Abstract: A method and an apparatus for synchronization for Device-to-Device (D2D) communication in unlicensed frequency bands are provided. The method includes determining whether a signal is detected during a preset time period within a synchronization period, after transmitting a synchronization signal during the synchronization period for the D2D communication, when it is determined that the D2D communication is to be performed, and starting the time period for the D2D communication and performing the D2D communication during the time period for the D2D communication, when it is determined that the signal is not detected.

Abstract: In order to generate multiple-access signals, each transmitter transmits information by using all or a part of channel resources. The signal of each transmitter is mapped to an OFDM time-frequency resource space as a trellis modulation path. A mobile communication system maps trellis modulation paths of a plurality of transmitters to the same resource space. In order to effectively detect and distinguish signals of a plurality of transmitters transmitted through the same channel resource space, a receiver uses a message passing method between symbols and a path connection method. The receiver uses a state space expansion method, a backward pre-decoding method, and a successive interference cancellation method to more efficiently reconstruct a discovery signal.

Abstract: An apparatus is configured to perform a method for performing distributed scheduling by a reception device configuring a target link corresponding to one of a plurality of links in a network in which the plurality of links for device to device communication exist. The method includes adding up resource allocation demand amounts included in resource information broadcasted by a counterpart device configuring the target link and one or more adjacent transmission devices by a preset Resource Unit (RU), and adjusting self resource information in consideration of resource position information included in the broadcasted resource information and the added resource allocation demand amount and transmitting the adjusted self resource information to the counterpart transmission device.

Abstract: A method and apparatus for traffic safety are provided using vehicle driving-related information obtained on the basis of a transmission/reception beam pair of a road side unit (RSU) and a vehicle on-board unit (OBU), thereby reducing a probability that vehicle collisions occur where visual fields may be obscured. The method includes setting a path from a current location of the electronic device to a destination, and transmitting a message indicating an emergency situation to other devices located on the path while moving to the destination. The method further includes determining a transmission/reception beam pair of the electronic device and a road apparatus, using a reference signal received from the road apparatus, transmitting a signal including information for the transmission/reception beam pair to the road apparatus, and receiving, from the road apparatus, a message warning that the electronic device and another neighboring electronic device are approaching each other.

Abstract: A device and a method for performing Device to Device (D2D) communication in a wireless communication system are provided. The method includes transmitting information on a self-frequency band selected from all frequency bands for the D2D communication, to the second mobile station, receiving information on a counterpart-frequency band selected for the D2D communication, from the second mobile station, determining transmission and reception frequency bands to be used for the D2D communication, based on the information on the self-frequency band and the information on the counterpart-frequency band, transmitting data to the second mobile station in the determined transmission frequency band, and receiving data from the second mobile station in the determined reception frequency band.

Abstract: A method and an apparatus for performing synchronization by a first device in a Device-to-Device (D2D) network are provided. The method includes detecting a synchronization signal from at least one second device during one period, determining a phase adjustment value depending on a number of synchronization signals, which have been detected from the at least one second device during the one period, adjusting a phase value of a first device using the phase adjustment value, and transmitting a synchronization signal if the phase value of the first device reaches a predetermined specific value.

Abstract: A method and an apparatus for synchronization for a device-to-device communication are disclosed. The method includes: instantly adjusting a synchronization phase value according to a time point when a synchronization signal is received, as soon as a device receives the synchronization signal from an adjacent device in an unconnected state; accumulatively storing at least one phase adjustment value according to a time point when at least one synchronization signal is received, whenever the device receives the at least one synchronization signal from at least one adjacent device in a connected state; and adjusting the synchronization phase value according to the stored at least one phase adjustment value when the device transitions from the connected state to the unconnected state.

Abstract: A method and apparatus for performing a state transition for Device to Device (D2D) communication are provided. The method includes determining whether D2D initiation is required, while a terminal is operating in a first or a second state defined by EPS (Enhanced Packet System) Mobility Management (EMM)-Deregistered and EPS Connection Management (ECM)-IDLE at a Non-Access Stratum (NAS) layer and Radio Resource Control (RRC)-IDLE. If the D2D initiation is required, the method includes transitioning to a third state defined by EMM-Registered and ECM/RRC-Connected and performing the D2D initiation through a mobile communication network. If a deactivation condition is satisfied or a D2D state update is completed in the third state, the method includes transitioning to a fourth state defined by EMM-Registered and ECM/RRC-IDLE, and if a state update or scheduling for D2D communication is required in the fourth state, the method includes transitioning to the third state.

Abstract: The present disclosure relates to a communication method and system for converging a fifth generation (5G) communication system for supporting higher data rates beyond a fourth generation (4G) system with a technology for Internet of Things (IoT). The present disclosure applies to intelligent services based on 5G communications technology and IoT related technology, such as a smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, and security and safety services. A method for managing resources for Device to Device (D2D) communication includes: establishing a radio connection with an evolved NodeB (eNB); receiving allocated resources for D2D communication from the eNB through the radio connection; performing the D2D communication by using the allocated resources in an idle state after the radio connection is released; and responsive to receiving a message from the eNB indicating a release of the allocated resources, releasing the allocated resources.

