Ntt Docomo, Inc.

Polaris Wireless, Inc.

Jiyun Shen

Yasuhiro Oda

Yukihiko Okumura

Satoshi Suyama

Tamami Maruyama

Takahiro Asai

Ngoc Hao Tran

Hiromasa Fujii

Tomoyuki Ohya

Tatsuo Furuno

Hidetoshi Kayama

Scot Douglas Gordon

Hirohito Suda

Tarun Kumar Bhattacharya

Tatsunori Obara

Hitoshi Yoshino

Hassan Mohamed El-Sallabi

Kosei Takiishi

Takahiro Kubo

Takefumi Yamada

Tatsuki Okuyama

Yoshifumi Morihiro

Tetsuro Imai

Hidekazu Murata

Hassan Mohamed Ei-Sallabi

Fujii Hiromasa

A radio transmitting station includes: multiple transmitting antenna elements configured to transform electrical signals into radio waves and emit the radio waves; a precoder configured to control a beam direction of the radio waves to be emitted from the multiple transmitting antenna elements by giving precoding weights to the electrical signals to be supplied to the multiple transmitting antenna elements; and at least one power adjuster configured to adjust power of an electrical signal that is to be supplied to at least a portion of the multiple transmitting antenna elements, such that differences between powers of the electrical signals to be supplied to the multiple transmitting antenna elements are reduced.

MIMO transmission scheme using multiple antennas in a radio communication station

A radio transmission station gives beamforming weights to electrical signals to control directions of radio-wave beams emitted from transmitting antennas. The radio transmission station generates a beam-discovery signal (BDS) that enables a radio reception station, after the radio reception station receives the beams, to identify the directions of the beams, and emits the BDS beams in multiple directions. The radio transmission station determines, based on at least one of the surroundings of the radio transmission station and a situation of the radio reception station, an arrangement pattern of multiple resource points to which the BDS is mapped. Based on information that is reported from the radio reception station and indicates a suitable direction among the directions of the beams, the radio transmission station determines a suitable beamforming weight that is to be given to a data signal addressed to the radio reception station.

Radio transmission station and radio communication network

To suppress reduction in system performance for mobile communications (group mobility) in a plurality of terminals existing inside the same moving object, a radio communication system for a plurality of user terminals existing inside a moving object and a radio base station is described. The user terminal receives a signal transmitted from the radio base station, and transmits the signal transmitted from the radio base station to a common reception apparatus disposed inside the moving object. The common reception apparatus detects a signal for each user terminal, based on signals transmitted from the plurality of user terminals, and transmits the detected signal to each user terminal. The user terminal receives the signal for the user terminal detected in the common reception apparatus to demodulate. Thus, for group mobility, it is possible to cancel interference among user terminals to improve the multiplexing effect, while suppressing communication overhead.

Radio communication system, common reception apparatus and user terminal

The present invention is designed so that a radio base station controls base station parameters dynamically, in accordance with changes in the surrounding propagation environment. The radio base station according to the present invention has a surrounding environment information acquiring section that acquires surrounding environment information, which is information about the environment in a service area, a propagation environment information extraction section that extracts propagation environment information, which is information about electric wave propagation, based on the surrounding environment information, and a base station parameter generating section that generates base station parameters, which are information about the control of electric waves to transmit and receive, based on the propagation environment information.

Radio base station, radio communication system and radio communication method

A number Lof receive beamforming circuits provided in a receive beamformer execute receive beamforming (N/L) times with respect to a received signal vector received by Nreception antennas A, thereby generating a receive beamforming (BF) output vector having Nreceive BF output components. A calculation processor calculates a reception power for each of the Nreceive BF output components, selects Lreceive BF output components in decreasing order of reception power, and determines a suitable receive BF weight matrix including Lreception orthogonal BF weight vectors corresponding to the selected receive BF output components.

Radio communication control method and radio communication system

To improve system performance for mobile communications (group mobility) in a plurality of terminals existing inside the same moving object, a radio base station, which forms a cell on a moving path of a moving object to communicate with a mobile station provided in the moving object using beam forming, is provided with a transmission section that transmits a plurality of acquisition signals applied with different beam forming weights respectively to at least an edge region of the cell formed on the moving path of the moving object, and a control section that controls a beam forming weight to apply to a data signal transmitted to the mobile station, based on information notified from the mobile station receiving an acquisition signal.

Radio base station, mobile station and radio communication method

To suppress complication of transmission/reception processing even in the case where a user terminal supports a plurality of bandwidths, or the case where the terminal concurrently connects to a plurality of radio communication systems with different usage frequencies, a user terminal, which communicates with a radio base station for forming a wide-area cell and anther radio base station for forming a narrow-area cell in a radio communication system where the narrow-area cell is provided inside the wide-area cell, is provided with a reference signal generating section that generates a sampling frequency of a baseband signal of the wide-area cell as a reference signal, a frequency adjusting section that converts a frequency of the reference signal by n/m times, and a baseband processing section that uses a frequency subjected to frequency conversion as a sampling frequency of a baseband signal of the narrow-area cell.

