# US 10,375,661 B2 · Method for transmitting synchronization signal for D2D communication in wireless communication system and apparatus therefor

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- Number: US 10,375,661 B2
- Document ID: US10375661B2
- Status: Granted
- Kind: B2
- Application number: 15/304,470
- Filed: 2015-04-24
- Published: 2017-02-09
- Granted: 2019-08-06
- Earliest claimed: 2014-04-24
- Assignees: LG Electronics Inc.
- Applicants: LG Electronics Inc.
- Inventors: Seungmin Lee; Hanbyul Seo; Kijun Kim
- Web page: https://patentgrep.com/patent/US10375661B2

## CPC

- H04W 56/0015: {one node acting as a reference for the others}
- H04J 11/00: Orthogonal multiplex systems, {e.g. using WALSH codes}(H04J13/00 takes precedence)
- H04L 1/1812: Hybrid protocols; Hybrid automatic repeat request [HARQ]
- H04L 5/0055: {Physical resource allocation for ACK/NACK (for physical mapping arrangements in ARQ protocols H04L1/1861)}
- H04L 5/0073: {Allocation arrangements that take into account other cell interferences}
- H04L 12/2854: {Wide area networks, e.g. public data networks}
- H04W 56/0025: {synchronizing potentially movable access points}
- H04W 72/04: Wireless resource allocation
- H04W 76/14: Direct-mode setup
- H04J 2011/0096: {Network synchronisation}
- H04L 1/1671: {the supervisory signal being transmitted together with control information}
- H04L 1/1896: {ARQ related signaling}
- H04L 5/0007: {the frequencies being orthogonal, e.g. OFDM(A) or DMT}
- H04L 5/1469: {using time-sharing}
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

The present invention relates to a method and an apparatus for transmitting a device-to-device (D2D) synchronization signal of a first terminal in a wireless communication system. Specifically, the method comprises the steps of: receiving a radio resource setting for D2D communication; and transmitting a D2D synchronization signal to a second radio resource which corresponds to a specific index, other than a first radio resource, from among a plurality of radio resource setting-based D2D radio resources, wherein the first radio resource is defined to be used for wide area network (WAN) based communication.

## Claims

### Claim 1

A method for receiving a device-to-device (D2D) synchronization signal by a D2D terminal in a wireless communication system, the method comprising:
receiving information related to radio resource configuration for D2D communication,
wherein the information related to radio resource configuration comprises information for receiving the D2D synchronization signal;
receiving the D2D synchronization signal based on the information related to radio resource configuration;
deriving a subframe index through which the D2D synchronization signal is transmitted from a sequence repetition pattern of the D2D synchronization signal; and
deriving a root sequence index of the D2D synchronization signal from the subframe index.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the subframe index is obtained by applying a predetermined offset to an index based on an uplink-downlink configuration for Wide Area Network (WAN) based communication.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the subframe index is predefined, and
wherein the D2D synchronization signal indicates a position of a window having a predetermined period in which the D2D synchronization signal is received, in a radio resource corresponding to the subframe index.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the D2D synchronization signal includes information indicating the number of relays for D2D communication.

### Claim 5 (depends on 4)

The method according to claim 4,
wherein the D2D synchronization signal includes information of a hop count and a system frame number.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the D2D synchronization signal is a sidelink synchronization signal.

### Claim 7

A device-to-device (D2D) terminal for receiving a D2D synchronization signal in a wireless communication system, the D2D terminal comprising:
a radio frequency (RF) unit; and
a processor,
wherein the processor is configured to:
control the RF unit to receive information related to radio resource configuration for D2D communication,
wherein the information related to radio resource configuration comprises information for receiving the D2D synchronization signal;
control the RF unit to receive the D2D synchronization signal based on the information related to radio resource configuration;
derive a subframe index through which the D2D synchronization signal is transmitted from a sequence repetition pattern of the D2D synchronization signal; and
derive a root sequence index of the D2D synchronization signal from the subframe index.

### Claim 8 (depends on 7)

The D2D terminal according to claim 7, wherein the subframe index is obtained by applying a predetermined offset to an index based on an uplink-downlink configuration for Wide Area Network (WAN) based communication.