Hitachi, Ltd.

Hitachi Communication Technologies, Ltd.

Hitachi Advanced Systems Corporation

Godo Kaisha IP Bridge 1

Kenzaburo Fujishima

Mikio Kuwahara

Masanori Taira

Katsuhiko Tsunehara

Koki Uwano

Yunjian Jia

Hitoshi Ishida

Koji Watanabe

Tomoaki Ishifuji

Rintaro Katayama

Atsushi Ogino

Go Ono

Takashi Yano

Satoshi Tamaki

Tsuyoshi Tamaki

Keisuke Takeuchi

May Takada

Toru Okamoto

Koji Meguro

Shinya Sasaki

Toshiyuki Saito

Hideya Yoshiuchi

Peng Yang

Shigenori Hayase

Kenichi Mizugaki

Hideya Suzuki

Hirotake Ishii

Zhisheng Niu

Yuichi Igarashi

Hajime Kanzaki

Jie Gong

Sheng Zhou

Yuanchen Ma

Hiroki Yamada

Masami Oonishi

Lu Geng

Yuta Muto

Kouki Uwano

Pinai Linwong

A computer system, which estimates a radio wave propagation characteristic in a space where a wireless communication system using structure data and system data is constructed, includes a computer having a processor and a storage apparatus and holds feature parameter information, which stores an entry that associates a parameter included in structure data, that is, a feature parameter which greatly contributes to an estimation result of the radio wave propagation characteristic in the space with a type of the space. When receiving a request for estimation of a radio wave propagation characteristic in a target space, the processor retrieves an entry associated with a type of the target space from the feature parameter information, and presents an interface to input a value of the feature parameter included in the retrieved entry as estimation structure data and an interface to input estimation system data.

Computer system, method for estimating radio wave propagation characteristic in space, and computer

It is provided a wireless communication system comprising base stations that transmit data to a terminal with cooperation by the base stations. The terminal communicates with the base stations. The terminal periodically transmits, to one of the base stations, information necessary for data transmission from a single base station out of the base stations. Each of the base stations determines whether the terminal needs data transmission through a cooperation among the base stations, and transmits a cooperation information transmission instruction to the terminal, which includes information necessary to execute the data transmission in order to cooperate among the base stations in the case where it is determined that the terminal needs the data transmission through the cooperation among the base stations. The terminal transmits the cooperation information to the base stations in a case of receiving the cooperation information transmission instruction.

Base station and wireless communication system

To prevent the switching time influences power saving performance and packet loss prevention performance, it is provided a wireless communication base station for communicating with a terminal, comprising: a plurality of baseband signal processing units for performing baseband signal processing; a baseband allocation unit for allocating the baseband signal processing to the plurality of baseband signal processing units; and a linear processing unit for composing signals processed by the plurality of baseband signal processing units. The baseband allocation unit selects, for each data block, a baseband signal processing unit to which the baseband signal processing for the each data block is to be allocated out of the plurality of baseband signal processing units. Each of the plurality of baseband signal processing units performs the allocated baseband signal processing. The linear processing unit composes, by means of linear calculation, the signals processed by the plurality of baseband signal processing units.

Wireless communication base station and wireless communication method

The present invention is directed to achievement of a data transmission control to cause base stations to cooperate with one another, taking into account efficient use of radio resources. A wireless communication system, which is an aspect of the present invention, includes: a first base station; a second base station connected via a wired network; and a wireless communication terminal that conducts at least one of single data transmission in which a single base station transmits data and cooperative data transmission in which a plurality of base stations cooperate to transmit data. The base stations notify the wireless communication terminal of a condition indicating a case where the cooperative data transmission can be performed. If the communication quality of the propagation path meets the condition, the wireless communication terminal transmits, to the base stations, information that is required for the cooperative data transmission.

Wireless communication system with multiple base stations cooperating to transmit data

A base station performs an association between frequency range and combinations of a plurality of base stations including an local base station to notify a terminal of the association. According to the notified association, the terminal, for each frequency, calculates quality of communication with one base station or quality of communication with the combination of the plurality of base stations. The base station and the control station determine the base station/the plurality of base stations that communicate with the terminal, the wireless resource and the transmission scheme, based on the result. Further, the base station selects whether to notify an entirety of or a part of the association to the terminal using positional information of the terminal. Since the association information that is unnecessary for the terminal is not communicated, it is possible to further lighten the load of control.

Wireless communication system, base station, and wireless communication method

A method of wireless communication for communication between a base station and a plurality of terminal apparatuses, the method including: dividing an available frequency into a plurality of segments and notifying control information to the terminal apparatus, the control information including setting of a segment of the plurality of segments, communication quality of which will be fed back by the terminal apparatus, and cancellation of a segment of the plurality of segments, communication quality of which has already been fed back from the terminal apparatus; and feeding back communication quality related to a predetermined segment to the base station in accordance with the control information by the terminal apparatus.

