Abstract: A base station (1) controls state transitions of a radio terminal (2) among first to third RRC states. In addition, the base station (1) explicitly or implicitly informs the radio terminal (2) about whether a network slice configured in the radio terminal (2) for data communication at least in the first RRC state is available in each cell included in a RAN notification area configured by a RAN (3). It is thus, for example, possible to allow a radio terminal in a first state (e.g., RRC_INACTIVE state) to be easily aware of the availability of network slices in a cell to be reselected or a reselected cell.

Abstract: A communication system is disclosed in which a base station performs Listen-Before-Talk (LBT) communication with an item of user equipment (UE) via at least one cell. When the base station of the UE detects a failure associated with the LBT communication in at least one cell, the base station transmits a signalling message to another node (e.g., a central unit, a master node, a secondary node, or a core network node), the signalling message comprising information indicating that LBT failure has been detected. The information is used by the other node in managing the LBT communication with the UE (e.g., releasing resources, deactivating cells, etc.).

Abstract: A target RAN node (3) receives, from a core network (5), a message requesting a handover of a radio terminal (1) from a bearer-based network to a bearer-less network. This handover request message includes flow information related to at least one session to be established in the bearer-less network in order to transfer at least one packet flow of the radio terminal (1). The target RAN node (3) transmits, to the core network (5), a handover acknowledge response message containing a transparent container that includes a radio resource configuration information derived from the flow information and is to be forwarded to a source RAN node associated (2) through the core network (5). It is thus, for example, possible to appropriately configuring an AS layer of a target RAT in an inter-RAT handover.

Abstract: A target RAN node (3) receives, from a core network (5), a message requesting a handover of a radio terminal (1) from a bearer-based network to a bearer-less network. This handover request message includes flow information related to at least one session to be established in the bearer-less network in order to transfer at least one packet flow of the radio terminal (1). The target RAN node (3) transmits, to the core network (5), a handover acknowledge response message containing a transparent container that includes a radio resource configuration information derived from the flow information and is to be forwarded to a source RAN node associated (2) through the core network (5). It is thus, for example, possible to appropriately configuring an AS layer of a target RAT in an inter-RAT handover.

Abstract: A secondary node (2) transmits to a radio terminal (3), via a master node (1), a first RRC message indicating an execution condition of a conditional primary cell change of a primary cell of a secondary cell group from a first cell to a second cell. In addition, the secondary node (2) receives, via the master node (1), a second RRC message that is transmitted from the radio terminal (3) in response to a satisfaction of the execution condition. This contributes to, for example, allowing the secondary node to be aware of a satisfaction of an execution condition of a conditional PSCell change where RRC signaling between the secondary node and the radio terminal is performed via the master node.

Abstract: A radio station (2) transmits or receives, to or from a radio terminal (1) in a second cell (23, 24), a CP message containing a NAS message or an RRC message or both, when a predetermined condition is satisfied. The second cell (23, 24) uses a RAT different from that of the first cell, and is used in addition and subordinate to the first cell. The predetermined condition relates to at least one of: (a) a content or type of the CP message; (b) a type of a signalling radio bearer used to transmit the CP message; (c) a transmission cause of the CP message; and (d) a type of a core network associated with the NAS message. It is thus, for example, possible to contributing to efficient transmission of control plane (CP) messages in a radio architecture that provides interworking of two different Radio Access Technologies (RATs).

Abstract: A secondary base station (2) receives a request message from a master base station (1) of Dual Connectivity. If the secondary base station (2) uses an SN terminated bearer that uses both Master Cell Group (MCG) resources and Secondary Cell Group (SCG) resources, the secondary base station (2) transmits a request acknowledge message containing a UL Configuration information element to the master base station (1) as a response to the request message. This, for example, allows the master base station and the secondary base station to deal with a situation where multiple information elements contained in a control message for the setup of an SN terminated bearer using MCG resources are inconsistent.

Abstract: A radio station (2) transmits configuration information (501) to a radio terminal (1). The configuration information (501) indicates, on a cell-by-cell basis, at least one specific cell on which the radio terminal (1) is allowed to perform at least one of data transmission and data reception on a radio bearer used for uplink transmission or downlink transmission or both via a common Packet Data Convergence Protocol (PDCP) layer (402). As a result, in a radio architecture that provides tight interworking of two different Radio Access Technologies (RATs), it is for example possible to allow an eNB to indicate, to a radio terminal (UE), a specific cell on which the UE should perform uplink transmission.

Abstract: In response to receiving from a source RAN node (2), on a direct interface (101), a message requesting a handover of a radio terminal (1) from a first network to a second network, a target RAN node (3) receives at least one of slice information and flow information from a core network (5), and controls communication of the radio terminal (1) based on at least one of the slice information and the flow information. The slice information relates to a network slice in the second network. The flow information relates to at least one session to be established in the second network, serving as a bearer-less network, in order to transfer at least one packet flow of the radio terminal (1). It is thus possible, for example, to provide an Inter-RAT handover procedure involving transfer of handover signaling messages on a direct inter-base-station interface.

