Abstract: The number of OFDM symbols for channel estimation is reduced, overhead due to a pilot signal and a feedback signal is reduced, and the throughput is improved.

Abstract: Interference in preamble signals and pilot signals in cooperative transmission using interference suppressing technology is avoided. A wireless apparatus for transmitting a wireless signal on which directivity control has been performed to stations in a wireless system including at least one wireless apparatus is provided with a known signal generating unit which generates a known signal to be added to the wireless signal, a weighting processing unit which performs weighting on the known signal generated by the known signal generating unit, and a wireless processing unit which transmits the known signal on which the weighting has been performed by the weighting processing unit.

Abstract: Provided is a wireless communication system employing network coding which can set transmission quality for each destination of packets and improve throughput. The wireless communication system is provided with a wireless relay station apparatus and wireless terminal station apparatuses. The wireless relay station apparatus selects coding rates to be used for a first packet and a second packet in accordance with communication quality required for the first packet and the second packet, generates error correction encoded packets having the same data length from the first packet and the second packet using the selected coding rates, performs network encoding on the error correction encoded first and second packets to generate a network encoded packet, and transmits the generated network encoded packet.

Abstract: Provided are a wireless communication method, a base station, a wireless communication system and a communication apparatus whereby an interference power is calculated from an estimated propagation channel estimation result and the transmission power is controlled based on the interference power or the interference is suppressed by controlling the directivity, thereby increasing the transmission capacity. A propagation channel estimation circuit performs propagation channel estimation from a response signal transmitted from a terminal station and estimates a propagation channel estimation result. An interference power calculation circuit measures each interference power from a signal of each sub-carrier received by each of wireless units, and calculates an interference power for each sub-carrier from the propagation channel estimation result estimated by the propagation channel estimation circuit.

Abstract: A spatial multiplexing wireless transmission system is formed by a base station, and by a plurality of terminal stations that are provided with a plurality of antennas. The base station is provided with an information signal generating portion, a control signal generating portion, a transmission frame generating portion, a multiple beamforming portion, a transmission/reception switching portion, a reception signal processing portion, a propagation environment estimating portion, and an antenna information generating portion. At least one of the terminal stations is provided with a transmission/reception switching portion, a reception signal processing portion, a decoding portion, an antenna information extracting portion, an antenna information generating portion, an transmitting portion, a battery, a remaining battery detecting portion, a transmission request extracting portion, and a propagation environment estimating portion.

Abstract: An actuator includes a stepping motor; a multi-stage gear device including a first stage gear attached to a rotation shaft of the motor, wherein a gear of each stage engages with a gear of a next stage; and a base member on which the multi-stage gear device and the stepping motor are mounted, wherein in the multi-stage gear device, a grease composition for resin is applied to a bearing part of the gear, and to an engaging part between the gears, and the grease composition for resin includes: (a) a base oil including a poly-alpha-olefin oil with a kinematic viscosity at 100° C. of 4 to 6 mm2/s; (b) a thickening agent which is lithium soap; (c) a viscosity increasing agent; (d) a solid lubricant; and (e) an anti-wear agent, and wherein the NLGI consistency number of the composition is 00, 0, 1, or 2.

Abstract: The number of training signals for channel estimation is reduced.

Abstract: In a system which performs wireless communication from an access point to stations using group identification information, the frequency of uses of group identification information that overlaps with that of another access point is reduced. An association between a station apparatus included in a group that is a target for simultaneous transmission and group identification information is stored, each station apparatus included in the group is notified of the group identification information, group identification information that is being used in the other access point apparatus is acquired, and if group identification information that is being used by the access point apparatus itself overlaps with the group identification information used by the other access point apparatus, the group identification information is changed so as to reduce the number of pieces of overlapping group identification information.

Abstract: Communication quality is prevented from being deteriorated due to interference caused by low accuracy of channel information or interference from another base station or another wireless communication system. A wireless communication system includes a first wireless station including a plurality of antenna elements, transmission units corresponding to the plurality of antenna elements, and a transmission directivity control unit that controls transmission directivity of the plurality of antenna elements, and a plurality of second wireless stations each including a reception power measurement unit that measures a reception power. The transmission directivity control unit determines the transmission directivity of each of the plurality of antenna elements so that a signal does not reach a particular second wireless station among the plurality of second wireless stations. The transmission units generate wireless signals using the transmission directivity.

