Hitachi, Ltd.

Hitachi-kokusai Electric Inc.

Shigenori Hayase

Takashi Yano

Masaaki Shida

Keisuke Yamamoto

Tomoaki Ishifuji

Rintaro Katayama

Tomonori Yamamoto

Hirofumi Nakano

Kazuyuki Hori

Tetsuya Uda

Yoshimasa Kusano

Hirotake Ishii

Yunjian Jia

Shinji Murai

Satoshi Asamizu

Shigehiro Takashima

Mikio Kuwahara

Satoshi Tamaki

Masayuki Takase

Kenzaburo Fujishima

Nobuhiko Kikuchi

Masashi Naito

Tsuyoshi Tamaki

Masanori Taira

Yasutaka Morinaga

Yuji Oishi

A mobile-side IP address is translated into an intranet-side MAC address, and an IP address for an intranet is acquired. The present invention provides a network system for transferring a packet, including: a first network that controls transfer of data at a first layer; a second network that is connected to the first network and controls transfer of data at a second layer different from the first layer; and a translation device that translates an address between networks, in which the translation device translates the address of the first layer of the first network attached to data transferred from the first network to the second network into the address of the second layer of the second network.

Network system, communication control device, and communication control method

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

A macro base station includes a communication prohibited period setting unit of setting an uplink communication prohibited period to a user equipment belonging to the base station, and prohibits an uplink communication from the user equipment to a wireless communication base station per se during the uplink communication prohibited period. The user equipments belonging to the wireless communication base station per se and the second base station are divided into plural groups, and the uplink communication prohibited period is set to different time periods for the respective groups. Thereby, a communication characteristic is prohibited from being deteriorated at the second base station by an interference affected with the second base station separately from the first base station by the user equipment communicating with the first base station in the uplink communication.

Base station, system, and method of macro and pico base station interference coordination using uplink prohibition period

In MU-MIMO communication in which an AP (access points: wireless base station) receives signals sent from plural terminals at the same time and at the same frequency, combinations of terminal users and decoding order of the received signals are determined so that interference reduction advantage by applying SIC can be effectively obtained. The access point includes: a plurality of antennas; and a scheduler used for performing the MU-MIMO communication with a plurality of terminals at the same time and at the same frequency. The scheduler is configured to determine the combinations of the terminal users on the basis of uplink communication quality information of the plurality of the terminals when the MU-MIMO communication is performed, and to send the determined combinations of the users as schedule information.

Access point and interference control method

In a radio communication system where a base station provides blank time slots to avoid inter-cell interference, a decrease in throughput by an excess or shortage of blank time slots is prevented. This invention relates to a radio system that avoids interference in cooperation between base stations by providing blank time slots by a (first) base station. Other (second) base stations detect the number of served terminals affected by interference from the first base station that sets blank time slots, calculate required blank time slots so that the number of required blank time slots will increase with an increase in the number of terminals located in cell edges, and send a notification of the required blank time slots to the first base station. The first base station determines whether system throughput is anticipated to improve, based on the above notifications, and adjusts the length of blank time slots.

Base station and method of interference handling

A transmitting station having plural antennas includes: a control information calculation unit that calculates control information for use by plural receiving stations according to a multi-user MIMO data transmission scheme; a control information transmission parameter calculation unit that calculates a control information transmission parameter based on spatial channel related information; and a control information transmission signal creation unit that creates a control information transmission signal, using the control information transmission parameter and a pilot signal. A resource element mapping unit maps control information transmission signals onto corresponding resource elements for transmission. On the other hand, the receiving stations each include a control information acquisition unit that acquires plural pieces of control information signaled on the corresponding resource elements, acquire control information destined for each receiving station, and demodulate received signals.

Radio communication system, radio communication device, and radio communication method

A communication device includes pilot signal sending part and transmit power control part and holds a criterion value indicating target channel quality for mobile stations within the area covered by the base station. It creates quality data from reports from one or plural mobile stations, stores the quality data, creates a first representative value indicating average channel quality for the mobile station(s) from the stored quality data, and changes the transmit power depending on the result of comparison between the first representative value and the criterion value. It creates a second representative value indicating distribution of low channel quality from the stored quality data and updates the criterion value depending on the result of comparison between the second representative value and the criterion value.