Broadband wireless communication resource assigning method, base station apparatus and terminal apparatus

A base station broadcasts a message saying that transmittable ranging codes are limited by antenna IDs to limit antennas and the ranging codes to be searched, thereby reducing a processing load of the search. In a cellular radio communication system in which a base station device is connected to plural antennas, and antenna IDs for identifying the antennas are transmitted from the respective antennas, the base station device broadcasts a message saying that a group of ranging codes transmittable by a terminal device is limited by the antenna IDs, the terminal device receives the message, identifies the antenna ID, selects the ranging code from the group of the ranging codes corresponding to the antenna ID, and transmits the selected ranging code.

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

In an environment in which a macro base station and a low transmission power base station exist, the ratio of the interference reduction time period of the macro base station is optimized, and the throughput of the low transmission power base station is improved, while minimizing a reduction in throughput. The macro base station causes a high interference to other base stations and one or a plurality of low power nodes (LPN) subjected to interference from the macro base station. The macro base station sets first and second data transmission time periods and then determines the ratio of the second time period and the pattern of the first time period and the second time period based on communication quality in the first time period and communication quality in the second time period of the macro base station and the LPN.

Radio communication system, base station, and interference management scheme

Disclosed are a communication control device, a communication control method and the system thereof, which provide efficient multi-base station joint services in a mobile communication system using dynamic clustering. Optimal base station clustering is chosen according to the communication state between a terminal and each base station. The communication control device connects with multiple base stations through a network, and clusters the multiple base stations dynamically so that the clustered multiple base stations can provide services for the mobile terminal in union. The communication control device comprises: an interface, connecting with multiple base stations, receiving channel state information related to the mobile terminal from each base station; a memory unit, storing the channel state information of the mobile terminal received from the interface; a control unit, clustering each base station dynamically according to the channel state information of the mobile terminal stored in the memory unit.

Device and method for base stations dynamic clustering in mobile communication

To reduce an uplink interference in a network with a first base station of a large output and a second base station of a small output. Detecting the interference, the second base station urges the first base station to hand over a terminal causing it to the second base station. Multiple base stations and one or more terminals exist in this system, each terminal connects with one base station, and a serving base station is changed according to a communication state of each terminal. If the different second base station other than the first base station to which the terminal connects detects a large interference, the second base station will multicast transmit information for urging handover to the base stations except itself. The base station having received the information specifies a terminal giving the interference to the second base station, and makes it to be handed over thereto.

Wireless communication system and base station

To secure a constant level or more of radio communication quality for each user equipment performing radio communication with a base station apparatus, and to increase the number of user equipment which the base station apparatus can accommodate under a condition of assuring the radio communication quality. In a radio communication system where there exist a base station apparatus having multiple antennas and user equipment for performing radio communication with a first antenna group including one or more of the antennas, the first antenna group is made configurable for each user equipment individually, and addition/deletion of the antenna to/from the first antenna group is performed based on the communication quality of each user equipment so that the number of antennas within the first antenna group may be minimized within a range satisfying a required value of the communication quality between the base station apparatus ad the user equipment.

Radio communication system, base station apparatus, and radio communication method

Provided is a wireless communication system which includes a wireless communication unit using plural frequency bands and plural antennas. The system changes the transmission power of each antenna, based on the interference of each of the frequency bands from the neighbor base station along the antenna direction. The system estimates the number of antennas necessary for transmission in response to a user requirement, and determines a necessary antenna in accordance with the antenna direction in which the terminal is located, and further changes the transmission power of each antenna.

Wireless base station for controlling antenna transmission power

In the case where a base station other than of a distributed antenna system provides a time or frequency at which a transmitted power is low, an antenna group configuration unit estimates a communication area of a mobile station using an uplink reference signal that the mobile station transmits, calculates an inter-system interference power for the communication area of each mobile station based on a received power of the out-of-system base station that the each mobile station reports, calculates the inter-system interference power to each of antennas by averaging the inter-system interference powers that the multiple mobile stations report, and decides antennas that form an antenna group according to magnitudes of the calculated inter-system interference powers.

Distributed antenna system, allocation of distributed antennas, base station

A discontinuous change in a transmission timing in a time domain, which is caused by a transmission timing adjustment processing of an OFDMA uplink or the like, brings about a discontinuous rotation of a signal phase in a frequency domain, resulting in reduced communication quality. A wireless communication system of the present invention allows the signal phase of the frequency domain in a receiving station to be continuous before and after the timing adjustment processings by controlling a signal sequence in a transmission signal after conversion in the time domain in synchronization with the timing adjustment processing.

Timing adjustment method, receiving station, and transmitting station in wireless communication system, and wireless communication system

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Kokubunji, Japan

Kenzaburo Fujishima