Ntt Docomo, Inc.

Anass Benjebbour

Yoshihisa Kishiyama

Takahiro Asai

Yusuke Ohwatari

Satoshi Nagata

Kazuaki Takeda

Hitoshi Yoshino

Tomoyuki Ooya

Yukihiko Okumura

Junichiro Hagiwara

Koji Maeda

Yuuya Saitou

Kenichi Higuchi

Yuichi Kakishima

Sean Anthony Ramprashad

Tatsuo Furuno

Lan Chen

Huiling Jiang

Satoshi Suyama

Anxin Li

Yu Jiang

Xiang Yun

Wei Xi

Yang Lan

Ozgun Bursalioglu

Chunlin Yan

Masashi Iwabuchi

Tomoyuki Oya

A radio communication system includes a first radio base station having multiple antenna elements, and user equipment, wherein, for initial connection of the user equipment to the first radio base station, the first radio base station applies different precoding vectors to a downlink user common signal transmitted to all users located in or near a serving area of the first radio base station, and transmits the downlink user common signal while changing the applied precoding vector; wherein the user equipment selects a desired one of the precoding vectors applied to the downlink user common signal, and reports a selection result to the first radio base station, and wherein the first radio base station precodes a data signal addressed to the user equipment using the selected precoding vector and transmits the precoded data signal to the user equipment.

Radio communication system and radio base station apparatus

To perform appropriate AMC control even if low latency is required. A transmission apparatus includes: a reception section that receives channel quality information communicated between the transmission apparatus and a reception apparatus; a control section that determines one or more first candidates for a value indicating a coding and modulation scheme based on the channel quality information, determines one or more second candidates for a value indicating the coding and modulation scheme based on a parameter related to service quality required for a service communicated between the transmission apparatus and the reception apparatus, and selects a value included in both of the first candidates and the second candidates; and a transmission section that transmits transmission data using the coding and modulation scheme corresponding to the selected value.

Transmission apparatus, reception apparatus, and communication method

A radio base station making it possible to perform efficient scheduling of user terminals by reducing feedback information to be received from the user terminals is provided. A radio base station includes a position-related-information obtaining section configured to obtain position-related information indicating positional relationships among multiple user terminals. In addition, the radio base station includes a scheduler configured to determine user groups of the user terminals to be spatially multiplexed in the same time and frequency resources based on the position-related information obtained by the position-related-information obtaining section.

Radio base station

The present invention is designed to expand the coverage of reference signals in small cells that are arranged to overlap a macro cell, and, furthermore, reduce the interference between the small cells and improve the received quality of the reference signals in user terminals. The radio communication method of the present invention provides a radio communication method in a radio base station forming a small cell that is placed to overlap a macro cell, and includes the steps of generating a reference signal for measuring received quality, in a first transmission period in which beamforming is not executed, transmitting the reference signal in a narrower transmission bandwidth and with greater transmission power than in a second transmission period in which beamforming is executed, and allocating the reference signal to a band associated with information that is specific to each radio base station forming a small cell, and transmitting the reference signal.

Radio base station, user terminal and radio communication method

The present invention is designed to shorten the time that a user terminal takes to detect the common control/reference signals while coverage of the common control/reference signals transmitted from a small base station is secured. As the radio communication method of the invention, a radio communication method is provided in which beam forming information for forming transmission beams directed from the small base station to the user terminal are generated based on position-related information of the user terminal acquired by communication between the macro base station and the user terminal using a coverage carrier and position-related information of the small base station, and the small base station precodes at least one of a common control signal and a reference signal that are common in a small cell based on the beam forming information and transmits the precoded signal from a plurality of transmitting antennas using a capacity carrier.

Radio communication method, radio base station and radio communication system

A small base station executes radio communication using multiple antennas. There are set multiple antenna groups that each include all or a portion of the antennas and multiple antenna group patterns that each include at least one of the antenna groups. The small base station transmits reference signals with sequences that differ from one another between antenna groups that are included in the same antenna group pattern. A user apparatus receives the reference signals. Based on a reception result of the reference signals, a use antenna group pattern and at least one use antenna group that are to be used for transmission of a radio signal from the small base station are determined.

Communication control method, radio communication system, small base station, and user apparatus

A radio communication method is provided in which a local area base station apparatus, arranged in a wide area where a first carrier frequency is used and forming a local area that is narrower than the wide area, transmits a downlink signal, using a second carrier frequency, which belongs to a different frequency band from the first carrier frequency and which has a wider bandwidth than the first carrier frequency, the local area base station apparatus transmits a detection signal that is used to detect the local area base station apparatus in the mobile terminal apparatus, and the local area base station apparatus transmits the downlink signal for the mobile terminal apparatus with transmission power that is determined based on the path loss of the detection signal received in the mobile terminal apparatus.

