Hitachi, Ltd.

Other

Hitachi Computer Engineering Co., Ltd.

Tomoaki Ishifuji

Takashi Yano

Mikio Kuwahara

Nobukazu Doi

Masaaki Shida

Atsushi Ogino

Katsuhiko Tsunehara

Hidehiko Jusa

Shuichi Adachi

Eiichi Amada

Yoshihiro Takiyasu

Hideya Suzuki

Genichi Ishii

Kenzaburo Fujishima

Takeshi Saitoh

Tsuyoshi Tamaki

Shigenori Hayase

Satoshi Tanaka

Kenji Nagai

Katsuhiro Furukawa

Shinji Murai

Kazuko Hamaguchi

Shinji Nishimura

Koji Watanabe

Toru Miura

Toshikazu Nishino

Takaki Uta

Kiyoshi Takahashi

Masato Hirai

Masahiro Takiguchi

Hisanobu Dobashi

Kenichiro Orita

Tatsuya Hirata

Takaharu Aoyama

Hiromi Sato

Shigeru Date

Ryouzo Yoshino

Kouji Watanabe

Gen'ichi Ishii

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

By using the delay profile created by delay profile creating sectionand the first threshold valuereceived from the first threshold value calculation, the first threshold value timing detection sectionselects only the earliest receive timing exceeding the first threshold value, from all the timing that the correlation value in the delay profile becomes a maximum. By using the receive timing and the second threshold valuereceived from the second threshold value calculation section, reference timing calculation sectionselects the reference timing required for calculating the receive timing for the incoming wave of the minimum propagation delay time. The timing delayed by previously set timing behind said reference timing is sent from receive timing calculation sectionas the receive timingof the incoming wave of the minimum propagation delay time.

Method for measuring distance and position using spread spectrum signal, and an equipment using the method

At least three base stations transmit a specific signal pattern at given intervals. This allows a mobile station that received this signal pattern to locate itself by using the positional information about the base stations, sending timing (or information on phase shift from the reference time) of each signal pattern from the base stations, and signal pattern receiving time information. At least one of the above base stations changes the sending timing of the signal pattern. On this occasion, the mobile terminal or station is notified of the altered reference time offset (or information on phase shift from the reference time) of the sending timing or updated sending timing of the signal pattern.

Method of providing location service using CDMA-based cellular phone system, a method of measuring location and location system

Disclosed is a wireless communication system capable of performing demodulation at the receiving side without substantially deteriorating BER characteristics, regardless of carrier frequency error existing among plural wireless communication systems in SDMA of uplink. The wireless communication system includes plural antennas; a MIMO processor that decomposes a reception signal the plural antennas received from plural transmitters into transmission signals transmitted from the respective transmitters; a FFT processor that carries out OFDM demodulation; and a demapping unit that obtains data from signals which were previously converted into sub-carrier signals by the FFT processor, in which the MIMO processor is installed ahead of the FFT processor for sake of the processing sequence of a receive signal, and even though a carrier frequency offset exists in the reception signal MIMO processing is performed prior to OFDM demodulation to split the reception signal from plural transmitters.

Radio communication device

By using the delay profile created by delay profile creating sectionand the first threshold valuereceived from the first threshold value calculationthe first threshold value timing detection sectionselects only the earliest receive timing exceeding the first threshold value, from all the timing that the correlation value in the delay profile becomes a maximum. By using the receive timing and the second threshold valuereceived from the second threshold value calculation sectionreference timing calculation sectionselects the reference timing required for calculating the receive timing for the incoming wave of the minimum propagation delay time. The timing delayed by previously set timing behind said reference timing is sent from receive timing calculation sectionas the receive timingof the incoming wave of the minimum propagation delay time.

A system and method are provided for wireless communication. In one example, a wireless communication system that enhances total system throughput is provided. The system performs parallel data transmission from a plurality of access points to a plurality of user terminals. On terminals with power control function, their transmit power can be set to minimize interference. The wireless communication system comprises a management server which performs centralized management of time of access-point-to-terminal packet transmission, access points, and user terminals that perform data transmission, according to transmission time control information from the management server. Transmit queues for measuring downlink traffic and receive queues for measuring uplink traffic are provided on the access points or the management server. The system determines uplink and downlink periods from the transmit and receive queue lengths. The system also controls the access points and user terminals to transmit for the determined periods. Consequently, packet collision due to transmission from a terminal that interferes with neighboring terminals is eliminated. Thus, system throughput is enhanced.

