Method and apparatus for synchronization for device-to-device communication

An apparatus for synchronization for a device-to-device communication, the apparatus comprising:

• a receiver configured to receive and detect a synchronization signal from at least one adjacent device;
• a transmitter configured to transmit a synchronization signal in response to a synchronization phase value reaching a predetermined maximum value;
• and
• a processor configured to:
• that instantly adjusts a synchronization phase value according to a time point when a synchronization signal is received,
• in response to detecting the at least one synchronization signal from at least one adjacent device in a connected state, accumulatively store at least one phase adjustment value according to a time point when at least one synchronization signal is received as soon as the synchronization signal is received from an adjacent device in an unconnected state, and
• adjusts the synchronization phase value according to the stored at least one phase adjustment value in response to a transition of the device from the connected state to the unconnected state.

A wireless communication system for synchronization for a device-to-device communication, the system comprising:

• a first device comprising:
• a receiver configured to receive and detect a synchronization signal from at least one adjacent device;
• a transmitter configured to transmit a synchronization signal in response to a synchronization phase value reaching a predetermined maximum value;
• and
• a processor configured to:
• that instantly adjusts a synchronization phase value according to a time point when a synchronization signal is received,
• in response to detecting the at least one synchronization signal from at least one adjacent device in a connected state, accumulatively store at least one phase adjustment value according to a time point when at least one synchronization signal is received as soon as the synchronization signal is received from an adjacent device in an unconnected state, and
• adjusts the synchronization phase value according to the stored at least one phase adjustment value in response to a transition of the device from the connected state to the unconnected state.