Radio communication method, local area base station apparatus, mobile terminal apparatus and radio communication system

A user terminal selects small cells in a radio communication system in which a macro cell and small cells are arranged to overlap each other. In the cell selection method of the present invention, a macro base station to form a macro cell carries out the steps of determining the offset value to use in cell selection in a user terminal based on transmission property information of a second carrier in the small cell, and reporting the offset value to the user terminal. Also, the user terminal carries out the steps of measuring the received quality of reference signals from the macro base station and the small base station, receiving the offset value that is reported from the macro base station, and carrying out cell selection based on the received quality that is measured and the offset value that is received.

Radio base station, user terminal, cell selection method and radio communication system

The present invention is designed to make possible link adaptation that is suitable for future radio communication systems. A radio base station according to the present invention has a coding section that encodes downlink data for each of a plurality of user terminals, a modulation section that modulates the downlink data for each of the plurality of user terminals, and a transmission section that multiplexes the downlink data for each of the plurality of user terminals on a per subband basis, and transmits the downlink data for each of the plurality of user terminals by using transmission power that is allocated to each of the plurality of user terminals on a per subband basis.

A user apparatus according to an embodiment is provided. The user apparatus communicates with a base station in a wireless communication system. The user apparatus includes an obtaining unit configured to obtain resource allocation information in which downlink signal reception quality is associated with radio resources used for uplink signal transmission; a measurement unit configured to measure the downlink signal reception quality; and a transmission unit configured to determine a radio resource of the radio resources used for uplink signal transmission by comparing the resource allocation information with the measured downlink signal reception quality, and transmit an uplink signal by using the determined radio resource.

User apparatus, base station, and communication method

The present invention is designed to provide a radio base station, a user terminal, a radio communication method and a radio communication system of novel structures that can achieve improved throughput and system capacity. A radio base station transmits downlink reference signals that are specific to a plurality of transmission beams, a plurality of user terminals feed back coarse channel state information that is acquired by channel estimation, to the radio base station, the radio base station selects a plurality of user terminals to make feed back accurate channel state information based on the coarse channel state information, a plurality of user terminals that are selected feed back accurate channel state information, the radio base station determines a plurality of user terminals to non-orthogonal-multiplex, per transmission beam, based on the accurate channel state information, and non-orthogonal-multiplexes downlink signals, and a plurality of user terminals that are determined, after having canceled interference between the transmission beams by means of a linear filter, cancels downlink signals for other terminals, from the downlink signals that are non-orthogonal-multiplexed in each transmission beam.

Radio base station, user terminal, radio communication method and radio communication system

A user terminal includes a receiving section that receives a signal subjected to multiplexing in a power dimension in a given layer and that receives information about the multiplexing in the power dimension; and a signal processing section that demodulates a signal for the user terminal from the multiplexed signal based on the information about the multiplexing in the power dimension.

For each UE, a base station determines the number of streams for transmitting a data signal, performs different precoding on the data signal depending on the UE, and allocates different transmission powers to at least two UEs. The base station transmits streams addressed to the at least two UEs in a form in which these streams are non-orthogonally mixed, with transmission powers that are different for the UEs. For each of the streams addressed to these UEs, the base station estimates predictive indices for these UEs from channel state information determined by the UEs to which those streams are addressed, and, based on the predictive indices, allocates different transmission powers to those UEs such that the better the predictive index is, the lower the transmission power is.

User equipment and radio base station

The present invention is designed to provide a radio base station, a user terminal, a radio communication system and a radio communication method of novel structures that can improve the efficiency of the use of radio resources sufficiently. A plurality of user terminals feed back channel state information to a radio base station, the radio base station selects, from a plurality of candidate user sets and a plurality of power ratio sets, each of the candidate user sets indicating candidates of user terminals to be subject to non-orthogonal-multiplexing over a given radio resource and each of the power ratio sets indicating a transmission power ratio of downlink signals for the user terminals indicated in each of the candidate user sets, a candidate user set and a power ratio set to use in downlink signal transmission, based on the channel state information that is fed back, and transmits downlink signals for a plurality of user terminals indicated in the selected candidate user set using the transmission power ratio indicated by the selected power ratio set, and the selected candidate user set receive the downlink signals.

Radio base station, user terminal, radio communication system, and radio communication method

A user terminal includes a receiver that receives, from a radio base station, indication information to indicate whether or not uplink signals of a plurality of user terminals are non-orthogonal-multiplexed; a processor that switches between transmission power control methods based on the indication information; and a transmitter that transmits an uplink signal by using a switched transmission power control method.

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Tokyo, Japan

Anass Benjebbour