Abstract: The communication system includes: a first base station to which a first communication terminal is connected, the first communication terminal supporting terminal-to-terminal communication in which communication terminals directly communicate with each other; and a second base station to which a second communication terminal is connected, the second communication terminal supporting the terminal-to-terminal communication, and in a case where the second base station receives a handover request for the first communication terminal to connect to the second base station via the second communication terminal, the second base station transmits, to the first communication terminal and the second communication terminal, communication configuration information indicating the content of a configuration for the first communication terminal and the second communication terminal to perform terminal-to-terminal communication therebetween.

Abstract: Provided is a communication system capable of suppressing increase in the power consumption of a communication terminal device, degradation in the communication quality, and reduction in the use efficiency of radio resources. A base station device (gNB) notifies a communication terminal device (UE) of information on the next reception timing. The UE receives, for example, a downlink control signal in a subframe. The UE obtains, from the downlink control signal, information on a piece of user data in the subframe, and the information on the next reception timing. The UE transmits and receives the piece of user data to and from the gNB. The information on the next reception timing indicates a subframe as the next reception timing of the UE. The UE receives a downlink control signal in the subframe.

Abstract: A highly reliable communication system is provided, for example. A communication system includes a communication terminal device, and a plurality of base stations configured to perform radio communication with the communication terminal device. The plurality of base stations include a master base station and a secondary base station configuring dual connectivity with respect to the communication terminal device. When failure occurs in a secondary cell group (SCG) used for communication between the communication terminal device and the secondary base station, the master base station acquires latest SCG configuration.

Abstract: Provided is a high-speed communication system with the high reliability and the low latency under New Radio (NR). A base station device includes a plurality of distributed units (DUs, 802) that transmit and receive radio signals, and a central unit (CU, 801) that controls the plurality of DUs (802). The CU (801) duplicates a downlink packet addressed to a communication terminal device (804), and forwards the duplicated downlink packet to each of at least two DUs (802) among the plurality of DUs (802). Each of the at least two of the DUs (802) transmits, to the communication terminal device (804) by the radio signal, the downlink packet obtained from the CU (801). Upon redundant receipt of the downlink packets, the communication terminal device (804) removes a redundant downlink packet in accordance with a predefined downlink packet removal criterion.

Abstract: Provided is a communication system with low latency and high reliability, etc. Even after transitioning from RRC_CONNECTED to RRC_INACTIVE, a communication terminal device maintains secondary base station configuration information on configuring a secondary base station. Even when at least one of a master base station and a secondary base station is changed during the RRC_INACTIVE, the communication terminal device maintains the secondary base station configuration information. The communication terminal device again transitions to the RRC_CONNECTED using the maintained secondary base station configuration information.

Abstract: Provided is a high-speed communication system with the high reliability and the low latency under New Radio (NR). A base station device includes a plurality of distributed units (DUs, 802) that transmit and receive radio signals, and a central unit (CU, 801) that controls the plurality of DUs (802). The CU (801) duplicates a downlink packet addressed to a communication terminal device (804), and forwards the duplicated downlink packet to each of at least two DUs (802) among the plurality of DUs (802). Each of the at least two of the DUs (802) transmits, to the communication terminal device (804) by the radio signal, the downlink packet obtained from the CU (801). Upon redundant receipt of the downlink packets, the communication terminal device (804) removes a redundant downlink packet in accordance with a predefined downlink packet removal criterion.

Abstract: Provided is a technology that can maintain the reliability and the transmission rate in the communication. A communication system includes a communication terminal, and a first base station and a second base station that are configured to perform radio communication with the communication terminal. The first base station notifies the second base station of information on a numerology to be used for communication between the first base station and the communication terminal when the first base station and the second base station provide the communication terminal with dual connectivity using a same frequency band (Steps ST1501 and ST1502).

Abstract: A communication system includes base stations and a communication terminal. Once the communication terminal connected to a base station enters a state in which communication with another communication terminal is available, the other communication terminal being served by another base station, the communication terminal notifies the base station of connection state information indicating that the communication terminal has entered the state. The base station determines, based on the information, whether to change a connection destination of the communication terminal, to the other base station via the other communication terminal, and requests the communication terminal to release connection with the base station in response to determining to change the connection destination In response to being requested by the base station to release the connection, the communication terminal releases the connection, and connects to the other base station via the other communication terminal.

Abstract: Radio resource management is simplified when a cell is spatially separated by a plurality of radio beams. A cell configured by a base station device is spatially separated by a plurality of radio beams being served by the base station device. The base station device shares, between two or more of the plurality of radio beams, a radio resource control (RRC) parameter to be applied to a communication terminal device.