User terminal, radio base station and radio communication method

In order to make full use of the performance of a Massive-MIMO-applied communication system, provided is a base station apparatus for controlling a transmission direction of a transmission beam for a synchronization signal used in cell search by beamforming using a plurality of antenna elements. The base station apparatus has a synchronization signal processing section () that generates the synchronization signal including information to identify the transmission beam for the synchronization signal and changes a beamforming weight for the synchronization signal at every given time interval; and a transmission section () that transmits the synchronization signal generated with the beamforming weight in downlink.

Synchronization signal transmitting method and base station apparatus

A mobile communication system that includes a first communication system, which features a user terminal that is present in a moving object, a first radio base station that forms a cell in the moving object, and a first core network that is connected with an external network, and a second communication system, which features a radio mobile station that is provided in the moving object, a second radio base station that forms a cell on the path of the movement of the moving object, and a second core network that is connected with the second radio base station. The first radio base station and the radio mobile station are connected via a user-plane interface and a control-plane interface between the radio base stations and the core networks.

Mobile communication system, radio base station, radio mobile station and mobile communication method

A communication control method includes: for each of plurality of receivers UE, calculating excluding channel matrices that include a plurality of equivalent channel matrices acquired by multiplying a transmit BF weight matrix corresponding to that receiver UE by each of a plurality of channel matrices corresponding to receivers UE other than that receiver UE, acquiring a first eigenvector that is included in a right-singular matrix obtained from single value decomposition of the excluding channel matrices, the first eigenvector corresponding to a noise subspace of the excluding channel matrices, acquiring a second eigenvector that is included in a right-singular matrix obtained from single value decomposition of a product of an equivalent channel matrix including the transmit BF weight matrix corresponding to that receiver UE and the first eigenvector, the second eigenvector corresponding to a signal subspace of the product, and obtaining a precoding matrix corresponding to that receiver UE by multiplying the first eigenvector by the second eigenvector.

The present invention is designed so that, in a communication system to employ massive MIMO, data signals to which beamforming is applied can be transmitted adequately. A radio base station transmits a data signal to a user terminal by applying beamforming using a plurality of antenna elements, and has a determining section that determines the type of a weight to apply to the data signal for beamforming, a generating section that generates a reference signal which the user terminal uses in channel estimation, a weight control section that controls weights to apply to transmitting signals, and a transmitting section that transmits the data signal and the reference signal, and the weight control section determines whether or not to apply a weight to the reference signal based on the type of the weight.

Radio base station, user terminal and radio communication method

A radio relay station is arranged on a moving conveyance. The radio relay station receives downlink radio signals from a stationary base station fixed outside the conveyance, and transmits to destination user equipments in the conveyance downlink radio signals resulting from the downlink radio signals transmitted from the stationary base station. In addition, the radio relay station receives uplink radio signals from multiple user equipments in the conveyance, and transmits to the stationary base station uplink radio signals resulting from the uplink radio signals transmitted from the multiple user equipments. The radio relay station receives from the multiple user equipments auxiliary radio signals indicating a downlink radio signal which the stationary base station has transmitted, detects, within a result of reception of the auxiliary radio signals, a downlink radio signal addressed to a user equipment in the conveyance, and transmits the downlink radio signal to the user equipment.

Radio relay station

To actualize frequency synchronization with each of radio communication systems while suppressing increase in circuit scale of a user terminal in an environment in which the user terminal concurrently communicates with a plurality of radio communication systems with different frequencies, a radio base station of the present invention is a radio base station for forming a narrow-area cell to communicate with a user terminal in a radio communication system where the narrow-area cell is provided inside a wide-area cell, and has a carrier frequency synthesizer that generates a carrier frequency of the narrow-area cell based on a wide-area radio signal transmitted from a radio base station for forming the wide-area cell, and a sampling frequency synthesizer that generates a sampling frequency of a baseband signal of the narrow-area cell based on the wide-area radio signal.

The present invention is designed to allow a communication system employing massive-MIMO to optimize its performance. A mobile station apparatus transmits a synchronization signal by controlling the transmission direction of the transmitting beam for the synchronization signal by means of beamforming using a plurality of antenna elements, and has a synchronization signal processing section () that generates the synchronization signal including identification information of the mobile station apparatus, and changes the beamforming weight for the synchronization signal at predetermined time intervals, and a transmitting section () that transmits the synchronization signals generated in accordance with each beamforming weight on the uplink.

Synchronization method, mobile station apparatus and base station apparatus

To reduce a bandwidth required for an optical transmission path () in a base station system including an RAU () for performing MIMO transmission using a plurality of antenna elements and a BBU (), in a communication control method of the present invention, the BBU () transmits antenna weight coefficient information indicative of antenna weight coefficients of a plurality of antenna elements () and a transmission signal, and the RAU () multiplies the transmission signal from the BBU () by each of the antenna weight coefficients to generate weighted signals of the plurality of antenna elements (), and transmits the weighted signals from the plurality of antenna elements ().

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Yokohama, Japan

Jiyun Shen