Abstract: The present invention is to provide a method and device for controlling transmission power by taking comprehensive consideration not only of the effect received onto itself in each device-to-device (D2D) link of a D2D communication network but also of the effect exerted onto the neighboring links.

Abstract: The present disclosure relates to a device-to-device (D2D) communication for direct communication between nodes in a wireless communication system, wherein an operation method of a terminal includes the steps of: generating sequences, which belong to an orthogonal sequence set, according to a sequence pattern corresponding to a priority of a link; and transmitting the sequences, as signals for measurement of a reception electric power of a counterpart terminal, through sub-blocks within a channel, wherein one sequence is transmitted through each of the sub-blocks.

Abstract: Different resources are selected based on QoS, emergency class, location, and SA count. A method for avoiding resource collision by a first User Equipment (UE) in a mobile communication system is provided. The method includes listening to Scheduling Assign (SA) information of a second UE; and selecting different resources between UEs based on the SA information.

Abstract: A method to manage a Radio Resource Control (RRC) connection in an evolved NodeB (eNB) in a wireless communication system supporting a Device to Device (D2D) scheme is provided. The method includes starting an inactivity timer to control a User Equipment (UE) to transition into an RRC idle state after setting up an RRC connection with the UE. The method also includes allocating a D2D resource to the UE when a resource request message to request the D2D resource for a direct communication between UEs is received from the UE. The method further includes transmitting a resource response message including information related to the allocated D2D resource to the UE and stopping the inactivity timer. The method includes releasing the allocated D2D resource and restarting the inactivity timer based on a predetermined option.

Abstract: A method and a device for generating a CID for D2D communication are provided. A transmitting device transmits a request for direct communication between the transmitting device and a receiving device on a resource unit of a first resource index determined based upon at least one of a device ID of the transmitting device or of the receiving device during a first period, receives information about at least one used CID being used by at least one surrounding device from the peripheral device during a second period, transmits information including at least one available CID acquired during the second period on a resource unit of a second resource index being identical to the first resource index during a third period, and determines at least one CID to be used for D2D communication between the transmitting device and the receiving device based on the transmitted information.

Abstract: A method and an apparatus handle an emergency in a wireless communication system. A method of a serving Base Station (BS) for detecting an emergency in a wireless communication system includes receiving an emergency call signal from Mobile Stations (MSs) in a cell; determining whether the number of the received emergency call signals exceeds a threshold number of times; when the number of the received emergency call signals exceeds the threshold number of times, detecting an emergency of a BS; and transmitting a message indicating the emergency to an MS in the cell.

Abstract: A method and an apparatus for broadcasting data using a frame structure having a plurality of sections in a system performing inter-device direct communication are provided. In the method, whether there is data to broadcast is determined. Broadcast indicate information is exchanged with neighbor devices via a retrieve section for retrieving information about neighbor devices, the broadcast indicate information representing an indication of whether data is broadcast. A data transmission section is divided into a broadcast section and a unicast section. A broadcast signal is received during the broadcast section.

Abstract: A method and an apparatus of requiring uplink resources for transmitting a ranging request message in a communication system are provided. The method includes allocating an uplink bandwidth from a base station, and fragmentizing a Ranging Request (RNG-REQ) message into plural fragmented RNG-REQ messages, when the allocated bandwidth does not accommodate an entire RNG-REQ message, requesting an additional uplink bandwidth by transmitting one fragmented RNG-REQ message, and allocating an requested additional uplink bandwidth from the base station and transmitting a next one fragmented RNG-REQ message.

Abstract: Beam selection is provided. A method for handover in a mobile station includes sending a scan request message for scanning a downlink (DL) beam with respect to a serving base station (BS) and a neighboring BS, to the serving BS, and receiving a scan response message; determining the DL beam for the MS by performing scanning with the serving BS and the neighboring BS based on the scan response message; sending a scan report message comprising a result of the scanning to the serving BS; when receiving an air-HO request message from the serving BS, generating an air-HO response message comprising information of a neighboring BS to which the MS hands over based on the air-HO request message; performing beam selection with the neighboring BS of the handover based on the air-HO request message; and performing the handover.

Abstract: A method performed by a device for performing synchronization between devices for a Device-to-Device (D2D) communication is provided. The method includes setting, according to a process of the device, the device to a group of devices for performing a dynamic switching; outputting a synchronization signal corresponding to the set group as a signal for setting synchronization in a physical layer; controlling, upon receiving another synchronization signal from another device, the outputting of the synchronization signal by applying a time offset according to a relation between the set group that includes the device and the group that includes the another device; and setting, if the synchronization signal and the another synchronization signal are converged, synchronization of the device based on a time point where the synchronization signal is output.

Abstract: A method and an apparatus for obtaining synchronization of a terminal for communication between devices when a base station collapses are provided. The method includes, when a preamble signal is not received from the base station, maintaining a first synchronization for a predetermined time using a timer, transmitting a first preamble signal at a first synchronization point, performing a synchronization procedure with at least one neighbor terminal based on the first preamble signal, and, after the synchronization procedure, performing communication with the at least one neighbor terminal. In addition, when a preamble signal is not received from a base station, a first preamble signal from a relevant neighbor terminal is monitored for a predetermined time. When the first preamble signal is not received from the relevant neighbor terminal for the predetermined time, a second preamble signal is transmitted at an arbitrary point.