System and method for wireless communication using a management server and access points

A time slot for a connection request sent from a mobile station includes the mobile station ID and the application discrimination word of the object application for which the mobile station requests the connection. By referring to the database, a base station assigns a MDC preferentially to a mobile station issuing a connection request for calling a high priority application. The base station monitors the MDCs used for ongoing communications. If a MDC assigned to a mobile station does not satisfy a predetermined radio communication quality, other MDCs for lower priority application are freed and reassigned to the mobile station. A plurality of MDCs including the reassigned MDCs into which the same contents are encapsulated are transmitted to the mobile station.

Digital radio communication system for multi-application

A wireless communication system has no limitation in the number of AP antennas and UT antennas, and determines the parallel-communication data units to be a maximum value of MIMO communication, such that it provides a MIMO-SDMA wireless data communication system having superior transmission characteristics. The MIMO-SDMA wireless data communication system includes a single AP (Access Point) and U UTs (User Terminals) communicating with the AP using the same frequency signal at the same time. The UT includes the SDMA reception (Rx) processor, and synthesizes Rx signals of antennas, such that it controls the number of Rx data units. By the control of the number of Rx data units, the communication system controls the number of parallel-communication data units to be equal to a maximum value capable of being implemented by the MIMO-SDMA wireless data communication. The AP informs the UTs of a coefficient matrix required for the SDMA Rx process, prior to transmitting actual data.

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

The code system is realized by that a plurality of waveforms A and B each having duty ratios of 50% in which only any one of a rising edge and a falling edge is present are combined with each other, and '1' and '0' are allocated to the combined waveform. In accordance with the present invention, both a clock and data can be transmitted at the same time, and can be readily demodulated without using a complex PLL circuit. As a trial manufacture according to the present invention, the demodulator could be realized which could allow variations contained in an input frequency by more than 1 digit under operating voltage of 2 V. The effectiveness of this patent could be confirmed.

Communication method of contactless ID card and integrated circuit used in communication method

A charging system for use in a network composed of wireless terminals with a repeater function. As each terminal with a repeater function receives a communication session start request from a user terminal, it searches for a destination user terminal; when it finds the destination user terminal, it transfers the signal sent from the requesting user terminal to the destination user terminal without the mediation of base stations. The information about the amount of data thus transferred or communication time for transferring data is sent to the charging system which is under the control of the communications service provider concerned.

Charging method and terminal equipment in the information and communication network system

A contactless IC card having an antenna, a transmit/receive circuit for recovering data (clock) and electric power from a carrier signal received by the antenna, a logic circuit operated with the electric power supplied thereto from the transmit/receive circuit, and a memory. The transmit/receive circuit has a rectifier circuit for outputting data (clock) and rectifier circuits for electric power in such a manner that the carrier signal is inputted to each of the rectifier circuit for outputting data (clock) and the rectifier circuit for electric power. With this configuration, high frequency matching can be optimized separately for the rectifier circuit for outputting data (clock) and the rectifier circuit for electric power. It is also possible to separately optimize adjustments to a voltage of recovered data (clock) and a recovered supply voltage.

Contactless IC card

By using the delay profile created by delay profile creating sectionand the first threshold valuereceived from the first threshold value calculation section, the first threshold value timing detection sectionselects only the earliest receive timing exceeding the first threshold value, from all the timing that the correlation value in the delay profile becomes a maximum. By using the receive timing and the second threshold valuereceived from the second threshold value calculation section, reference timing calculation sectionselects the reference timing required for calculating the receive timing for the incoming wave of the minimum propagation delay time. The timing delayed by previously set timing behind said reference timing is sent from receive timing calculation sectionas the receive timingof the incoming wave of the minimum propagation delay time.

An offset measuring method according to the present invention accurately measures a transmitting time offset of a base station. The offset measuring method for receiving signals from the radio base station and measuring the transmitting time offset of the radio base station includes the steps of calculating estimated values of transmitting time offset based on signals received at a plurality of observation points and selecting a minimum from the estimated offsets to determine the selected minimum value as transmitting time offset of the radio base station.

Method and apparatus for measuring transmitting time offset of a base station

A positioning method, which is related to a technique to measure a correct position of a terminal by preventing time required for the position measurement, of calculating a position of a receiver according to signals from a plurality of wireless transmitters includes a first step of measuring propagation delay time of the signal from each of the wireless transmitters and calculating a position of the receiver and a standard deviation about measuring distance error, a second step of calculating a positioning error of the receiver a third step of determining, according to the positioning error calculated by the second step, wireless transmitters in directions nearer to a direction in which the positioning error is large, and a fourth step of re-detecting signals from the wireless transmitters determined by the third step and thereby re-calculating the position of the receiver.

Growing community of inventors

Tokyo, Japan

Tomoaki Ishifuji