Wireless communications system, wireless communications method, and wireless communications apparatus
First Claim
1. A wireless communications system for a communication between a transmitter and a receiver each having a plurality of antennas, over a communications channel by multiplexing a signal, the system comprising:
- a reference signal sender which feeds back reference signals for respective antennas of the receiver from the receiver to the transmitter;
a first channel information acquirer which calculates, based on the reference signals received by the transmitter, a channel information matrix H whose elements represent transfer functions of respective communication sub-channels of the channel each of which links one of the antennas of the transmitter and one of the antennas of the receiver;
an SVD unit which performs a singular value decomposition of the channel information matrix H to yield UDVH, so as to obtain a transmit antenna weighting coefficient matrix V whose entries represent weighting vectors for the respective antennas of the transmitter; and
a signal sender which sends the components of a reference signal from the respective antennas of the transmitter to the receiver with the components weighted by the transmit antenna weighting coefficient matrix V;
a second channel information acquirer which calculates, based on the weighted reference signals received by the receiver, a channel information matrix H′
corresponding to the transmit antenna weighting coefficient matrix V and respective antennas of the receiver;
a receive antenna weighting coefficient matrix decision unit, in the receiver, configured to determine a receive antenna weighting coefficient matrix based on the channel information matrix H′
; and
a decoder, in the receiver, configured to decode a received signal, which is received after obtaining the receive antenna weighting coefficient matrix based on the received antenna weighting coefficient matrix.
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Accused Products
Abstract
In an SVD-MIMO transmission using a singular value decomposition, the amount of information fed back to a transmitter from a receiver is reduced. Instead of feeding back to the transmitter, a transmission weighting vector V obtained by performing a singular value decomposition of a channel information matrix obtained by the receiver, the receiver sends reference symbols to the transmitter, which obtains the channel information matrix and performs the singular value decomposition to yield the vector V necessary when transmitting data. In the procedure of obtaining the vector V, a noncoincidence between channel matrices in the opposite directions is compensated for, by performing a calibration for compensating an error between transmitting and receiving analog devices on the part of both the transmitter and the receiver.
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Citations
8 Claims
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1. A wireless communications system for a communication between a transmitter and a receiver each having a plurality of antennas, over a communications channel by multiplexing a signal, the system comprising:
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a reference signal sender which feeds back reference signals for respective antennas of the receiver from the receiver to the transmitter; a first channel information acquirer which calculates, based on the reference signals received by the transmitter, a channel information matrix H whose elements represent transfer functions of respective communication sub-channels of the channel each of which links one of the antennas of the transmitter and one of the antennas of the receiver; an SVD unit which performs a singular value decomposition of the channel information matrix H to yield UDVH, so as to obtain a transmit antenna weighting coefficient matrix V whose entries represent weighting vectors for the respective antennas of the transmitter; and a signal sender which sends the components of a reference signal from the respective antennas of the transmitter to the receiver with the components weighted by the transmit antenna weighting coefficient matrix V; a second channel information acquirer which calculates, based on the weighted reference signals received by the receiver, a channel information matrix H′
corresponding to the transmit antenna weighting coefficient matrix V and respective antennas of the receiver;a receive antenna weighting coefficient matrix decision unit, in the receiver, configured to determine a receive antenna weighting coefficient matrix based on the channel information matrix H′
; anda decoder, in the receiver, configured to decode a received signal, which is received after obtaining the receive antenna weighting coefficient matrix based on the received antenna weighting coefficient matrix.
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2. A wireless communications system taking account of a transfer function of a communications channel between a transmitter and a receiver each having an antenna, the system comprising:
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a calibration coefficient obtainer which obtains a calibration coefficient for each of the antennas of the transmitter and the receiver by calculating a ratio of a transfer function of each of a transmission circuit and a reception circuit corresponding to each of the antennas; a reference signal feedback unit which feeds back a reference signal as compensated on the part of the receiver by using the calibration coefficient for the antenna of the receiver, to the transmitter; a transfer function calculator which compensates, on the part of the transmitter, the received calibrated reference signal by using the calibration coefficient for the antenna of the transmitter, and obtains a transfer function based on the compensated reference signal; and a data sender which transmits data using the transfer function. - View Dependent Claims (3, 4)
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5. A wireless communications method for a communication between a transmitter and a receiver each having a plurality of antennas, over a communications channel by multiplexing a signal, the method comprising:
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feeding back reference signals for respective antennas of the receiver from the receiver to the transmitter; calculating, based on the reference signals received by the transmitter, a channel information matrix H whose elements represent transfer functions of respective communication sub-channels of the channel each of which links one of the antennas of the transmitter and one of the antennas of the receiver; performing a singular value decomposition of the channel information matrix H to yield UDVH, so as to obtain a transmit antenna weighting coefficient matrix V whose entries represent weighting vectors for the respective antennas of the transmitter; sending the components of a reference signal from the respective antennas of the transmitter to the receiver with the components weighted by the transmit antenna weighting coefficient matrix V; calculating, based on the weighted reference signals received by the receiver, a channel information matrix H′
corresponding to the transmit antenna weighting coefficient matrix and respective antennas of the receiver;determining a receive antenna weighting coefficient matrix based on the channel information matrix H′
; anddecoding a signal received after obtaining the receive antenna weighting coefficient matrix based on the received antenna weighting coefficient matrix.
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6. A wireless communications method taking account of a transfer function of a communications channel between a transmitter and a receiver each having an antenna, the method comprising steps of:
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obtaining a calibration coefficient for each of the antennas of the transmitter and the receiver by calculating a ratio of a transfer function of each of a transmission circuit and a reception circuit corresponding to each of the antennas; feeding back a reference signal as compensated on the part of the receiver by using the calibration coefficient for the antenna of the receiver, to the transmitter; compensating, on the part of the transmitter, the received calibrated reference signal by using the calibration coefficient for the antenna of the transmitter, and obtaining a transfer function based on the compensated reference signal; and sending data using the transfer function. - View Dependent Claims (7, 8)
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Specification