Abstract: A communication device according to an embodiment comprises: a controller configured to perform radio communication with another communication device in a mobile communication system to which an MDT function is applied. The controller obtains an MDT measurement result obtained by measuring a parameter in the radio communication. The parameter is a parameter affected by a latency reduction function. The controller adds, to the MDT measurement result, identification information on whether or not the latency reduction function is applied, depending on whether or not the latency reduction function is applied to the radio communication.

Abstract: A base station according to a first feature uses a plurality of carriers for radio communications. The base station includes: a receiver that receives neighbor base station information on user terminals connected to a neighbor base station, wherein the neighbor base station information is transmitted from the neighbor base station; and a controller that changes a carrier configuration of at least one carrier among the plurality of carriers based on the neighbor base station information.

Abstract: A user terminal according to a first embodiment is used in a mobile communication system configured to support Device to Device (D2D) communication that is direct device-to-device communication. The user terminal comprises a transmitter configured to transmit, out of a cell coverage, a signal to another user terminal synchronized with the user terminal; a receiver configured to receive a signal from the another user terminal; a storage configured to store a D2D discovery signal resource pool, and a transmission probability parameter indicating a probability of transmission of a D2D discovery signal in the D2D discovery signal resource pool; and a controller configured to execute a process of adjusting the transmission probability parameter in accordance with a resource usage amount in the D2D discovery signal resource pool.

Abstract: In a communication control method according to a present embodiment, at least one radio terminal of a first radio terminal and a second radio terminal discoveries the other radio terminal by executing a discovery for discovering a proximal terminal. The at least one radio terminal reports, to a network apparatus that the other radio terminal is discovered. The network apparatus requests, while the first radio terminal is located within a coverage of a cell, at least one of the first radio terminal and the second radio terminal to make a preparation for executing a relay by the second radio terminal by utilizing a proximal service.

Abstract: A base station according to a present embodiment is a base station configured to manage a cell, and comprises: a controller configured to transmit, if a relay terminal configured to relay data by direct communication between a remote terminal and a network is not present in a vicinity of a radio terminal located within the cell, control information to the radio terminal. The control information is information for starting transmission of a discovery signal for discovering another radio terminal that can be the relay UE.

Abstract: D2D communication is appropriately controlled even in an environment in which a second user terminal inside the coverage and a first user terminal outside the coverage both exist. The first user terminal directly receives from the second user terminal device-to-device (D2D) synchronization information including coverage information that indicates that the second user terminal is in the coverage area, determines, based on the coverage information, whether the second user terminal is in the coverage area, selects the second user terminal as a synchronization reference of the first user terminal in response to determining that the second user terminal is in the coverage area, and receives usable resource information broadcasted from the second user terminal that becomes the synchronization reference, the usable resource information indicating D2D usable resources notified from a base station to the second user terminal by broadcast signaling.

Abstract: A radio terminal according to an embodiment includes a controller configured to control a random access procedure. The random access procedure includes first processing of transmitting a random access preamble to a base station, second processing of receiving a random access response from the base station, and third processing of performing uplink transmission to the base station based on the random access response. The controller is configured to notify, in the first processing or the third processing, the base station of an amount of uplink data in a transmission buffer of the radio terminal.

Abstract: A communication method according to an embodiment, comprising: transmitting, from a base station to a radio terminal, a list indicating association between an identification of a logical channel group and a priority; generating, by the radio terminal, a buffer status report for direct communication; and transmitting, from the radio terminal to the base station, the buffer status report. The buffer status report includes an index of an destination identifier, an identifier of the logical channel group, and a buffer amount associated with the identifier of the logical channel group. In the generating the buffer status report, the radio terminal generates the buffer status report based on the list.

Abstract: User terminal comprises a transmitter configured to transmit, in response to a received power of a signal from another user terminal satisfying a predetermined condition, direct communication in a proximity service without transmitting a synchronization signal in the proximity service, in a case where the user terminal is out of a network coverage.

Abstract: UE 100 receives, when a connection with eNB 200 is established by the UE 100, from the eNB 200, preamble information indicating a random access preamble to be used in a random access procedure when establishing again a connection with the eNB 200. The UE 100 holds, without discarding, the preamble information even when the UE 100 establishes a connection with AP 300 and releases the connection with the eNB 200.

Abstract: A radio terminal according to an embodiment comprises: a controller configured to execute processing of establishing connection with a network for relaying using a Device to Device (D2D) proximity service; a transmitter configured to transmit a discovery message for the relaying, after the connection is established; and a receiver configured to receive a request message from another radio terminal that has received the discovery message, wherein the request message includes an identifier of the another radio terminal. The controller executes control of transmitting the identifier of the another radio terminal, to a network apparatus included in an Evolved Packet Core (EPC), as an identifier of a remote node to which data is relayed by the relaying. The controller executes control of further transmitting the identifier of the another radio terminal to the network apparatus, based on non-reception of a predetermined message from the another radio terminal.

