Abstract: A radio terminal according to one embodiment comprises a controller configured to transmit a physical uplink shared channel to a base station by an interlace mapping using a plurality of resource blocks distributed on a frequency axis while overlapping on a time axis. The controller receives, from the base station, control channel information on a time-frequency resource used for transmitting the physical uplink control channel. The controller stops transmission in a specific resource block corresponding to the time-frequency resource from among the plurality of resource blocks, based on the control channel information.

Abstract: A radio terminal performs radio communication with a base station in a mobile communication system. The radio terminal includes a controller configured to perform processing of transmitting an aperiodic CSI feedback related to a downlink channel state to the base station. In response to a predetermined condition being satisfied, the controller performs multiplex transmission in which uplink data in which the aperiodic CSI feedback is multiplexed is transmitted to the base station, by using a PUSCH resource.

Abstract: A radio terminal according to one embodiment comprises: a controller configured to detect a radio problem in communication with a base station in an RRC connected state and attempt a recovery from the radio problem; and a transmitter configured to transmit, to the base station, a polling signal for confirming whether or not the base station considers an RRC state of the radio terminal as the RRC connected state in response to the successful recovery. The controller maintains the RRC connected state in response to reception, from the base station, of a response signal to the polling signal.

Abstract: A base station causes a radio terminal to transition to a specific state. The specific state is a state in which signaling for the radio terminal is suppressed compare to an RRC connected state while a connection for the radio terminal is maintained between the base station and a core network. The base station transmits to an entity of the core network, an identifier identifying the radio terminal and a first RRC transition notification indicting that the radio terminal transitions from the RRC connected state to the specific state. The base station causes the radio terminal to transition from the specific state to the RRC connected state. The base station transmits to the entity, a second RRC transition notification indicting that the radio terminal transitions from the specific state to the RRC connected state.

Abstract: A user equipment for a mobile communication system, includes: a receiver configured to receive, from a base station, an RRC (Radio Resource Control) connection release message including information instructing a transition to a specific state; and a controller configured to cause the user equipment to transit to the specific state in response to receiving the RRC connection release message including the information. The specific state is a different RRC state from an RRC connected and an RRC idle, and a connection for the user equipment is maintained between the base station and a core network.

Abstract: A radio terminal according to one embodiment is configured to perform a relay between another radio terminal and a network. The radio terminal comprises: a transmitter configured to notify the network of first information indicating that the radio terminal is a relay terminal of the another radio terminal; a controller configured to forward data addressed to the another radio terminal to the another radio terminal via a connection between the another radio terminal through the radio terminal and the network; and a receiver configured to receive from the network a message indicating that the data addressed to the another radio terminal exists when at least part of the connection is released. The controller is configured to start control for establishing the connection in order to forward the data addressed to the another radio terminal in response to receiving the message.

Abstract: A communication device according to one embodiment includes a controller and a transmitter. The controller is configured to identify a zone that is a geographical section where the communication device is located, and select a predetermined transmission resource region from a plurality of transmission resource regions included in one transmission resource pool associated with the identified zone. The transmitter is configured to transmit a direct radio signal to another communication device by using a resource in the predetermined transmission resource region.

Abstract: A radio terminal according to one embodiment comprises a controller configured to perform radio communication in a time division duplex system, with a base station. The controller is configured to receive a downlink radio signal from the base station; and transmit to the base station, response information indicating whether reception of the downlink radio signal is successful, wherein the response information is transmitted by using an uplink radio resource different from an uplink control channel resource even if the uplink radio resource is not allocated for data transmission from the base station.

Abstract: A communication apparatus according to one embodiment includes a receiver configured to receive predetermined information from a base station. The predetermined information indicates a corresponding relationship between identification information for identifying multicast data and area identification information for identifying a geographical area. The receiver is configured to receive predetermined multicast data from the base station based on the predetermined information. The predetermined multicast data includes data from another communication apparatus in a first area in which the communication apparatus is located.

Abstract: A radio terminal according to one embodiment comprises a controller configured to transmit a physical uplink shared channel to a base station by an interlace mapping using a plurality of resource blocks distributed on a frequency axis while overlapping on a time axis. The controller receives, from the base station, control channel information on a time-frequency resource used for transmitting the physical uplink control channel. The controller stops transmission in a specific resource block corresponding to the time-frequency resource from among the plurality of resource blocks, based on the control channel information.

