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 technology capable of securing satisfactory communication quality. A communication system includes a user equipment, and a base station configured to be connected to the user equipment to perform radio communication with the user equipment. The user equipment performs radio communication with a beam. When the user equipment detects a beam disappearance state being a state incapable of maintaining communication quality with the base station, the user equipment transmits a notification of the beam disappearance state with a beam having a wider half width than a half width before detection of the beam disappearance state.

Abstract: A signal is transmitted and received between a base station device and a communication terminal device that are included in a communication system, through a multi-element antenna including a plurality of antenna elements. At least one of the base station device and the communication terminal device includes a PHY processing unit that is a calibration unit that performs calibration of phases and amplitudes of beams formed by the antenna elements when the signal is transmitted and received. The PHY processing unit obtains a correction value for the phases and the amplitudes of the beams in the respective antenna elements so that the phases and the amplitudes of the beams are identical among the antenna elements, and performs the calibration based on the obtained correction value.

Abstract: In a communication system, a plurality of base stations includes an MeNB being a first base station, and a plurality of SeNBs to be connected to the MeNB. At least one of control plane data about control of communication and user plane data about a user is transmitted to and received from a user equipment (UE) via the first base station being the MeNB. The control plane data and the user plane data are contained in information provided by a core network about communication with the UE. The communication system can simplify processing of at least one of control plane data and user plane data when a communication terminal device communicates with a plurality of base station devices.

Abstract: Provided is a communication system capable of suppressing, under communication environment including a plurality of cells, degradation in communication quality and decrease in communication rate and communication capacity due to interference from the other cells. Each of the cells includes a plurality of antenna elements, and performs radio communication with a communication terminal device through the antenna elements. Each of the cells notifies the other cells of settings for measuring channel information on a channel for performing radio communication of its own cell. Each of the cells may notify a communication terminal device being served thereby of the settings for measuring the channel information of its own cell. Here, the communication terminal device measures the channel information based on the settings notified from each of the cells, and reports a result of the measured channel information to a corresponding one of the cells when the result satisfies a predetermined reporting condition.

Abstract: A narrow-bandwidth terminal device performs radio communication at a bandwidth narrower than a system bandwidth. The narrow-bandwidth terminal device in an idle state camps on a cell, and performs discontinuous reception of a signal transmitted from the cell. The terminal device also determines a reception condition of the signal, for example, whether the signal can be received. When it is determined that the signal cannot be received, the narrow-bandwidth terminal device moves out of a coverage area of the cell while continuing to perform the discontinuous reception. When it is determined that a discontinuous reception timer has been completed, the narrow-bandwidth terminal device continues to perform the discontinuous reception.

Abstract: A base station device is configured to set, for each communication terminal device, a radio format for signals transmitted to and received from the communication terminal device. The radio format is set for each communication terminal device in accordance with, for example, a type of use including a moving speed of the communication terminal device. The base station device may be configured to change the radio format for the communication terminal device based on the information about a change in the environment of a radio communication between the communication terminal device and the base station device and a change including the communication terminal device's location. The signals transmitted and received between the base station device and the communication terminal device include radio formats in which at least one of a length of a symbol of the signal and a length of a cyclic prefix in an OFDM scheme differs.

Abstract: Provided is a technology capable of securing satisfactory communication quality. A communication system includes a user equipment, and a base station configured to be connected to the user equipment to perform radio communication with the user equipment. The user equipment performs radio communication with a beam. When the user equipment detects a beam disappearance state being a state incapable of maintaining communication quality with the base station, the user equipment transmits a notification of the beam disappearance state with a beam having a wider half width than a half width before detection of the beam disappearance state.

Abstract: When being connected to a macro cell (S-MeNB) and a small cell (SeNB), a user equipment device performs a pre-handover process of disconnecting the connection with the SeNB before a handover process of switching a macro cell connected with the UE from the macro cell (S-MeNB) that is a moving source to a macro cell (T-MeNB) that is a moving destination along with moving of the UE, and after the handover process, performs a post-handover process of reestablishing the connection with the SeNB.

Abstract: Provided is a technology capable of securing satisfactory communication quality. A communication system includes a user equipment, and a base station configured to be connected to the user equipment to perform radio communication with the user equipment. The user equipment performs radio communication with a beam. When the user equipment detects a beam disappearance state being a state incapable of maintaining communication quality with the base station, the user equipment transmits a notification of the beam disappearance state with a beam having a wider half width than a half width before detection of the beam disappearance state.