Abstract: A target RAN node (3) is configured to: receive, directly from a core network (5), core network context information about a handover of a radio terminal (1) from a first network to the second network; and control communication of the radio terminal (1) based on the core network context information. The target RAN node (3) is further configured to transfer a handover signaling message to a source RAN node on a direct interface (101) in response to receiving the core network context information. The core network context information includes at least one of flow information, slice information, and security-related information. It is thus possible, for example, to provide an inter-RAT handover procedure involving transfer of handover signaling messages on a direct inter-base-station interface.

Abstract: In order to make it possible to report an amount of data from a secondary node (SN) to a master node (MN) in dual connectivity, there is provided a first unit according to the present disclosure which is a first unit of a central unit of a first base station. The first unit includes a controller and a transceiver. The central unit is configured to host at least PDCP layer in the first base station; and is connected to a distributed unit via a first interface, the distributed unit hosting RLC, MAC and PHY layers in the first base station. The controller is configured to host at least a user plane of the PDCP layer hosted by the central unit; and the transceiver is configured to transmit, to a second unit via a second interface, first information indicative of a volume of data processed by the first unit. The second unit is configured to host at least a control plane of the PDCP layer hosted by the central unit.

Abstract: When a radio terminal (2) in a first RAT RRC_INACTIVE state in the first radio access network (RAN) (3) and having a Non-Access Stratum (NAS) connection with a first core network (CN) (4) associated with the first RAT moves to a cell (51) of a second RAN (6), the radio terminal (2) alters an RRC state transition operation of the radio terminal (2) depending on whether the second RAN (6) supports interworking with at least one of the first CN (4) and the first RAN (3).

Abstract: A base station (1) controls state transitions of a radio terminal (2) among first to third RRC states. In addition, the base station (1) explicitly or implicitly informs the radio terminal (2) about whether a network slice configured in the radio terminal (2) for data communication at least in the first RRC state is available in each cell included in a RAN notification area configured by a RAN (3). It is thus, for example, possible to allow a radio terminal in a first state (e.g., RRC_INACTIVE state) to be easily aware of the availability of network slices in a cell to be reselected or a reselected cell.

Abstract: When a Secondary Cell Group (SCG) containing a Primary SCG Cell (PSCell) is deactivated upon a PSCell addition or a PSCell mobility, a User Equipment (3) performs random access to the PSCell in response to the PSCell addition or the PSCell mobility without waiting until a future SCG activation. This can contribute, for example, to proper random access when the SCG is deactivated.

Abstract: A communication system is disclosed in which am anchor base station receives, from a core network node, downlink data for a communication device. The base station attempts (e.g. by RAN-based paging) to initiate communication with the communication device, and when the communication device does not respond to the attempt to initiate communication, the base station sends a message to the core network node, the message requesting initiation of a paging procedure for the communication device (e.g. S1-based paging).

Abstract: A radio station (2) transmits configuration information (501) to a radio terminal (1). The configuration information (501) indicates, on a cell-by-cell basis, at least one specific cell on which the radio terminal (1) is allowed to perform at least one of data transmission and data reception on a radio bearer used for uplink transmission or downlink transmission or both via a common Packet Data Convergence Protocol (PDCP) layer (402). As a result, in a radio architecture that provides tight interworking of two different Radio Access Technologies (RATs), it is for example possible to allow an eNB to indicate, to a radio terminal (UE), a specific cell on which the UE should perform uplink transmission.

Abstract: A radio station (2) transmits or receives, to or from a radio terminal (1) in a second cell (23, 24), a CP message containing a NAS message or an RRC message or both, when a predetermined condition is satisfied. The second cell (23, 24) uses a RAT different from that of the first cell, and is used in addition and subordinate to the first cell. The predetermined condition relates to at least one of: (a) a content or type of the CP message; (b) a type of a signalling radio bearer used to transmit the CP message; (c) a transmission cause of the CP message; and (d) a type of a core network associated with the NAS message. It is thus, for example, possible to contributing to efficient transmission of control plane (CP) messages in a radio architecture that provides interworking of two different Radio Access Technologies (RATs).

Abstract: This wireless communication system has a first base station, and a second base station whereby downlink data received from a core network can be transmitted to a terminal via the second base station and the first base station. The second base station transmits, to the first base station, information that makes it possible to identify whether or not flow control can be carried out.

Abstract: In order to make it possible to report an amount of data from a secondary node (SN) to a master node (MN) in dual connectivity, there is provided a first unit according to the present disclosure which is a first unit of a central unit of a first base station. The first unit includes a controller and a transceiver. The central unit is configured to host at least PDCP layer in the first base station; and is connected to a distributed unit via a first interface, the distributed unit hosting RLC, MAC and PHY layers in the first base station. The controller is configured to host at least a user plane of the PDCP layer hosted by the central unit; and the transceiver is configured to transmit, to a second unit via a second interface, first information indicative of a volume of data processed by the first unit. The second unit is configured to host at least a control plane of the PDCP layer hosted by the central unit.

Abstract: A communication system is disclosed in which am anchor base station receives, from a core network node, downlink data for a communication device. The base station attempts (e.g. by RAN-based paging) to initiate communication with the communication device, and when the communication device does not respond to the attempt to initiate communication, the base station sends a message to the core network node, the message requesting initiation of a paging procedure for the communication device (e.g. S1-based paging).