Generalized m-rank beamformers for MIMO systems using successive quantization
First Claim
1. A method for use in communication systems for transmitting signals from a transmitter having t transmit antennas and a receiver having r receive antennas by forming beams of electromagnetic radiation used to transmit signals from the transmitter to the receiver, the method comprising:
- transmitting a test signal from the transmitter to the receiver;
computing a channel matrix by observing the effect of transmission on the test signal;
selecting at least one eigenvector of the channel matrix, to achieve a desired performance level;
selecting a beamforming vector from at least one codebook of predetermined beamforming vectors wherein the selected beamforming vector best approximates the at least one eigenvector;
transmitting information identifying the selected beamforming vector from the receiver to the transmitter; and
using the selected beamforming vector to transmit a signal from the transmitter to the receiver so that the desired performance level is achieved.
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Accused Products
Abstract
The telecommunications system described herein implements a multi-rank beamformer for use in wireless systems equipped with multiple transmit and multiple receive antennas. The multi-rank beamformer uses finite-rate feedback of channel conditions to achieves close to theoretical performance indicated by the water-filling algorithm, while avoiding the computational complexity associated with space time codes. In addition, the multi-rank beamforming system described herein improves on the performance of unit rank beamforming methods by maintaining the gains over space time codes over a broader range of transmission rates.
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Citations
16 Claims
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1. A method for use in communication systems for transmitting signals from a transmitter having t transmit antennas and a receiver having r receive antennas by forming beams of electromagnetic radiation used to transmit signals from the transmitter to the receiver, the method comprising:
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transmitting a test signal from the transmitter to the receiver; computing a channel matrix by observing the effect of transmission on the test signal; selecting at least one eigenvector of the channel matrix, to achieve a desired performance level; selecting a beamforming vector from at least one codebook of predetermined beamforming vectors wherein the selected beamforming vector best approximates the at least one eigenvector; transmitting information identifying the selected beamforming vector from the receiver to the transmitter; and using the selected beamforming vector to transmit a signal from the transmitter to the receiver so that the desired performance level is achieved. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for use in communication systems comprising a transmitter having t transmit antennas and a receiver having r receive antennas, wherein transmission occurs over a channel mathematically represented by channel matrix H, and wherein signal transmission between the transmitter and receiver occurs according to an approximation of the waterfilling algorithm accomplished by selecting predetermined beamforming codebooks for modifying signals to be transmitted from the transmitter to the receiver, the method comprising:
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specifying a desired performance level specification for characterizing the performance of the communications system over a range of operating conditions; jointly determining a feedback budget and beamforming codebook specification that achieves the performance criteria set forth in the performance level specification, wherein the feedback budget refers, at least in part, to the transmission of bits from the receiver to the transmitter identifying vectors contained in the beamforming codebook specification, wherein the codebook vectors are used to modify signals transmitted by the transmitter to the receiver. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A beamforming system for use in a telecommunications system comprising at least one base station having t transmit antennas and at least one mobile station having r receive antennas, the beamforming system for use in beamforming of signals transmitted from the base station to the mobile station, the beamforming system comprising:
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in the base station; a test signal generator and transmitter for generating test signals to be transmitted from the base station to the mobile station; at least one beamforming codebook comprising predetermined beamforming vectors for beamforming of signals transmitted by the base station to the mobile station; a feedback receiver for receiving codes from the mobile station identifying which beamforming vectors available in the at least one beamforming codebook should be used in beamforming of signals transmitted by the base station to the mobile station; and a beamformer for using the beamforming vectors selected by the mobile station to beamform signals transmitted from the base station to the mobile station; in the mobile station; a test signal receiver for receiving the test signal transmitted by the test signal generator and transmitter of the base station; a channel matrix calculator for calculating at least the principal eigenvector of a channel matrix describing the state of the transmission channel between the base station and the mobile station by observing the effect of the channel on the test signal; at least one beamforming codebook comprising predetermined beamforming vectors for beamforming of signals transmitted from the base station to the mobile station, wherein the beamforming vectors comprising the beamforming codebook are identical to those comprising the at least one beamforming codebook located in the base station; a beamforming vector selector for selecting which beamforming vector in the at least one beamforming codebook best approximates the principal eigenvector of the channel matrix; a beamforming vector code selector for selecting the unique predetermined code which identifies the beamforming vector which best approximates the principal eigenvector of the channel matrix; a beamforming vector code transmitter for transmitting the code identifying the beamforming vector which best approximates the principal eigenvector of the channel matrix to the feedback receiver of the base station.
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15. A base station having t transmit antennas for use in a telecommunications system comprising the base station and mobile stations having r receive antennas, the base station comprising:
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test signal generator and transmitter for generating test signals to be transmitted from the base station to a mobile station; at least one beamforming codebook comprising predetermined beamforming vectors for beamforming of signals transmitted by the base station to the mobile station; a feedback receiver for receiving codes from the mobile station identifying which beamforming vectors available in the at least one beamforming codebook should be used in beamforming of signals transmitted by the base station to the mobile station; and a beamformer for using the beamforming vectors selected by the mobile station to beamform signals transmitted from the base station to the mobile station.
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16. A mobile station having r receive antennas for use in a telecommunications system comprising the mobile station and base stations having t transmit antennas, the mobile station comprising:
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a test signal receiver for receiving a test signal transmitted by a base station; a channel matrix calculator for calculating at least the principal eigenvector of a channel matrix describing the state of the transmission channel between the base station and the mobile station by observing the effect of the channel on the test signal; at least one beamforming codebook comprising predetermined beamforming vectors for beamforming of signals transmitted from the base station to the mobile station, wherein the beamforming vectors comprising the beamforming codebook are identical to those comprising the at least one beamforming codebook located in the base station; a beamforming vector selector for selecting which beamforming vector in the at least one beamforming codebook best approximates the principal eigenvector of the channel matrix; a beamforming vector code selector for selecting the unique predetermined code which identifies the beamforming vector which best approximates the principal eigenvector of the channel matrix; and a beamforming vector code transmitter for transmitting the code identifying the beamforming vector which best approximates the principal eigenvector of the channel matrix to a base station.
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Specification