# US 10,873,921 B2 · Unlicensed cell downlink signal synchronization

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- Number: US 10,873,921 B2
- Document ID: US10873921B2
- Status: Granted
- Kind: B2
- Application number: 16/185,456
- Filed: 2018-11-09
- Published: 2019-03-14
- Granted: 2020-12-22
- Earliest claimed: 2015-09-14
- Assignees: Ofinno, LLC
- Applicants: Ofinno Technologies, LLC
- Inventors: Esmael Dinan
- Web page: https://patentgrep.com/patent/US10873921B2

## CPC

- H04W 56/0015: {one node acting as a reference for the others}
- H04W 4/08: User group management
- H04W 8/005: {Discovery of network devices, e.g. terminals}
- H04W 16/14: Spectrum sharing arrangements {between different networks}
- H04W 48/12: using downlink control channel
- H04W 72/23: in the downlink direction of a wireless link, i.e. towards a terminal
- H04W 74/0808: using carrier sensing, e.g. carrier sense multiple access [CSMA]
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

A wireless device receives at least one control message comprising configuration parameters of a first unlicensed cell and a second unlicensed cell. The wireless device receives, via the first unlicensed cell, a first signal comprising a first downlink synchronization signal. The wireless device receives, via the second unlicensed cell, a second signal comprising a second downlink synchronization signal. The wireless device synchronizes a first downlink signal timing with the first unlicensed cell based on the second signal received via the second unlicensed cell. The wireless device synchronizes a second downlink signal timing with the second unlicensed cell based on the first signal received via the first unlicensed cell.

## Claims

### Claim 1

A wireless device comprising:
one or more processors; and
memory storing instructions that, when executed by the one or more processors, cause the wireless device to:
receive configuration parameters of a timing advance group (TAG) comprising a first unlicensed cell and a second unlicensed cell;
receive, via the first unlicensed cell of the TAG, a first signal comprising a first downlink synchronization signal;
receive, via the second unlicensed cell of the TAG, a second signal comprising a second downlink synchronization signal;
synchronize a first downlink signal timing with the first unlicensed cell based on both of the first signal received via the first unlicensed cell of the TAG and the second signal received via the second unlicensed cell of the TAG; and
synchronize a second downlink signal timing with the second unlicensed cell based on both of the first signal received via the first unlicensed cell of the TAG and the second signal received via the second unlicensed cell of the TAG.

### Claim 2 (depends on 1)

The wireless device of claim 1, wherein the first signal is received in a plurality of subframes.

### Claim 3 (depends on 1)

The wireless device of claim 1, wherein the second signal is received in a plurality of subframes.

### Claim 4 (depends on 1)

The wireless device of claim 1, wherein the second signal comprises a discovery signal.

### Claim 5 (depends on 1)

The wireless device of claim 1, wherein the second signal comprises a reference signal.

### Claim 6 (depends on 1)

The wireless device of claim 1, wherein a cell group is configured at least for downlink synchronization.

### Claim 7 (depends on 1)

The wireless device of claim 1, wherein at least one of the first unlicensed cell and the second unlicensed cell is a licensed assisted access cell.

### Claim 8 (depends on 1)

The wireless device of claim 1, wherein a transmission of the second signal is subject to a listen before talk mechanism.

### Claim 9

A method comprising:
receiving, by a wireless device, configuration parameters of a timing advance group (TAG) comprising a first unlicensed cell and a second unlicensed cell;
receiving, via the first unlicensed cell of the TAG, a first signal comprising a first downlink synchronization signal;
receiving, via the second unlicensed cell of the TAG, a second signal comprising a second downlink synchronization signal;
synchronizing a first downlink signal timing with the first unlicensed cell based on both of the first signal received via the first unlicensed cell of the TAG and the second signal received via the second unlicensed cell of the TAG; and
synchronizing a second downlink signal timing with the second unlicensed cell based on both of the first signal received via the first unlicensed cell of the TAG and the second signal received via the second unlicensed cell of the TAG.

### Claim 10 (depends on 9)

The method of claim 9, wherein the first signal is received in a plurality of subframes.

### Claim 11 (depends on 9)

The method of claim 9, wherein the second signal is received in a plurality of subframes.

### Claim 12 (depends on 9)

The method of claim 9, wherein the second signal comprises a discovery signal.

### Claim 13 (depends on 9)

The method of claim 9, wherein the second signal comprises a reference signal.

### Claim 14 (depends on 9)

The method of claim 9, wherein a cell group is configured at least for downlink synchronization.

### Claim 15 (depends on 9)

The method of claim 9, wherein at least one of the first unlicensed cell and the second unlicensed cell is a licensed assisted access cell.

### Claim 16 (depends on 9)

The method of claim 9, wherein a transmission of the second signal is subject to a listen before talk mechanism.