Abstract: A radio communication system (1) is provided with a high-power base station (200), a radio terminal (300) which is located within a macro cell (C2) formed by the high-power base station (200), and a low-power base station (100) which has a lower transmission output power than the high-power base station (200). The low-power base station (100) sends, to the high-power base station (200), control information needed for the radio communication between the radio terminal (300) and the low-power base station (100); the high-power base station (200) sends, to the radio terminal (300), the control information received from the low-power base station (100); and the radio terminal (300) performs radio communication with the low-power base station (100) by using the control information received from the high-power base station (200).

Abstract: Disclosed is a radio base station (100) provided with: a reception unit (111) that receives, from a radio terminal, a reference signal multiplexed with an ACK or a NACK; an ACK/NACK detection unit (121) that detects the ACK or NACK multiplexed onto the reference signal, using a detection criterion (1) set such that the ACK false-positive rate is lower than the NACK false-positive rate; an ACK/NACK detection unit (123) that detects the ACK or NACK multiplexed onto the reference signal, using a detection criterion (2) set such that the relationship between the ACK false-positive rate and the NACK false-positive rate is different from that in the detection criterion (1); a transmission/retransmission control unit (122) that controls retransmission of data in accordance with the detection result from the ACK/NACK detection unit (121); and a channel estimation unit (124) that performs channel estimation using the reference signal from which the ACK/NACK is removed in accordance with the detection result from the A

Abstract: A radio communication device according to the present invention adaptively controls directivity of a transmission radio signal by using a plurality of element antennas on the basis of a received radio signal received from a communication target counterpart radio communication device. The radio communication device includes a transmission controller configured to process the transmission radio signal according to a first control method for adaptively controlling the directivity, a propagation path state detector configured to detect fluctuation state of a propagation path to a counterpart radio communication device, and a judgment unit configured to judge whether or not to change the directivity on the basis of the fluctuation state of the propagation path. If it is judged that the directivity is to be changed, the transmission controller switches to a second control method that is different from the first control method, and processes the transmission radio signal according to the second control method.

Abstract: A radio communication device according to the present invention is a radio communication device which adaptively controls directivity of transmission radio signals by use of a plurality of element antennas on the basis of received radio signals received from a counterpart radio communication device that is a communication target radio communication device, the transmission radio signals being to be transmitted to the counterpart radio communication device, the radio communication device comprising: a propagation path state detector configured to detect a fluctuation state of a propagation path to the counterpart radio communication device on the basis of the received radio signal; and a transmission controller configured to control a phase of the transmission radio signal on the basis of the fluctuation state of the propagation path detected by the propagation path state detector.

Abstract: A channel estimation and prediction unit 18 estimates a channel and predicts a plurality of channels for a next transmission slot. An SVD unit 19 performs singular value decomposition on a plurality of channel prediction values. An eigenvalue calculation unit 20 calculates a plurality of eigenvalues in a slot, whereas an eigenmode quality calculation unit 21 calculates a single quality for each eigenmode, considering variation frequency of the eigenvalue in the slot and outputs the quality to a transmission adaptive control unit 22.

Abstract: A reception device 10 includes a channel estimator 130 configured to calculate channel estimation information for each of first to fourth known signals, the channel estimation information indicating estimation of a characteristic of a channel of the radio signal and an SNR estimator 150 configured to interpolate channel estimation information on an intersection by using the channel estimation information on each of the first known signal and the fourth known signal, the intersection being where a line joining the first known signal and the fourth known signal intersects with a line joining the second known signal and the third known signal, and to interpolate channel estimation information on the intersection by using the channel estimation information on each of the second known signal and the third known signal, and to calculate noise power of the radio signal on the basis of a difference between the interpolated two channel estimation information.

Abstract: Provided is a channel information prediction system which uses a low ray element in a transformation MIMO CSI to calculate a first prediction filter coefficient. By using the obtained first prediction filter coefficient, the system executes a first prediction for predicting channel information upon a radio signal transmission in the future and suppresses a component of the ray contained in the low ray element. By using the low ray component in which the ray component is suppressed, the system executes a second prediction for predicting channel information upon a radio signal transmission in the future.

Abstract: Provided is a channel information prediction system (10) which calculates a MIMO CSI prediction value as a predicted value of the MIMO CSI in the future by using the MIMO CSI and the transformation matrix indicating a transmission path characteristic between a transmitter (100) and a receiver (200) in an multi-antenna transmission system (1) using an antenna array formed by transmission antennas (#1 to #T) or reception antennas (#1 to #R) in the transmitter (100) and the receiver (200). The channel information prediction system (10) calculates the transformation matrix according to an array response or an array weight of the antenna array correlated with the arrival direction or the departure direction by using a direction estimation technique for estimating the arrival direction or the departure direction of the radio signal.

Abstract: A channel estimation and prediction unit 18 estimates a channel and predicts a channel for a next transmission slot. An SVD unit 19 performs singular value decomposition on each channel prediction value. An eigenvalue calculation unit 20 calculates an eigenvalue in a slot, whereas an eigenmode quality calculation unit 21 calculates quality of each eigenmode based on the eigenvalue obtained from the eigenvalue calculation unit 20 and outputs the quality to a transmission adaptive control unit 22. The transmission adaptive control unit 22 recognizes frequency of channel variation based on variation of quality of a lower eigenmode and the likes, and corrects quality of a higher eigenmode to be a smaller value according to the frequency of channel variation being larger with respect to a slot length.

