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: Provided is a communication system with high reliability, etc. A communication system includes a base station, and a plurality of terminal devices configured to perform radio communication with the base station. When one slot includes a sounding reference signal (SRS) symbol range consisting of one or more symbols allocated to an SRS of a first terminal device, a first symbol range consisting of one or more symbols before the SRS symbol range, and a second symbol range consisting of one or more symbols after the SRS symbol range, a second terminal device different from the first terminal device performs uplink communication to the base station using at least one of the first symbol range and the second symbol range.

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: A radio communication technology for enabling high reliability, a high transmission rate, and low power consumption 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 first transmitter-receiver to be newly connected, and establishes downlink synchronization with the at least one first transmitter-receiver by using the downlink synchronization signal. The communication terminal establishes uplink synchronization with the at least one first transmitter-receiver through random access processing.

Abstract: Provided is a communication system, etc. with low latency and high reliability, under New Radio (NR). A communication system includes a communication terminal device, and a plurality of nodes configured to be connected to the communication terminal device for radio communication and to provide a split bearer for the communication terminal device. The communication terminal device is configured to perform uplink transmission to an uplink transmission node among the plurality of nodes. The uplink transmission node is determined by an uplink transmission node determination process in which a node that provides the uplink transmission from the communication terminal device with lower latency among the plurality of nodes is determined as the uplink transmission node.

Abstract: Provided is a communication system capable of suppressing decrease in a transmission rate. An eNB communicates with a UE using a self-contained subframe. The self-contained subframe includes a downlink signal to be transmitted from the eNB to the UE, and an uplink signal to be transmitted from the UE to the eNB in response to the downlink signal. The uplink signal has a structure including an uplink control signal indicating information for controlling transmission of the uplink signal, and uplink user data to be transmitted before and after the uplink control signal. The eNB notifies the UE of a structure of the uplink signal. The eNB may predetermine scheduling for retransmission to retransmit the downlink signal, before performing initial transmission of the downlink signal.

Abstract: Provided is a communication system capable of suppressing decrease in a transmission rate. An eNB communicates with a UE using a self-contained subframe. The self-contained subframe includes a downlink signal to be transmitted from the eNB to the UE, and an uplink signal to be transmitted from the UE to the eNB in response to the downlink signal. The uplink signal has a structure including an uplink control signal indicating information for controlling transmission of the uplink signal, and uplink user data to be transmitted before and after the uplink control signal. The eNB notifies the UE of a structure of the uplink signal.

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: 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.

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: 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: 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 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 (902) in a subframe (901). The UE obtains, from the downlink control signal (902), information on a piece of user data (903) in the subframe (901), and the information (904) on the next reception timing. The UE transmits and receives the piece of user data (903) to and from the gNB. The information (904) on the next reception timing indicates a subframe (905) as the next reception timing of the UE. The UE receives a downlink control signal (906) in the subframe (905).

Abstract: Provided is a communication system capable of suppressing decrease in a transmission rate. An eNB communicates with a UE using a self-contained subframe. The self-contained subframe includes a downlink signal to be transmitted from the eNB to the UE, and an uplink signal to be transmitted from the UE to the eNB in response to the downlink signal. The uplink signal has a structure including an uplink control signal indicating information for controlling transmission of the uplink signal, and uplink user data to be transmitted before and after the uplink control signal. The eNB notifies the UE of a structure of the uplink signal.