Abstract: A radio terminal according to one embodiment comprises: a controller configured to detect a radio problem in communication with a base station in an RRC connected state and attempt a recovery from the radio problem; and a transmitter configured to transmit, to the base station, a polling signal for confirming whether or not the base station considers an RRC state of the radio terminal as the RRC connected state in response to the successful recovery. The controller maintains the RRC connected state in response to reception, from the base station, of a response signal to the polling signal.

Abstract: A radio terminal according to one embodiment is configured to perform a relay between another radio terminal and a network. The radio terminal comprises: a transmitter configured to notify the network of first information indicating that the radio terminal is a relay terminal of the another radio terminal; a controller configured to forward data addressed to the another radio terminal to the another radio terminal via a connection between the another radio terminal through the radio terminal and the network; and a receiver configured to receive from the network a message indicating that the data addressed to the another radio terminal exists when at least part of the connection is released. The controller is configured to start control for establishing the connection in order to forward the data addressed to the another radio terminal in response to receiving the message.

Abstract: A user equipment for a mobile communication system, includes: a receiver configured to receive, from a base station, an RRC (Radio Resource Control) connection release message including information instructing a transition to a specific state; and a controller configured to cause the user equipment to transit to the specific state in response to receiving the RRC connection release message including the information. The specific state is a different RRC state from an RRC connected and an RRC idle, and a connection for the user equipment is maintained between the base station and a core network.

Abstract: A user equipment comprises a receiver configured to receive a first message from a first cell and a controller configured to apply, based on the first message, one of first configuration information and second configuration information to determine a zone that is a geographical section. The first configuration information is information pre-configured in the user equipment. The second configuration information is information provided from the first cell. The controller determines a zone in which the user equipment is located based on the applied one of the first configuration information and the second configuration information and performs Vehicle-to-Everything (V2X) communication based on a resource pool associated with the determined zone.

Abstract: A communication device according to one embodiment includes a controller and a transmitter. The controller is configured to identify a zone that is a geographical section where the communication device is located, and select a predetermined transmission resource region from a plurality of transmission resource regions included in one transmission resource pool associated with the identified zone. The transmitter is configured to transmit a direct radio signal to another communication device by using a resource in the predetermined transmission resource region.

Abstract: A radio terminal performs radio communication with a base station in a mobile communication system. The radio terminal includes a controller configured to perform processing of transmitting an aperiodic CSI feedback related to a downlink channel state to the base station. In response to a predetermined condition being satisfied, the controller performs multiplex transmission in which uplink data in which the aperiodic CSI feedback is multiplexed is transmitted to the base station, by using a PUSCH resource.

Abstract: A communication apparatus according to one embodiment includes a receiver configured to receive predetermined information from a base station. The predetermined information indicates a corresponding relationship between identification information for identifying multicast data and area identification information for identifying a geographical area. The receiver is configured to receive predetermined multicast data from the base station based on the predetermined information. The predetermined multicast data includes data from another communication apparatus in a first area in which the communication apparatus is located.

Abstract: A base station causes a radio terminal to transition to a specific state. The specific state is a state in which signaling for the radio terminal is suppressed compare to an RRC connected state while a connection for the radio terminal is maintained between the base station and a core network. The base station transmits to an entity of the core network, an identifier identifying the radio terminal and a first RRC transition notification indicting that the radio terminal transitions from the RRC connected state to the specific state. The base station causes the radio terminal to transition from the specific state to the RRC connected state. The base station transmits to the entity, a second RRC transition notification indicting that the radio terminal transitions from the specific state to the RRC connected state.

Abstract: A radio terminal according to one embodiment comprises a controller configured to perform radio communication in a time division duplex system, with a base station. The controller is configured to receive a downlink radio signal from the base station; and transmit to the base station, response information indicating whether reception of the downlink radio signal is successful, wherein the response information is transmitted by using an uplink radio resource different from an uplink control channel resource even if the uplink radio resource is not allocated for data transmission from the base station.

Abstract: Provided are a radio communication system, a radio communication apparatus, a radio communication terminal, and a communication method those being capable of facilitating handover of a dual terminal to a base station corresponding to the other communication scheme, thereby improving frequency utilization efficiency of the entire radio communication system that employs a plurality of communication schemes. Specifically, a first radio communication apparatus (1) is provided with a transmission unit (100) for transmitting information (106) about a backbone line shared with a second radio communication apparatus (2). A first radio communication terminal (3) and a second radio communication terminal (4) are provided with a selection unit (32) and a selection unit (41), respectively, for selecting a radio communication apparatus to connect based on the information (106) received.