Abstract: A channel estimation and prediction unit 18 estimates a channel and predicts a plurality of channels for a next transmission slot. An SVD unit 19 performs singular value decomposition on a plurality of channel prediction values. An eigenvalue calculation unit 20 calculates a plurality of eigenvalues in a slot, whereas an eigenmode quality calculation unit 21 calculates a single quality for each eigenmode, considering variation frequency of the eigenvalue in the slot and outputs the quality to a transmission adaptive control unit 22.

Abstract: A reception device 10 includes a channel estimator 130 configured to calculate channel estimation information for each of first to fourth known signals, the channel estimation information indicating estimation of a characteristic of a channel of the radio signal and an SNR estimator 150 configured to interpolate channel estimation information on an intersection by using the channel estimation information on each of the first known signal and the fourth known signal, the intersection being where a line joining the first known signal and the fourth known signal intersects with a line joining the second known signal and the third known signal, and to interpolate channel estimation information on the intersection by using the channel estimation information on each of the second known signal and the third known signal, and to calculate noise power of the radio signal on the basis of a difference between the interpolated two channel estimation information.

Abstract: A radio base station 1100 comprises a frequency-domain/time-domain converter 1160 for converting transfer route estimation information again into a time domain signal series or a signal series in a time domain, and a time domain SNR estimator 1170 for calculating the signal power of a radio signal on the basis of the time domain signal series contained in a time band (ts), of the whole time domain containing the time domain signal series converted again, and for calculating a noise power on the basis of the time domain signal series contained in a time band (tn), thereby to estimate the signal-to-noise ratio of the radio signal.

Abstract: When receiving a signal from the antenna #1 (initially receiving a signal from an omnidirectional antenna), a guard interval correlator 12 calculates correlation of a guard interval portion of the received signal and an output measuring unit 13 measures a peak output of the guard interval correlator 12. A comparator 14 compares the peak output measured by the output measuring unit 13 with a preset threshold, and when the peak output falls below the preset threshold and outputs an antenna switching control signal to an antenna switch 11, and the antenna switch 11 switches to the antenna #2 having a different directivity.

Abstract: A radio communication device according to the present invention adaptively controls directivity of a transmission radio signal by using a plurality of element antennas on the basis of a received radio signal received from a communication target counterpart radio communication device. The radio communication device includes a transmission controller configured to process the transmission radio signal according to a first control method for adaptively controlling the directivity, a propagation path state detector configured to detect fluctuation state of a propagation path to a counterpart radio communication device, and a judgment unit configured to judge whether or not to change the directivity on the basis of the fluctuation state of the propagation path. If it is judged that the directivity is to be changed, the transmission controller switches to a second control method that is different from the first control method, and processes the transmission radio signal according to the second control method.

Abstract: A radio communication device according to the present invention is a radio communication device which adaptively controls directivity of transmission radio signals by use of a plurality of element antennas on the basis of received radio signals received from a counterpart radio communication device that is a communication target radio communication device, the transmission radio signals being to be transmitted to the counterpart radio communication device, the radio communication device comprising: a propagation path state detector configured to detect a fluctuation state of a propagation path to the counterpart radio communication device on the basis of the received radio signal; and a transmission controller configured to control a phase of the transmission radio signal on the basis of the fluctuation state of the propagation path detected by the propagation path state detector.

Abstract: A radio base station includes: a propagation path characteristic acquisition unit which acquires propagation path characteristics between a radio communication terminal and a radio base station; and a channel controller which reports to the radio communication terminal that channel allocation information is transmitted by using a dedicated control channel if the acquired propagation characteristic satisfies a predetermined condition. After the channel control unit has reported to the radio communication terminal that the channel allocation information is transmitted by using an dedicated control channel, the channel control unit and a MAP processing unit transmit the channel allocation information by using an dedicated control channel instead of a broadcast control channel in the downstream frame.

Abstract: A radio base station 100 includes fading rate measurement units 103a to 103n configured to measure a fading rate of a radio signal for each of the antenna elements 101a to 101n, the radio signal being received through the antenna elements; and a reference signal calculator 105 configured to output a reference signal used in an adaptive control of the directivity of the array antenna 101. The reference signal calculator 105 outputs the reference signal on the basis of a plurality of fading rates measured by the fading rate measurement units 103a to 103n.

Abstract: Provided is a radio communication method employed in a base station having plural antenna elements. The method includes the steps of: setting an inner zone and an outer zone by dividing a cell formed by the base station into two; determining whether a mobile station is located in the inner zone or the outer zone on the basis of a predetermined criterion; notifying the mobile station located in the inner zone of control information, including information on channel allocation and a communication method, through a broadcast channel; and notifying the mobile station located in the outer zone of control information through a dedicated channel by beamforming using the plural antenna elements.

Abstract: A communication device according to the present invention includes a receiver configured to receive, through a radio link, packet signals each including a known signal indicating information known by the communication device and an unknown signal indicating information not known by the communication device, and a combiner configured to combine the packet signals while decreasing noise signals included in each of the packet signals. The communication device includes a correlation comparator configured to compare a correlation between the known signals in each of the packet signals with a correlation between the unknown signals in each of the packet signals, and a combining scheme controller configured to control a scheme of combining the packet signals, on the basis of the comparison result by the correlation comparator.

Abstract: An adaptive array antenna apparatus for performing adaptive control based on received signals received by a plurality of antenna elements which form an array antenna. The apparatus includes a computation part for computing an error of the received signals at different timings; an error comparison part for comparing the errors at the different timings with each other; and a weighting synthesizing part for performing weighting synthesis based on results of the comparison. Based on the results of the comparison, the computation part releases at least a part of computation resources required for the computation of the errors, and terminates the computation of the errors. Typically, the computation part performs the release of the computation resources when it is determined that the error has a minimum value, and terminates the computation of the errors.