Transmit power control method for reducing cellular interference in cellular radio communication system and radio base station device for implementing the same

In a MIMO wireless communication system, the transformation process synthesizes the eigenmodes having a large singular value (i.e. a high effective SNR) and the eigenmodes having a small singular value (i.e. a low effective SNR). Thereby, the former eigenmodes are converted into modes having suppressed effective SNR which do not require a large number of levels of modulation, and the latter eigenmodes are converted into modes having increased effective SNR instead. In a MIMO wireless communication system for eigenmode transmission, a large communication capacity is realized without increasing the number of levels of modulation even in a communication environment capable of achieving a high SNR.

MIMO wireless data communication system, MIMO wireless data communication method and MIMO wireless data communication apparatus

In a system in which a host and a plurality of terminals simultaneously communicate with each other under the SDMA scheme, transmission parameters to be used for generating frames for SDMA transmission to the respective terminals are adjusted in consideration of the transmission time durations necessary for transmission of other frames to be transmitted simultaneously with the first-mentioned frames, so that differences between the frame transmission time durations are reduced.

Wireless communication method, wireless communication apparatus and access point apparatus

In MIMO transmission between M transmission antennas and N reception antennas, a transmission signal vector is set as a vector having 2M elements comprising in-phase components and quadrature components of M complex signals, a reception signal vector is set as a vector having 2N elements comprising in-phase components and quadrature components of N complex signals, and a transfer matrix is set as a real matrix comprising 2N rows and 2M columns. Then, a transfer matrix containing IQ mismatch is obtained based on a training signal, thereby executing MIMO encoding and decoding. For learning of the transfer matrix, a training signal which has two linearly-independent signal points on a constellation for each of the transmission antennas is used. With such an arrangement, in MIMO transmission, IQ mismatch in a quadrature modulator and a quadrature demodulator can be compensated and a bit error rate can be improved.

Wireless data communication system and wireless data communication method

To detect phase mismatches between in-phase and quadrature signals of a quadrature demodulator. The phase mismatches can be detected using the signals obtained by removing high frequency components of output of a multiplier by a low pass filter, the output being the product of the in-phase signals of which low frequency components are removed by a first high pass filter by the quadrature signals of which low frequency components are removed by a second high pass filter.

Orthogonality detector, and quadrature demodulator and sampling quadrature demodulator using detector thereof

In a wireless communication system for communicating with a plurality of stations at the same point of time with the same frequency using a Space Division Multiple Access (SDMA), wireless resources are allocated by a first decision unit which evaluates performance of each station obtained when the SDMA is used and which determines periods of time to be allocated to groups of stations formed according to the SDMA technique. Using a first evaluation unit and a second evaluation unit to evaluate performance required by each station and each application, the first decision unit allocates the wireless resources to the stations. It is therefore possible that the wireless resources are efficiently allocated to the stations while preventing an event in which the wireless resources are excessive or insufficient for required quality of service.

Systems and methods for wireless communication using SDMA

A method for suppressing the peak-to-average power ratio (PAPR) while limiting deterioration in signal characteristics in wireless communication devices utilizing wireless communication methods (OFDM method, MIMO method) for multiplexing and sending multiple signals. A weight calculator unit sets a large weight for transmit signals whose channel quality is poor, relative to the weight of each base component based on the acquired channel quality. A peak detector unit detects the peak from the signal string after unitary conversion, and extracts a distortion component to apply for suppressing the peak. A peak suppression signal generation unit calculates the peak signal from the distortion component and weight of each base component, to add to each base component, and adds the peak suppression signal to each base component prior to unitary transformation.

Apparatus and method for peak suppression in wireless communication systems

To suppress the peak of the orthogonal multiplex transmission signal which is small in deterioration of the quality of the reception signal by generating the cancellation waveform in synchronization with the timing of the symbol of the transmission signal. There is provided a peak suppressing method that suppresses peaks of an orthogonally multiplexed signal whose orthogonality is ensured in given time units, the method comprising: a first step of detecting the peaks of the orthogonally multiplexed signal; a second step of generating a peak cancellation waveform based on the detected peaks of the orthogonally multiplexed signal; and a third step of removing the peak of the orthogonally multiplexed signal from the orthogonally multiplexed signal using the generated peak cancellation waveform. The second step comprises generating the peak cancellation waveform in said time units of the orthogonally multiplexed signal.

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Kodaira, Japan

Shigenori Hayase