Abstract: Provided is a technology that can increase the robustness of a communication system. A communication system includes: a communication terminal; a first network configured to perform radio communication with the communication terminal; and at least one second network configured to perform communication with the first network. When the first network determines to release connection between the first network and the communication terminal with the communication terminal being connected to the first network and to the at least one second network through the first network, the communication terminal or the first network instructs the at least one second network to release the connection with the communication terminal.

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: Provided is a radio communication technology with high reliability. A communication system includes a communication terminal, base stations, and a host device of the base stations. A serving base station of the communication terminal or the host device selects, from among the base stations, a positioning base station transmitting a positioning signal for measuring a position of the communication terminal. The positioning base station transmits the positioning signal, and the communication terminal receives the positioning signal.

Abstract: The present invention has an object to prevent failure of communication due to leaving of a communication terminal from a radiation range of a beam selected by the communication terminal. A communication system according to the present invention includes: a base station configured to transmit a plurality of directional beams being different from each other; and a communication terminal configured to perform radio communication with the base station by using a beam for communication selected from the plurality of directional beams. A system information block transmitted by the base station includes, regarding each of the plurality of directional beams, neighboring beam information indicating neighboring beams being adjacent to each of the plurality of directional beams. The communication terminal selects the beam for communication, based on the neighboring beam information.

Abstract: The base station allocates, to one terminal, at least one transmission layer and allocates at least one resource block that is a minimum allocation unit of a communication resource in each transmission layer, to transmit a signal to the terminal, and includes processing units each associated with one of the transmission layers, the processing units being equal in number to the transmission layers. Each processing unit includes a reference signal generation unit to generate a reference signal to be used by the terminal in demodulation processing on a received signal, and an information processing unit to determine an arrangement of the resource block in which to transmit the reference signal to the terminal, based on at least one of a state of a channel between the base station and the terminal or information on the resource block to be used in transmission of the reference signal in an adjacent cell.

Abstract: Provided is a radio communication technology with low latency and high reliability. A communication system includes a communication terminal, and a plurality of communication apparatuses configured to perform radio communication with the communication terminal. When the communication terminal switches a communication apparatus to which the communication terminal is connected from a first communication apparatus to a second communication apparatus, the communication terminal corrects a time of the communication terminal, based on a timing reference to be transmitted from the second communication apparatus and timing advance of the second communication apparatus.

Abstract: A high-speed communication system etc. are provided in New Radio (NR) and LTE. When a secondary base station device detects a data inactive state for all bearers, the secondary base station device notifies a master base station device of occurrence of the data inactive state regardless of absence of an inquiry from the master base station device. The data inactive state is a state in which downlink data for a communication terminal device is inactive. When the master base station device receives the notification about the occurrence of the data inactive state, the master base station device transmits a command to the communication terminal device to transition from an RRC_CONNECTED state to an RRC_INACTIVE state. Based on the command from the master base station device, the communication terminal device transitions to the RRC_INACTIVE state.

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: 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 that is a packet received earlier out of the duplicated packets. A transfer timing that is a timing with which the first packet is transferred to the upper layer includes at least one of: a reception timing of a second packet 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 base station includes a reception processing unit that receives a signal for use in positioning transmitted from a terminal device, and a positioning processing unit that computes the location of the terminal device using the signal for use in positioning.

Abstract: A high-speed communication system etc. are provided in New Radio (NR) and LTE. When a secondary base station device detects a data inactive state for all bearers, the secondary base station device notifies a master base station device of occurrence of the data inactive state regardless of absence of an inquiry from the master base station device. The data inactive state is a state in which downlink data for a communication terminal device is inactive. When the master base station device receives the notification about the occurrence of the data inactive state, the master base station device transmits a command to the communication terminal device to transition from an RRC_CONNECTED state to an RRC_INACTIVE state. Based on the command from the master base station device, the communication terminal device transitions to the RRC_INACTIVE state.

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 (DU) that transmit and receive radio signals, and a central unit (CU) that controls the plurality of DUs. The CU duplicates a downlink packet addressed to a communication terminal device, and forwards the duplicated downlink packet to each of at least two DUs among the plurality of DUs. Each of the at least two of the DUs transmits, to the communication terminal device by the radio signal, the downlink packet obtained from the CU. Upon redundant receipt of the downlink packets, the communication terminal device removes a redundant downlink packet in accordance with a predefined downlink packet removal criterion.

Abstract: A communication system includes a plurality of base stations, and a communication terminal device configured to perform radio communication with the plurality of base stations. Each of the plurality of base stations includes a plurality of distributed units (DUs) configured to perform radio communication with the communication terminal device, and a central unit (CU) configured to control the plurality of DUs. When the communication terminal device selects a connection target DU, the communication terminal device preferentially selects the DU belonging to an immediately preceding CU being the CU to which the DU having been connected in an immediately preceding case belongs over the DU belonging to another CU.

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 high reliability and low latency, etc., under New Radio (NR). A communication system includes a communication terminal device, and a base station device configured to perform radio communication with the communication terminal device. The communication terminal device is configured to duplicate a packet and transmit the duplicated packets with carrier aggregation. The base station device is configured to transmit, to the communication terminal device, packet duplication control on packet duplication and secondary cell control on a secondary cell to be used for the carrier aggregation. The communication terminal device is configured to perform the packet duplication control and the secondary cell control based on priorities defined between the packet duplication control and the secondary cell control.

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: A radio communication technology with small delay is provided. A communication system includes a communication terminal and a base station. The base station includes a plurality of transmitter-receivers configured to perform radio communication with the communication terminal. The base station is configured to perform radio communication with the communication terminal by using a part or all of the plurality of transmitter-receivers. The communication terminal receives a downlink synchronization signal from at least one transmitter-receiver to be newly connected, and establishes downlink synchronization with the at least one transmitter-receiver by using the downlink synchronization signal. The communication terminal receives a random access start order from the base station, performs random access processing by using the random access start order, and establishes uplink synchronization with the at least one transmitter-receiver.

Abstract: A wireless communication system includes a mobile terminal, multiple lower-layer base stations communicating with the mobile terminal, and an upper-layer base station controlling the lower-layer base stations. The upper-layer base station transmits, to the lower-layer base stations, multiple pieces of first data generated by duplication by the upper-layer base station, and the lower-layer base stations transmit the first data to the mobile terminal. The mobile terminal includes link control units receiving the respective first data correspondingly to the respective lower-layer base stations; and a data control unit that, when a first link control unit of the link control units receives the first data from a first lower-layer base station of the lower-layer base stations, transmits a retransmission request stop message to a second link control unit that hasn't received the first data from a second lower-layer base station being a lower-layer base station other than the first lower-layer base station.

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: Provided is a high-speed communication system with high reliability and low latency, etc., under New Radio (NR). A communication system includes a communication terminal device, and a base station device configured to perform radio communication with the communication terminal device. The communication terminal device is configured to duplicate a packet and transmit the duplicated packets with carrier aggregation. The base station device is configured to transmit, to the communication terminal device, packet duplication control on packet duplication and secondary cell control on a secondary cell to be used for the carrier aggregation. The communication terminal device is configured to perform the packet duplication control and the secondary cell control based on priorities defined between the packet duplication control and the secondary cell control.