Abstract: Provided are a wireless communication method, a base station, a wireless communication system and a communication apparatus whereby an interference power is calculated from an estimated propagation channel estimation result and the transmission power is controlled based on the interference power or the interference is suppressed by controlling the directivity, thereby increasing the transmission capacity. A propagation channel estimation circuit performs propagation channel estimation from a response signal transmitted from a terminal station and estimates a propagation channel estimation result. An interference power calculation circuit measures each interference power from a signal of each sub-carrier received by each of wireless units, and calculates an interference power for each sub-carrier from the propagation channel estimation result estimated by the propagation channel estimation circuit.

Abstract: An interference cancelling station ICS includes a transmission weight factor calculating unit calculating a transmission weight factor w2 and an interference cancelling data signal transmitting unit generating an interference cancelling data signal by multiplying, by the transmission weight factor w2, a data signal transmitted by a base station BSb of the wireless communication system B and transmitting the interference cancelling data signal in synchronization with timing with which the base station BSb of a wireless communication system B transmits the data signal, and a mobile station MSa of a wireless communication system A receives a data signal transmitted by a base station BSa of the wireless communication system A, the data signal having cancelled interference from the base station BSb of the wireless communication system B.

Abstract: A spatial multiplexing wireless transmission system is formed by a base station, and by a plurality of terminal stations that are provided with a plurality of antennas. The base station is provided with an information signal generating portion, a control signal generating portion, a transmission frame generating portion, a multiple beamforming portion, a transmission/reception switching portion, a reception signal processing portion, a propagation environment estimating portion, and an antenna information generating portion. At least one of the terminal stations is provided with a transmission/reception switching portion, a reception signal processing portion, a decoding portion, an antenna information extracting portion, an antenna information generating portion, an transmitting portion, a battery, a remaining battery detecting portion, a transmission request extracting portion, and a propagation environment estimating portion.

Abstract: Provided is a wireless communication system employing network coding which can set transmission quality for each destination of packets and improve throughput. The wireless communication system is provided with a wireless relay station apparatus and wireless terminal station apparatuses. The wireless relay station apparatus selects coding rates to be used for a first packet and a second packet in accordance with communication quality required for the first packet and the second packet, generates error correction encoded packets having the same data length from the first packet and the second packet using the selected coding rates, performs network encoding on the error correction encoded first and second packets to generate a network encoded packet, and transmits the generated network encoded packet.

Abstract: An interference cancelling station ICS includes a transmission weight factor calculating unit calculating a transmission weight factor w2 and an interference cancelling data signal transmitting unit generating an interference cancelling data signal by multiplying, by the transmission weight factor w2, a data signal transmitted by a base station BSb of the wireless communication system B and transmitting the interference cancelling data signal in synchronization with timing with which the base station BSb of a wireless communication system B transmits the data signal, and a mobile station MSa of a wireless communication system A receives a data signal transmitted by a base station BSa of the wireless communication system A, the data signal having cancelled interference from the base station BSb of the wireless communication system B.

Abstract: When OFDM signals are transmitted from a plurality of antennas, a pilot carrier is transmitted from one antenna among the plurality of antennas, and a null signal is transmitted from an antenna other than that antenna by a subcarrier of the frequency band that transmits the pilot carrier.

Abstract: An OFDM signal communication system used in broadband mobile communication, achieves stable operation under severe frequency selective fading environments, giving high quality. The OFDM signal communication system which transmits OFDM signals over the same radio frequency from N transmitting antennas, has an inverse matrix computer for computing an N×N inverse matrix constituted by propagation coefficients for respective propagation paths between each of N transmitting antennas and each of N receiving antennas, and a subcarrier demodulator which separates the signals of the respective propagation paths, based on the obtained inverse matrix.

Abstract: When OFDM signals are transmitted from a plurality of antennas, a pilot carrier is transmitted from one antenna among the plurality of antennas, and a null signal is transmitted from an antenna other than that antenna by a subcarrier of the frequency band that transmits the pilot carrier.

Abstract: An OFDM signal communication system used in broadband mobile communication, achieves stable operation under severe frequency selective fading environments, giving high quality. The OFDM signal communication system which transmits OFDM signals over the same radio frequency from N transmitting antennas, has an inverse matrix computer for computing an N×N inverse matrix constituted by propagation coefficients for respective propagation paths between each of N transmitting antennas and each of N receiving antennas, and a subcarrier demodulator which separates the signals of the respective propagation paths, based on the obtained inverse matrix.