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US 6,327,310 B1Granted
Wireless transmission method for antenna arrays, having improved resistance to fading
AssigneeLucent Technologies Inc.
InventorsBertrand M. Hochwald, Thomas Louis Marzetta
Life of this patent
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Abstract
Disclosed is a modulation method for wireless signal transmission. Each message that is transmitted is made up of a sequence of signals, each selected from a constellation of L such signals, L a positive integer. Each transmitted signal is distributed spatially across a transmitting antenna array, and is also distributed in time. Thus, each signal may be represented as a T×M matrix, in which each of the M columns represents a distinct antenna of the array, and each of the T rows represents a distinct time interval. Each entry in this matrix represents a complex baseband voltage amplitude. Each of these signal matrices is proportional to a matrix having orthonormal columns.
Claims18
A method of wireless communication, comprising:
- generating at least one baseband signal;
- and transmitting said signal, on a radiofrequency carrier, from an array of two or more transmission antennas, wherein:
- a) each said baseband signal is selected from a plurality of symbols, to be referred to as a constellation;
- b) each said baseband signal consists of a plurality of amplitudes to be distributed across the antenna array and to be distributed in discrete time;
- c) each symbol is equivalent to a matrix in which each column represents a distinct antenna of the array, and each row represents a distinct time interval;
- and
- d) the constellation is equivalent to a set of matrices in each of which all columns are orthonormal.
4 more elements
A method of wireless communication, comprising:
- generating at least one baseband signal;
- and transmitting said signal, on a radiofrequency carrier, from an array of one or more transmission antennas, wherein:
- a) each said baseband signal is selected from a plurality of symbols, to be referred to as a constellation;
- b) each said baseband signal consists of a plurality of amplitudes to be distributed across the antenna array and to be distributed in discrete time;
- c) each symbol is equivalent to a matrix in which each column represents a distinct antenna of the array, and each row represents a distinct time interval;
- d) any two matrices Φ1, Φ2 corresponding to respective signals of the signal constellation have a matrix product Φ1*Φ2, wherein the symbol * denotes conjugate transposition;
- e) for all pairs of matrices in the constellation, every said matrix product has a set of one or more singular values;
- and
- f) the signals of the signal constellation are chosen in a manner that tends to collectively minimize the singular values.
6 more elements
A method of wireless communication, comprising:
- generating at least one baseband signal;
- and transmitting said signal, on a radiofrequency carrier, from an array of one or more transmission antennas, wherein:
- a) each said baseband signal is selected from a plurality of symbols, to be referred to as a constellation;
- b) each said baseband signal consists of a plurality of amplitudes to be distributed across the antenna array and to be distributed in discrete time;
- c) each symbol is equivalent to a matrix in which each column represents a distinct antenna of the array, and each row represents a distinct time interval;
- d) any two matrices Φ1, Φ2 corresponding to respective signals of the signal constellation have a matrix product Φ1*Φ2, wherein the symbol * denotes conjugate transposition;
- e) for all pairs of matrices in the constellation, every said matrix product has a set of one or more singular values;
- f) the constellation is equivalent to a set of matrices normalized such that all columns have unit magnitude;
- and
- g) under said normalization, the singular values are all less than 0.8.
7 more elements
A method of wireless communication, comprising:
- receiving, at one or more receiving antennas, at least one radiofrequency signal from an array of two or more transmission antennas;
- demodulating the received signal to obtain therefrom a baseband signal;
- and subjecting the baseband signal to a decision process, thereby to recover a transmitted signal from the baseband signal, wherein:
- a) the decision process comprises computing a score for each of a plurality of candidate symbols, said plurality to be referred to as a constellation, and identifying, as the transmitted signal, that candidate signal which yields the best score;
- b) each candidate signal consists of a plurality of amplitudes to be distributed across the transmission antenna array and to be distributed in discrete time;
- c) each candidate signal is equivalent to a matrix in which each column represents a distinct antenna of the transmission array, and each row represents a distinct time interval;
- and
- d) the constellation is equivalent to a set of matrices in each of which all columns are orthonormal.
5 more elements
A method of wireless communication, comprising:
- receiving, at one or more receiving antennas, at least one radiofrequency signal from an array of one or more transmission antennas;
- demodulating the received signal to obtain therefrom a baseband signal;
- and subjecting the baseband signal to a decision process, thereby to recover a transmitted signal from the baseband signal, wherein:
- a) the decision process comprises computing a score for each of a plurality of candidate symbols, said plurality to be referred to as a constellation, and identifying, as the transmitted signal, that candidate signal which yields the best score;
- b) each candidate signal consists of a plurality of amplitudes to be distributed across the transmission antenna array and to be distributed in discrete time;
- c) each candidate signal is equivalent to a matrix in which each column represents a distinct antenna of the transmission array, and each row represents a distinct time interval;
- d) any two matrices Φ1,Φ2 corresponding to respective signals of the signal constellation have a matrix product Φ1*Φ2, wherein the symbol * denotes conjugate transposition;
- e) for all pairs of matrices in the constellation, every said matrix product has a set of one or more singular values;
- and
- f) the signals of the signal constellation are chosen in a manner that tends to collectively minimize the singular values.
7 more elements
A method of wireless communication, comprising:
- receiving, at one or more receiving antennas, at least one radiofrequency signal from an array of one or more transmission antennas;
- demodulating the received signal to obtain therefrom a baseband signal;
- and subjecting the baseband signal to a decision process, thereby to recover a transmitted signal from the baseband signal, wherein:
- a) the decision process comprises computing a score for each of a plurality of candidate symbols, said plurality to be referred to as a constellation, and identifying, as the transmitted signal, that candidate signal which yields the best score;
- b) each candidate signal consists of a plurality of amplitudes to be distributed across the transmission antenna array and to be distributed in discrete time;
- c) each candidate signal is equivalent to a matrix in which each column represents a distinct antenna of the transmission array, and each row represents a distinct time interval;
- d) any two matrices Φ1, Φ2 corresponding to respective signals of the signal constellation have a matrix product Φ1* Φ2, wherein the symbol * denotes conjugate transposition;
- e) for all pairs of matrices in the constellation, every said matrix product has a set of one or more singular values;
- f) the constellation is equivalent to a set of matrices normalized such that all columns have unit magnitude;
- and
- g) under said normalization, the singular values are all less than 0.8.
8 more elements
Dependencies are inferred from the claim text.