transmit, Tx, distribution networks, obtaining a channel estimation of Rx quantities of a set of Rx distribution networks, and performing reciprocity-based transmission with utilization of the obtained channel estimation of Rx quantities of both the set of Rx and Tx distribution network and the set of Rx distribution network, whereby channel estimation of Rx quantities of more Rx distribution networks than Tx distribution networks are utilized for the reciprocity-based transmission. A method, a base station, a wireless device, a computer programs and a computer program product for reciprocity-based beamforming in a radio communication network are also presented.

## Claims

### Claim 1

A method for reciprocity-based transmission in a radio communication network, the method being performed in a base station and comprising:
obtaining a channel estimation of receive, Rx, quantities of a set of Rx and transmit, Tx, distribution networks;
obtaining a channel estimation of Rx quantities of a set of Rx distribution networks; and
performing reciprocity-based transmission with utilization of the obtained channel estimation of Rx quantities of both the set of Rx and Tx distribution network and the set of Rx distribution network, whereby channel estimation of Rx quantities of more Rx distribution networks than Tx distribution networks are utilized for the reciprocity-based transmission, the Rx distribution network channel estimates being given larger weights than the Rx and Tx distribution network channel estimate weights.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the step of performing further comprises performing reciprocity-based beamforming.

### Claim 3 (depends on 1)

The method according to claim 1, further comprising:
obtaining information of an array structure of the set of Rx and Tx distribution networks and of an array structure of the set of Rx distribution networks, wherein the obtained information is utilized for the reciprocity-based beamforming.

### Claim 4 (depends on 1)

The method according to claim 1, wherein antenna elements of the set of Rx distribution networks are interlaced with antenna elements of the set of Rx and Tx distribution networks.

### Claim 5

A method for reciprocity-based transmission in a radio communication network, the method being performed in a wireless device and comprising:
obtaining a channel estimation of receive, Rx, quantities of a set of Rx and transmit, Tx, distribution networks;
obtaining a channel estimation of Rx quantities of a set of Rx distribution networks; and
performing reciprocity-based transmission with utilization of the obtained channel estimation of Rx quantities of both the set of Rx and Tx distribution network and the set of Rx distribution network, whereby channel estimation of Rx quantities of more Rx distribution networks than Tx distribution networks are utilized for the reciprocity-based transmission, the Rx distribution network channel estimates being given larger weights than the Rx and Tx distribution network channel estimate weights.

### Claim 6 (depends on 5)

The method according to claim 5, wherein the step of performing further comprises performing reciprocity-based beamforming.

### Claim 7 (depends on 5)

The method according to claim 5, further comprising:
obtaining information of an array structure of the set of Rx and Tx distribution networks and of an array structure of the set of Rx distribution networks, wherein the obtained information is utilized for the reciprocity-based beamforming.

### Claim 8 (depends on 5)

The method according to claim 5, wherein antenna elements of the set of Rx distribution networks are interlaced with antenna elements of the set of Rx and Tx distribution networks.

### Claim 9

A base station for reciprocity-based transmission in a radio communication network, the base station comprising:
a processing circuitry; and
a computer program product storing instructions that, when executed by the processing circuitry, causes the base station to:
obtain a channel estimation of receive, Rx, quantities of a set of Rx and transmit, Tx, distribution networks;
obtain a channel estimation of Rx quantities of a set of Rx distribution networks; and
perform reciprocity-based transmission with utilization of the obtained channel estimation of Rx quantities of both the set of Rx and Tx distribution network and the set of Rx distribution network, whereby channel estimation of Rx quantities of more Rx distribution networks than Tx distribution networks are utilized for the reciprocity-based transmission, the Rx distribution network channel estimates being given larger weights than the Rx and Tx distribution network channel estimate weights.

### Claim 10 (depends on 9)

The base station according to claim 9, wherein the reciprocity-based transmission further comprises reciprocity-based beamforming.

### Claim 11 (depends on 9)

The base station according to claim 9, wherein the base station further is caused to:
obtain information of an array structure of the set of Rx and Tx distribution networks and of an array structure of the set of Rx distribution networks, wherein the obtained information is utilized for the reciprocity-based beamforming.

### Claim 12 (depends on 9)

The base station according to claim 9, wherein antenna elements of the set of Rx distribution networks are interlaced with antenna elements of the set of Rx and Tx distribution networks.

### Claim 13

A wireless device for reciprocity-based transmission in a radio communication network, the wireless device comprising:
a processing circuitry; and
a computer program product storing instructions that, when executed by the processing circuitry, causes the wireless device to:
obtain a channel estimation of receive, Rx, quantities of a set of Rx and transmit, Tx, distribution networks;
obtain a channel estimation of Rx quantities of a set of Rx distribution networks; and
perform reciprocity-based transmission with utilization of the obtained channel estimation of Rx quantities of both the set of Rx and Tx distribution network and the set of Rx distribution network, whereby channel estimation of Rx quantities of more Rx distribution networks than Tx distribution networks are utilized for the reciprocity-based transmission, the Rx distribution network channel estimates being given larger weights than Rx and Tx distribution network channel estimate weights.

### Claim 14 (depends on 13)

The wireless device according to claim 13, wherein the reciprocity-based transmission comprises reciprocity-based beamforming.

### Claim 15 (depends on 13)

The wireless device according to claim 13, wherein the wireless device further is caused to:
obtain information of an array structure of the set of Rx and Tx distribution networks and of an array structure of the set of Rx distribution networks, wherein the obtained information is utilized for the reciprocity-based beamforming.

### Claim 16 (depends on 13)

The wireless device according to claim 13, wherein antenna elements of the set of Rx distribution networks are interlaced with antenna elements of the set of Rx and Tx distribution networks.