Hitachi, Ltd.

Hitachi Communication Technologies, Ltd.

Godo Kaisha IP Bridge 1

Koki Uwano

Kenzaburo Fujishima

Rintaro Katayama

Keisuke Takeuchi

Satoshi Tamaki

Mikio Kuwahara

Masanori Taira

Tomonori Yamamoto

Takashi Yano

May Takada

Go Ono

Shinya Sasaki

Katsuhiko Tsunehara

Toshiyuki Saito

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

A radio communication system using an orthogonal frequency division multiplexing system, including: a baseband unit; and one or plural remote radio units coupled with the baseband unit through an interface; wherein the baseband unit includes a first sample frequency conversion part that performs a first sample frequency conversion processing that down-samples a transmitting signal transmitted through the interface, wherein the remote radio unit includes a second sample frequency conversion part that performs a second sample frequency conversion processing that up-samples a signal received through the interface, and wherein the baseband unit further includes an inverse fast fourier transform part that generates the transmitting signal by an inverse fast fourier transform, and a transmitter characteristic compensation part that conducts frequency characteristic compensation of the first sample frequency conversion processing and the second sample frequency conversion processing for a signal that has not been subjected to the inverse fast fourier transform.

Transmitting device, receiving device, and signal processing method in radio communication system

Ameliorate deterioration in quality of communication caused by intercell interference with respect to a multicarrier communications protocol, such as OFDM. A method of positioning an error correction-coded signal is changed with a data symbol that is transmitted simultaneously with a pilot signal and a data symbol that is not simultaneous with the pilot symbol. Else, a modulation protocol is changed with a data symbol that is transmitted simultaneously with a pilot signal and a data symbol that is not simultaneous with the pilot symbol. It would further be permissible to lower either a signal amplitude or a power level of a data symbol that is transmitted simultaneously with a pilot signal.

Signal mapping method and communication device

A method for radio resource control is carried out in a radio communications system including multiple base stations. In this method, a radio resource that can be used by the base stations is divided into multiple first radio resources on the frequency axis. Then one or more of the first radio resources are allocated to a second radio resource for initially transmitting a packet and the other first radio resources are allocated to a third radio resource for retransmitting the packet.

Method for radio resource control and base station using the same

A base station is connected to wired and wireless networks to send a call that is received from the wired network to the wireless network at a predetermined quality of service (QoS), select one or more combinations of a set of modulation and coding scheme, and a radio resource amount that are associated with a QoS set in a newly incoming call, determine the radio resource amount that is equal to or less than a amount of the unassigned radio resources, assign, to the newly incoming call, the combination that is associated with the determined radio resource amount and the QoS set in the newly incoming call, reduce the radio resources assigned to the ongoing call without changing the QoS, and assign, to the newly incoming call, an amount of radio resources released from the ongoing call and modulation and coding scheme associated with this released radio resource amount.

Base station and access control method for cellular wireless communication

Conventionally, different HARQ processesand(subframes Tand T) transmit data packets B and D, respectively. One data packet corresponds to one process and is retransmitted as necessary one by one on a process basis, degrading the usage efficiency of frequency and time resources. To solve this problem, downlink data packets B and D, when needed to be retransmitted, are spatially multiplexed in the different HARQ processesand. The data packets are simultaneously retransmitted to the same terminal as process(subframe T).

Base station, terminal and wireless communication system

A radio communications system includes at least one terminal communication unit having one antenna that conducts a radio communication with a plurality of terminals; and at least one baseband modem that generates and decrypts a data signal, a cell being configured by at least one of the antenna, wherein the baseband modem divides a radio frequency band used for the radio communication into two or more subbands, generates and decrypts the data signal specific to each of the divided subbands, and allocates the data signal specific to the subband to the terminal communication unit, and wherein the terminal communication unit receives the data signal specific to the subband generated by the baseband modem, and forms the cell of each the subband by the data signal specific to the received subband.

Radio communications system

A signal frequency of an interface signal between a baseband unit and a remote radio unit is decreased by downsampling, and the strain of the signal caused by downsampling is compensated for each subcarrier before an IFFT during transmission, and after FFT during reception.

A wireless communication method in which a base station and a wireless terminal communicate, including: an operation at which a first and a second base station transmit, for each beam area, a pilot signal including identification information to identify the base station and the beam area, in a beam pattern; an operation at which the wireless terminal obtains received power of each pilot signal; an operation at which the wireless terminal causes one of the beam areas of the first base station to be a desired wave beam area, and determines two data rates for requiring to the base station: one of the data rates being a first data rate used in a case that interference from the second base station is relatively high and another of the data rates being a second data rate used in a case that the interference from the second base station is relatively low.

Wireless communication method

A non-terminated packet is transmitted, by utilizing a spatial layer responded with an ACK, which is assumed as a released layer. Alternatively, a non-terminated packet is transmitted by using a released layer and an original spatial layer in combination. Alternatively, a new packet is transmitted in a released layer by utilizating time till termination of transmission of a non-terminated packet. A wireless communication system effectively utilizing a released layer, a terminal and a base station.

Wireless communication system, terminal and base station

Provided is a wireless base station comprising: a power control unit, a reference information acquisition unit and a reference information storing unit, wherein the wireless base station comprises a first control signal receiving unit for receiving a first uplink control signal used by a mobile station connected to the wireless base station and for requesting the power control unit to control the transmission, and a second control signal receiving unit for receiving a second uplink control signal used by a mobile station connected to the neighbor base station and for requesting the power control unit to control the transmission power, and wherein the power control unit controls the transmission power of the downlink signal based on the request to control the transmission power from the first control signal receiving unit and the request to control the transmission power from the second control signal receiving unit.

When a receiving apparatus which employs a OFDM-based cellular wireless communication scheme detects as an excessive signal for each frame, the signal having signal intensity exceeding a reference value after a Fourier transform, a gain variable according to an excessive quantity relative to the reference value is used for each frame to control signal intensity such that the amplitude thereof is at most the reference value.

Communication equipment which receives OFDM signal, OFDM-based wireless communication system and method for receiving OFDM signal

A wireless communication which suppresses radio interference between wireless base stations and improves the channel efficiency is implemented. In the wireless communication system including a central base station, a plurality of remote base stations having a direction-variable antenna, and a plurality of mobile stations to communicate with the remote base stations, the central base station performs centralized management of radio-wave beam patterns to be sent to the plurality of mobile stations which will communicate with remote base stations and performs packet scheduling of the mobile stations in such a manner that radio waves sent from the remote base stations will not cause strong interference at the mobile stations.

Wireless communication system

A terminalmeasures pilot signals transmitted in directional (beam) patterns from an adjacent cell and an own cell, and estimates reception qualities with the presence (high)/absence (low) of the interference from the adjacent cell. The terminalrequests data rate request values (DRC, DRC) corresponding to the reception qualities with the presence/absence of the interference to the base station. The base stationshares beam direction schedule with an adjacent cell base station, and confirms the presence/absence of interference to the terminalfor each slot. In accordance with the presence/absence of the interference, the base stationselects a suitable one of the two values of the data rates requested from the terminal, and modulates the data and transmits it.

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Fujisawa, Japan

Koki Uwano