Abstract: In a communication system, a plurality of base stations includes an MeNB being a first base station, and a plurality of SeNBs to be connected to the MeNB. At least one of control plane data about control of communication and user plane data about a user is transmitted to and received from a user equipment (UE) via the first base station being the MeNB. The control plane data and the user plane data are contained in information provided by a core network about communication with the UE. The communication system can simplify processing of at least one of control plane data and user plane data when a communication terminal device communicates with a plurality of base station devices.

Abstract: In a communication system according to the present invention, a UE and an MeNB perform both a direct communication and a communication through a SeNB. Along with moving of the UE, a handover process of switching the MeNB to which the UE is connected, from an S-MeNB to a T-MeNB is performed. The connection between the UE and the SeNB is maintained during the handover process. The UE starts transmitting data to the SeNB before a communication path between the UE and the MeNB is changed from a path formed by the S-MeNB and the UE to a path formed by the T-MeNB and the UE.

Abstract: In a communication system, a plurality of base stations includes an MeNB being a first base station, and a plurality of SeNBs to be connected to the MeNB. At least one of control plane data about control of communication and user plane data about a user is transmitted to and received from a user equipment (UE) via the first base station being the MeNB. The control plane data and the user plane data are contained in information provided by a core network about communication with the UE. The communication system can simplify processing of at least one of control plane data and user plane data when a communication terminal device communicates with a plurality of base station devices.

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: Provided is a technology capable of securing communication quality without providing an additional function such as phase correction. A base station device and a communication terminal device when operating as a transmitting device rotate inverse fast Fourier transform (IFFT) output, and copy a last portion of the rotated IFFT output to a head of the rotated IFFT output as a cyclic prefix (CP) to thereby generate a transmission signal so that there is no phase rotation at a head of a demodulation reception window set in a receiving device.

Abstract: The present invention has an object to provide a specific communication technology for realizing effective communication with a flying object in a communication apparatus including the flying object. The communication apparatus includes a first base station, a flying object including a second base station, and a mobile terminal to communicate with the second base station. The first base station notifies flying object specification information that is information indicating that the second base station is included in the flying object. When the flying object specification information is received, the mobile terminal sets a direction of a beam for detecting the second base station to a second direction that is a direction vertically upward compared to a first direction that is the direction of the beam in a case where the flying object specification information is not received.

Abstract: Provided is a technology capable of securing communication quality without providing an additional function such as phase correction. A base station device and a communication terminal device when operating as a transmitting device rotate inverse fast Fourier transform (IFFT) output, and copy a last portion of the rotated IFFT output to a head of the rotated IFFT output as a cyclic prefix (CP) to thereby generate a transmission signal so that there is no phase rotation at a head of a demodulation reception window set in a receiving device.

Abstract: The present disclosure has an object to provide a specific communication technology for realizing effective communication with a flying object in a communication apparatus including the flying object. The communication apparatus includes a first base station, a flying object including a second base station, and a mobile terminal to communicate with the second base station. The first base station notifies flying object specification information that is information indicating that the second base station is included in the flying object. When the flying object specification information is received, the mobile terminal sets a direction of a beam for detecting the second base station to a second direction that is a direction vertically upward compared to a first direction that is the direction of the beam in a case where the flying object specification information is not received.

Abstract: A signal is transmitted and received between a base station device and a communication terminal device that are included in a communication system, through a multi-element antenna including a plurality of antenna elements. At least one of the base station device and the communication terminal device includes a PHY processing unit that is a calibration unit that performs calibration of phases and amplitudes of beams formed by the antenna elements when the signal is transmitted and received. The PHY processing unit obtains a correction value for the phases and the amplitudes of the beams in the respective antenna elements so that the phases and the amplitudes of the beams are identical among the antenna elements, and performs the calibration based on the obtained correction value.

Abstract: A signal is transmitted and received between a base station device and a communication terminal device that are included in a communication system, through a multi-element antenna including a plurality of antenna elements. At least one of the base station device and the communication terminal device includes a PHY processing unit that is a calibration unit that performs calibration of phases and amplitudes of beams formed by the antenna elements when the signal is transmitted and received. The PHY processing unit obtains a correction value for the phases and the amplitudes of the beams in the respective antenna elements so that the phases and the amplitudes of the beams are identical among the antenna elements, and performs the calibration based on the obtained correction value.