# US 2019/0059094 A1 · Device-to-device synchronization

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- Number: US 2019/0059094 A1
- Document ID: US20190059094A1
- Status: Published application
- Kind: A1
- Application number: 16/167,682
- Filed: 2018-10-23
- Published: 2019-02-21
- Earliest claimed: 2014-03-19
- Assignees: InterDigital Patent Holdings, Inc.
- Applicants: Interdigital Patent Holdings, Inc.
- Inventors: Samian Kaur; Diana Pani; Yuxin Zhao; Benoit Pelletier
- Web page: https://patentgrep.com/patent/US20190059094A1

## CPC

- H04W 72/121: for groups of terminals or users
- H04W 52/383: {power control in peer-to-peer links}
- H04W 56/002: {Mutual synchronization}
- H04W 72/02: Selection of wireless resources by user or terminal
- H04W 72/12: Wireless traffic scheduling
- H04W 76/14: Direct-mode setup
- H04W 76/18: Management of setup rejection or failure
- H04W 76/19: Connection re-establishment
- H04W 76/23: Manipulation of direct-mode connections
- 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 transmit receive unit (WTRU) may be operated in a first scheduling mode for device-to-device communication. In the first scheduling mode, a network entity may schedule resources to be used by the WTRU for device-to-device communications. The WTRU may detect that a radio link failure (RLF) timer is running or has been started. The WTRU may switch from the first scheduling mode for device-to-device communication to a second scheduling mode for device-to-device communication in response to detecting that the radio link failure timer is running or has been started. In the second scheduling mode, the WTRU may select a resource from a resource pool for the WTRU to use for one or more device-to-device communications.

## Claims

### Claim 1

A method performed by a wireless transmit/receive unit (WTRU), the method comprising:
determining that the WTRU has device-to-device data to transmit while in a RRC_IDLE mode;
initiating a request to a network, wherein the request relates to obtaining resources for device-to-device communication;
detecting that a time period associated with the request has expired;
operating in a second scheduling mode for device-to-device communication in response to detecting that the time period has expired, wherein in the second scheduling mode the WTRU autonomously selects a resource from a resource pool for the WTRU to transmit the device-to-device data.

### Claim 2 (depends on 1)

The method of claim 1, further comprising using a timer to determine when the time period has expired.

### Claim 3 (depends on 2)

The method of claim 2, wherein the timer is started in response to initiating the request to the network.

### Claim 4 (depends on 1)

The method of claim 1, further comprising ceasing operation of the WTRU in the second scheduling mode upon being scheduled by the network with device-to-device communication resources.

### Claim 5 (depends on 4)

The method of claim 4, further comprising operating in a first scheduling mode for device-to-device communication in response to being scheduled by the network with device-to-device communication resources.

### Claim 6 (depends on 1)

The method of claim 1, further comprising ceasing operation of the WTRU in the second scheduling mode upon establishing a radio resource control (RRC) connection with the network.

### Claim 7 (depends on 1)

The method of claim 1, wherein operating in the second scheduling mode comprises operating in the second scheduling mode using fixed power control.

### Claim 8 (depends on 1)

The method of claim 1, wherein the resource pool is configured by the network via broadcast signaling.

### Claim 9

A wireless transmit/receive unit (WTRU) comprising:
a processor configured to:
determine that the WTRU has device-to-device data to transmit while in a RRC_IDLE mode;
initiate a request to a network, wherein the request relates to obtaining resources for device-to-device communication;
detect that a time period associated with the request has expired;
operate in a second scheduling mode for device-to-device communication in response to detecting that the time period has expired, wherein in the second scheduling mode the WTRU autonomously selects a resource from a resource pool for the WTRU to transmit the device-to-device data.

### Claim 10 (depends on 9)

The WTRU of claim 9, wherein the processor is further configured to use a timer to determine when the time period has expired.

### Claim 11 (depends on 10)

The WTRU of claim 10, wherein the timer is started in response to initiating the request to the network.

### Claim 12 (depends on 9)

The WTRU of claim 9, wherein the processor is further configured to cease operation of the WTRU in the second scheduling mode upon being scheduled by the network with device-to-device communication resources.

### Claim 13 (depends on 12)

The WTRU of claim 12, further comprising operating in a first scheduling mode for device-to-device communication in response to being scheduled by the network with device-to-device communication resources.

### Claim 14 (depends on 9)

The WTRU of claim 9, wherein the processor is further configured to cease operation of the WTRU in the second scheduling mode upon establishing a radio resource control (RRC) connection with the network.

### Claim 15 (depends on 9)

The WTRU of claim 9, wherein the processor is configured to operate in the second scheduling mode using fixed power control.

### Claim 16 (depends on 9)

The WTRU of claim 9, wherein the resource pool is configured by the network via broadcast signaling.