Softbank Corporation

Mitsukuni Konishi

Atsushi Nagate

Kenji Hoshino

Yoshichika Ota

Teruya Fujii

Koji Tashiro

Sho Nabatame

In an upper-airspace staying type communication relay apparatus that performs an MU-MIMO radio communication with plural terminal apparatuses located in a cell, it is intended to improve the communication quality of the entire cell and enhance the system capacity, while suppressing an increase in overhead in the terminal apparatus and the communication relay apparatus even if the number of terminal apparatuses located in the cell increases. The communication relay apparatus receives an uplink signal from each of plural terminal apparatuses via an array antenna, estimates angle information indicating a direction of the terminal apparatus for each of the plural terminal apparatuses, selects a terminal apparatus to be assigned to each of plural radio resources used for a downlink based on the estimation result of the angle information, calculates a downlink beamforming weight based on the estimation result of the angle information, and transmits a downlink signal to the terminal apparatus via the array antenna based on the beamforming weight corresponding to the terminal apparatus and the radio resources assigned to the terminal apparatus.

Massive MIMO for HAPS based on angle information on user apparatus

It is suppressed of a deterioration of a communication quality of a service link (SL), which is caused by an increase of signal attenuation in a propagation path of a feeder link (FL) between an aerial-staying type communication relay apparatus and a gateway (GW) station. A relay communication station of the communication relay apparatus comprises a FL communication section that performs a feeder-link radio communication with each of a first gateway station and a second gateway station corresponding to a first cell and a second cell which are adjacent to each other, a SL communication section that performs a radio communication with a terminal apparatus in each SL of the first cell and the second cell, and a control section that controls the SL communication section so that a shape of the second cell is changed to include a part or a whole of the first cell, when a radio communication quality in the FL propagation path with the first gateway station corresponding to the first cell is deteriorated or when the deterioration of the radio communication quality is predicted.

Multi-feeder link configuration in haps communication system and control therefor

In a mobile communication system using a mobile-type radio relay apparatus that forms a plurality of cells toward the ground or the sea while moving in an upper airspace, a deterioration in communication quality, which is caused by a Doppler shift of a reception signal due to a relative movement of a radio relay apparatus with respect to a terminal apparatus of each of a plurality of cells or a feeder station on the ground or on the sea, is suppressed. The communication system comprises a mobile-type radio relay apparatus that is disposed movably by flying in an upper airspace, forms a plurality of cells from an antenna at a predetermined altitude toward the ground or the sea, and performs a radio communication with a terminal apparatus located in each of the plurality of cells. The communication system comprises an estimation section for estimating a Doppler shift in at least one of a radio communication of a service link between the terminal apparatus located in the cell and the radio relay apparatus and a radio communication of a feeder link between the radio relay apparatus and a feeder station on the ground or on the sea, and a correction section for correcting a frequency of the at least one radio communication based on an estimation result of the Doppler shift.

Doppler shift correction in three-dimensional network

A base station, a communication system and a time synchronization method between base stations are provided, which are capable of performing a time synchronization with another base station using a downlink signal of the other base station cell in which the own cell is located, without stopping transmission of the own base station even during operation. A base station receives a downlink signal that includes a downlink signal including a synchronization signal transmitted from the other base station and a downlink wraparound signal transmitted from own base station, removes an interference of the wraparound signal from the downlink received signal, with respect to a predetermined subframe in which the downlink wraparound signal from own base station interferes with the synchronization signal of the base station, among subframes of the downlink signal including the synchronization signal of the base station, performs a time synchronization processing with the base station by detecting a synchronization signal timing of the base station based on the downlink received signal from which the interference of wraparound signal is removed.

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Tokyo, Japan

Mitsukuni Konishi