Method and apparatus for device-to-device communication in wireless communication system

• US 9,699,749 B2
• Filed: 12/20/2013
• Issued: 07/04/2017
• Est. Priority Date: 12/21/2012
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Kim, Hakseong, Lee, Seungmin, Seo, Hanbyul, Chae, Hyukjin
• Primary Examiner(s): Wong, Warner
• Application Number:
  US14/648,784
• Publication Number:
  US 20150319724A1
• Time in Patent Office: 1,292 Days
• CPC Class Codes: H04L 27/261 Details of reference signals
• CPC Class Codes: H04L 27/2675 Pilot or known symbols
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 65/10 Architectures or entities
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 56/0015 one node acting as a reference for the others
• CPC Class Codes: H04W 56/0025 synchronizing potentially movable access points
• CPC Class Codes: H04W 72/20 Control channels or signalling for resource management
• CPC Class Codes: H04W 8/005 Discovery of network devices, e.g. terminals
• CPC Class Codes: H04W 88/04 adapted for relaying to or from another terminal or user

Abstract

One embodiment of the present invention is a device-to-device (D2D) communication method. According to said method, a first terminal performs D2D communication with a second terminal in a wireless communication system, and comprises the steps of: receiving a first signal from the second terminal; and transmitting a second signal based on the received first signal to a third terminal. The first signal and the second signal are used in acquiring synchronization related to the D2D communication in each of the first terminal and the third terminal.

Claims

1. A method for performing device-to-device (D2D) communication with a second user equipment (UE) by a first UE in a wireless communication system, the method comprising:

receiving a first signal from the second UE; and

delivering a second signal based on the received first signal to a third UE,

wherein the first and second signals are used for synchronization acquisition related to D2D communication in each of the first UE and the third UE,

wherein the first signal comprises a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) received from a serving cell of the second UE,

wherein a sequence for the PSS is mapped to 62/x subcarriers excluding a direct current (DC) subcarrier,

wherein a sequence for the SSS is mapped to 62/y subcarriers excluding the DC subcarrier,

wherein x and y are values selected from divisors of 62.

2. The method according to claim 1, wherein the first UE is out of coverage of a cell to which the second UE belongs.

3. The method according to claim 1, wherein the first signal and the second signal are transmitted using different time/frequency resources.

4. The method according to claim 1, wherein the first signal is transmitted in time/frequency resources which do not overlap with time/frequency resources in which a PSS and a SSS are transmitted by a serving cell of the second UE.

5. The method according to claim 1, wherein the first UE delivers the same second signal as the received first signal to the third UE via time-frequency resources different from time-frequency resources used to receive the first signal.

6. The method according to claim 1, wherein the first UE performs D2D communication only in a resource block in which receive power of the first signal is equal to or less than a predetermined value.

7. The method according to claim 1, wherein the first UE terminates D2D communication during N frames after receiving the first signal.

8. The method according to claim 1, wherein the first UE determines transmit power of D2D communication based on receive power of the first signal.

9. The method according to claim 8, wherein the transmit power of D2D communication is inversely proportional to the receive power of the first signal.

10. The method according to claim 1, wherein the first UE uses a downlink frequency band for D2D communication if receive power of the first signal is equal to or less than a predetermined value.

11. A user equipment (UE) apparatus for performing device-to-device (D2D) communication with a second UE in a wireless communication system, the first UE apparatus comprising:

a reception module; and

a processor,

wherein the processor receives a first signal from the second UE and delivers a second signal based on the received first signal to a third UE, and

wherein the first and second signals are used for synchronization acquisition related to D2D communication in each of the first UE and the third UE,

wherein the first signal comprises a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) received from serving cell of the second UE,

wherein a sequence for PSS is mapped to 62/x subcarriers excluding a direct current (DC) subcarrier,

wherein a sequence for SSS is mapped to 62/y subcarriers excluding the DC subcarrier, wherein x and y are values selected from divisors of 62.