Abstract: A communication terminal is capable of sidelink communication for directly communicating with another communication terminal. When being in coverage of a base station, the communication terminal is given an allocation for executing, on behalf of a higher-level device in a core network, all or part of a location management function (LMF) including a position derivation function that is a function of deriving a position of a communication terminal. The communication terminal executes, based on a result of the sidelink communication with another communication terminal, a positioning function of deriving a position of the other communication terminal, instead of the higher-level device.

Abstract: A communication system includes: a base station; and a communication terminal connected to the base station, and in a case where the base station causes the communication terminal to transmit a data signal, the base station notifies the communication terminal of information about a demodulation reference signal to be transmitted together with a data signal, and the communication terminal transmits a data signal and a demodulation reference signal in accordance with the information provided from the base station.

Abstract: A communication system includes a base station and a communication terminal connected to the base station. The base station transmits a result of reception of an uplink positioning signal transmitted by the communication terminal and location information of the base station to a positioning device that is a device having a positioning function of deriving a location of the communication terminal, and the communication terminal transmits a result of reception of a downlink positioning signal transmitted by the base station to the positioning device.

Abstract: A communication system includes a user apparatus; and base stations respectively configured to wirelessly communicate with the user apparatus. The base stations include a master base station and a secondary base station that configure dual connectivity for the user apparatus. The secondary base station is configured with a grant configuration related to transmission without grant in uplink to the secondary base station.

Abstract: Radio resource management is simplified when a cell is spatially separated by a plurality of radio beams. A cell configured by a base station device is spatially separated by a plurality of radio beams being served by the base station device. The base station device shares, between two or more of the plurality of radio beams, a radio resource control (RRC) parameter to be applied to a communication terminal device.

Abstract: A communication system that can reduce latency while preventing reduction in a transmission rate. An eNB communicates with a UE #1 using a self-contained subframe including a first downlink signal (DL #1) and a first uplink signal (UL #1), and with a UE #2 using a self-contained subframe including a second downlink signal (DL #2) and a second uplink signal (UL #2). The self-contained subframe for the UE #1 includes a first gap duration (Gap #1) during which neither the DL #1 nor the UL #1 is transmitted, between transmission durations of the DL #1 and the UL #1. The self-contained subframe for the UE #2 includes a second gap duration (Gap #2) during which neither the DL #2 nor the UL #2 is transmitted, between transmission durations of the DL #2 and the UL #2. The Gaps #1 and #2 are set to each UE.

Abstract: The power consumption is reduced in a communication system using Device-to-Device communication. The communication system includes: a base station; a first communication terminal configured to perform radio communication with the base station; and a second communication terminal configured to perform Device-to-Device communication with the first communication terminal. The first communication terminal is configured to relay communication between the second communication terminal and the base station. The first communication terminal releases connection with the base station and transitions to an idle state in the absence of data to be transmitted and received between the second communication terminal and the base station for a predetermined period (Steps ST1411 to ST1415).

Abstract: A communication system including a communication terminal, a base station configured to perform radio communication with the communication terminal, and a management device managing access to the communication terminal through the base station. The communication terminal starts a predefined process for changing Closed Access Group (CAG) information. The management device transmits the CAG information to the communication terminal in response to starting the predefined process by the communication terminal.

Abstract: Provided is a radio communication technology that can achieve low latency, high reliability, and low jitter characteristics. A transmitter is configured to duplicate a packet and transmit the duplicated packets. The receiver is configured to receive the duplicated packets. The receiver is configured to transfer, to an upper layer in the receiver, a first packet (1401, 1403, 1405, 1408) that is a packet received earlier out of the duplicated packets. A transfer timing that is a timing with which the first packet (1401, 1403, 1405, 1408) is transferred to the upper layer includes at least one of: a reception timing of a second packet (1402, 1404, 1406, 1407) that is a packet received later than the first packet out of the duplicated packets; and a cyclical timing (Cycle time) corresponding to a transmission cycle of the duplicated packets.

Abstract: A communication system includes a communication terminal, and a serving base station of the communication terminal. The serving base station notifies the communication terminal of an instruction to configure a measurement gap for the communication terminal to measure a positioning signal transmitted from at least one neighboring base station in order to measure a position of the communication terminal, without a request from the communication terminal (Step ST1417).

Abstract: A user apparatus in a communication system includes: a plurality of user apparatuses each of which is configured to transmit a sounding reference signal (SRS); and a base station configured to wirelessly communicate with the plurality of the user apparatuses. The user apparatus receives, from the base station, configuration information related to a wireless resource of the sounding reference signal allocated to another user apparatus.