Abstract: There are provided a method for processing an exceptional case of establishing a default bearer and a device therefor in order to solve a problem in that a user equipment cannot actually receive an IP service by accessing a packet network while failing in establishing the default bearer in a mobile communication system. A method for processing an exceptional ease of establishing a default hearer in a mobility management entity includes: receiving a network attachment request from a user equipment; transmitting a network attachment acceptance including an activation request of the default bearer to the user equipment in response to the network attachment request; and cancelling a network attachment procedure when a completion response to the activation request of the default bearer is not received from the user equipment within a predetermined time.

Abstract: There are provided a method for processing an exceptional case of establishing a default bearer and a device therefor in order to solve a problem in that a user equipment cannot actually receive an IP service by accessing a packet network while failing in establishing the default bearer in a mobile communication system. A method for processing an exceptional ease of establishing a default hearer in a mobility management entity includes: receiving a network attachment request from a user equipment; transmitting a network attachment acceptance including an activation request of the default bearer to the user equipment in response to the network attachment request; and cancelling a network attachment procedure when a completion response to the activation request of the default bearer is not received from the user equipment within a predetermined time.

Abstract: There are provided a method for processing an exceptional case of establishing a default bearer and a device therefor in order to solve a problem in that a user equipment cannot actually receive an IP service by accessing a packet network while failing in establishing the default bearer in a mobile communication system. A method for processing an exceptional case of establishing a default bearer in a mobility management entity includes: receiving a network attachment request from a user equipment; transmitting a network attachment acceptance including an activation request of the default bearer to the user equipment in response to the network attachment request; and cancelling a network attachment procedure when a completion response to the activation request of the default bearer is not received from the user equipment within a predetermined time.

Abstract: Disclosed are user equipment and a base station in a carrier aggregation system, and a call admission method thereof. The user equipment includes a plurality of physical layers, and the base station provides multiple component carriers. When messages for connection setup are transmitted and received between the user equipment and base station, the messages include information about what component carriers are selected by the physical layers, information about what component carriers are selectable by the physical layers, and information about calculations for uplink timing alignment, and call admission control and load balancing is performed based on the information included in the messages. Accordingly, in the carrier aggregation system, quicker call admission and load balancing are achieved.

Abstract: There are provided a method for processing an exceptional case of establishing a default bearer and a device therefor in order to solve a problem in that a user equipment cannot actually receive an IP service by accessing a packet network while failing in establishing the default bearer in a mobile communication system. A method for processing an exceptional case of establishing a default bearer in a mobility management entity includes: receiving a network attachment request from a user equipment; transmitting a network attachment acceptance including an activation request of the default bearer to the user equipment in response to the network attachment request; and cancelling a network attachment procedure when a completion response to the activation request of the default bearer is not received from the user equipment within a predetermined time.

Abstract: A method for synchronization by a D2D terminal in a D2D communication network through receiving a first D2D synchronization signal from at least one D2D synchronization source and performing synchronization according to a synchronization timing reference provided through the first D2D synchronization signal, and a method for negotiating whether to perform a role as a synchronization source with another D2D synchronization source through determining, when a D2D synchronization signal and a D2D synchronization channel are received from at least one D2D synchronization source, whether to maintain a role as the independent synchronization source based on negotiation information for negotiation between synchronization sources included in the D2D synchronization channel, and operating as a relaying synchronization source when the role as the independent synchronization source is not maintained, are provided.

Abstract: There are provided a method for processing an exceptional case of establishing a default bearer and a device therefor in order to solve a problem in that a user equipment cannot actually receive an IP service by accessing a packet network while failing in establishing the default bearer in a mobile communication system. A method for processing an exceptional ease of establishing a default hearer in a mobility management entity includes: receiving a network attachment request from a user equipment; transmitting a network attachment acceptance including an activation request of the default bearer to the user equipment in response to the network attachment request; and cancelling a network attachment procedure when a completion response to the activation request of the default bearer is not received from the user equipment within a predetermined time.

Abstract: There are provided a method for processing an exceptional case of establishing a default bearer and a device therefor in order to solve a problem in that a user equipment cannot actually receive an IP service by accessing a packet network while failing in establishing the default bearer in a mobile communication system. A method for processing an exceptional case of establishing a default bearer in a mobility management entity includes: receiving a network attachment request from a user equipment; transmitting a network attachment acceptance including an activation request of the default bearer to the user equipment in response to the network attachment request; and cancelling a network attachment procedure when a completion response to the activation request of the default bearer is not received from the user equipment within a predetermined time.

Abstract: A method and apparatus for handover is provided. In a network environment in which a plurality of beams are provided within a base station, a terminal measures signal strength of a serving beam and signal strength of a target beam and transmits a measurement report message when a first condition or a second condition is satisfied. The base station determines inter-beam coordinated scheduling when the signal strength of the serving beam and target beam satisfy the first condition, and determines handover between beams when the signal strength of the serving beam and target beam satisfy the second condition. The base station transmits a message for commanding handover to the terminal when the handover between beams is determined. The terminal then stops communicating with the serving beam and performs handover to the target beam.