Abstract: A radio terminal according to one embodiment is used in a mobile communication system. The radio terminal comprises a controller configured to perform control related to a DRX operation for intermittently monitoring a downlink control channel based on a comparison result of a value related to a moving speed of the radio terminal and a threshold value when the extended DRX operation is set from a network.

Abstract: A communication method including transmitting, from a radio terminal connected to a cell to a base station managing the cell operated in a first frequency, a first message that a discovery signal is transmitted for public safety in a second frequency; receiving, by the base station, the first message; and transmitting, from the base station to the radio terminal, a second message including information on radio resources to be used in transmission of the discovery signal in the second frequency, based on the first message. The method further includes transmitting, from the base station to the radio terminal, first information and second information. The first information indicates a threshold value for determining whether or not the radio terminal transmits the first message. The radio terminal uses the second information to determine whether or not the radio terminal is allowed to transmit the first message.

Abstract: A radio terminal UE according to one embodiment includes a radio communication unit 210 configured to receive a plurality of parameters including a first parameter for high-speed movement and a second parameter for non-high-speed movement as parameters for processing for switching to a neighboring base station from a base station connected to the radio terminal, and a controller 260 configured to acquire movement speed information indicating a movement speed of the radio terminal and to select a parameter corresponding to the movement speed information. The first parameter is configured to inhibit processing for switching to a Pico base station PeNB which is included in the neighboring base stations.

Abstract: A communication method according to an embodiment comprises: a step of performing, by a user terminal, a reselection of a target cell to be used as a serving cell from among a plurality of cells operated at different frequencies. The step of performing the reselection of the target cell comprises: a first reselection step of performing, by the user terminal, the reselection of the target cell in a response to reception of a paging signal for requesting the reselection of the target cell from a current serving cell; and a second reselection step of performing, by the user terminal, the reselection of the target cell in a response to a trigger without dependence on the paging signal. In the first reselection step, the user terminal starts measurement of a quality of a measurement target frequency included in system information broadcast from the current serving cell, in response to the reception of the paging signal.

Abstract: A user terminal includes: a controller configured to perform, in accordance with one selection rule of a first selection rule and a second selection rule, as a selection rule applied to a cell reselection in an idle mode. The first selection rule is a selection rule for selecting an appropriate cell irrespective of whether the user terminal has an interest in a D2D proximity service. The second selection rule is a selection rule for preferentially selecting, as an appropriate cell, a cell belonging to a frequency available for the D2D proximity service, in case that the user terminal has the interest in the D2D proximity service. The controller applies, in accordance with configuration, the second selection rule instead of the first selection.

Abstract: A base station comprises a transmitter configured to transmit, to a user terminal, information indicating at least any one of a first DRX cycle, a second DRX cycle, and a third DRX cycle. The DRX cycle indicates a cycle during which a user terminal discontinuously monitors a downlink control channel transmitted from a base station. The second DRX cycle has a cycle longer than the first DRX cycle. The third DRX cycle has a cycle longer than the second DRX cycle.

Abstract: A communication method according to an embodiment comprises: notifying, by a base station, a radio terminal of a discontinuous reception (DRX) cycle; notifying, by a Mobility Management Entity (MME), the radio terminal of an extended DRX cycle longer than the DRX cycle; determining, by the radio terminal, whether or not the base station supports an extend DRX; using, by the radio terminal, the extended DRX cycle to execute an extended DRX operation in an idle mode, in response to determining that the base station supports the extend DRX; and using, by the radio terminal, the DRX cycle to execute a DRX operation without using the extended DRX cycle, in response to determining that the base station does not support the extend DRX.

Abstract: A base station according to the present embodiment receives, if the radio terminal is in a connected mode, via a bearer between the base station and a serving gateway, downlink data addressed to the radio terminal, from the serving gateway, and includes a controller configured to transmit the downlink data to the radio terminal. The controller does not release but maintains the bearer, if the extended DRX operation is configured to the radio terminal, when the radio terminal transitions to the idle mode. The controller receives, even if the radio terminal is in the idle mode, from the serving gateway, the downlink data addressed to the radio terminal, via the bearer, and buffers the downlink data until the downlink data is transmitted to the radio terminal.

Abstract: A user terminal includes a transmitter configured to transmit a Device-to-Device (D2D) indication to a serving cell in response to the user terminal being interested in D2D proximity service, while the user terminal is in a Radio Resource Control (RRC) connected mode in the serving cell.