Abstract: A UE does not immediately perform handover after receiving a handover command from a serving base station, but instead backups that message and continuously compares the signal strength of a serving base station and the signal strength of a target base station and performs a handover to the target base station at the best timing when handover is required. Once the timing of handover is determined, the UE transmits a handover indication message to the serving base station, and thereafter the UE performs a handover to the target base station.

Abstract: Disclosed are a method and an apparatus for controlling distributed transmission power in device-to-device (D2D) communication. The D2D devices individually control their transmission power for the D2D communication link. In addition, a first terminal calculates the transmission power based on the measured channel gain and interference-plus-noise level. The first terminal determines optimal transmission power based on the calculated transmission power by the first terminal, and transmits a transmission power change message including the optimal transmission power to a second terminal. Next, the second terminal transmits a D2D signal based on the optimal transmission power.

Abstract: There are provided a method for processing an exceptional case of establishing a default bearer and a device therefor in order to solve a problem in that a user equipment cannot actually receive an IP service by accessing a packet network while failing in establishing the default bearer in a mobile communication system. A method for processing an exceptional case of establishing a default bearer in a mobility management entity includes: receiving a network attachment request from a user equipment; transmitting a network attachment acceptance including an activation request of the default bearer to the user equipment in response to the network attachment request; and cancelling a network attachment procedure when a completion response to the activation request of the default bearer is not received from the user equipment within a predetermined time.

Abstract: A method for synchronization by a D2D terminal in a D2D communication network through receiving a first D2D synchronization signal from at least one D2D synchronization source and performing synchronization according to a synchronization timing reference provided through the first D2D synchronization signal, and a method for negotiating whether to perform a role as a synchronization source with another D2D synchronization source through determining, when a D2D synchronization signal and a D2D synchronization channel are received from at least one D2D synchronization source, whether to maintain a role as the independent synchronization source based on negotiation information for negotiation between synchronization sources included in the D2D synchronization channel, and operating as a relaying synchronization source when the role as the independent synchronization source is not maintained, are provided.

Abstract: There is provided a transmission/reception method of a base station in a device to device (D2D) communication environment in which terminals directly communicate with each other. The base station variably sets the transmission power intensity of a downlink signal over time. Furthermore, the base station broadcasts the downlink signal with set transmission power intensity.

Abstract: There are provided a method for processing an exceptional case of establishing a default bearer and a device therefor in order to solve a problem in that a user equipment cannot actually receive an IP service by accessing a packet network while failing in establishing the default bearer in a mobile communication system. A method for processing an exceptional case of establishing a default bearer in a mobility management entity includes: receiving a network attachment request from a user equipment; transmitting a network attachment acceptance including an activation request of the default bearer to the user equipment in response to the network attachment request; and cancelling a network attachment procedure when a completion response to the activation request of the default bearer is not received from the user equipment within a predetermined time.

Abstract: A method and apparatus for handover is provided. In a network environment in which a plurality of beams are provided within a base station, a terminal measures signal strength of a serving beam and signal strength of a target beam and transmits a measurement report message when a first condition or a second condition is satisfied. The base station determines inter-beam coordinated scheduling when the signal strength of the serving beam and target beam satisfy the first condition, and determines handover between beams when the signal strength of the serving beam and target beam satisfy the second condition. The base station transmits a message for commanding handover to the terminal when the handover between beams is determined. The terminal then stops communicating with the serving beam and performs handover to the target beam.

Abstract: A UE does not immediately perform handover after receiving a handover command from a serving base station, but instead backups that message and continuously compares the signal strength of a serving base station and the signal strength of a target base station and performs a handover to the target base station at the best timing when handover is required. Once the timing of handover is determined, the UE transmits a handover indication message to the serving base station, and thereafter the UE performs a handover to the target base station.

Abstract: A D2D (Device-to-Device) communication method is provided which enables a first terminal of a first group to directly communicate with other terminals of the first group without relay of a base station. The first terminal receives first data from a second terminal. The first terminal determines whether the first data is destined for the first group by using a group identifier of the first data. When the first data is destined for the first group, the first terminal identifies at least one first RLC entity, among multiple RLC (Radio Link Control) entities, that corresponds to the second terminal by using the source terminal identifier of the first data.

Abstract: A D2D (Device-to-Device) discovery method is provided which enables a first terminal within a first cell to discover a second terminal within a second cell without relay of a base station. The first terminal receives, from a first base station of the first cell, information about a first resource for D2D discovery through a SIB (System Information Block) or RRC (Radio Resource Control) message. The first terminal transmits a D2D discovery signal using the first resource.

Abstract: A method and apparatus for handover based on cooperation between base stations are provided. When a message indicating handover completion is received from a terminal that has determined whether to perform handover and that has performed handover to a target base station, the target base station transmits a message requesting information on the terminal to a serving base station of the terminal. Then, the target base station receives information on the terminal from the serving base station and transmits data to the terminal.