Determining channel characteristics in a wireless communication system that uses multi-element antenna
First Claim
1. A method for use in a system that is adapted to transmit a data burst over at least two antennas, the method comprising the step of:
- transmitting at least two training sequences, each of the at least two training sequences being transmitted via a different respective one of said antennas, each of the at least two training sequences having a normalized auto-correlation below an auto-correlation threshold, the auto-correlation threshold being significantly less than unity, and each pair of the at least two training sequences having a normalized cross-correlation below a cross-correlation threshold, the cross-correlation threshold being significantly less than unity.
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Abstract
A method and apparatus for increasing in the data rate of a multiple-input and/or multiple-output system that has frequency selective fading by using training sequences with both low normalized auto-correlation and low normalized cross-correlation. Both 1) the sum of the square of the normalized auto-correlation of each training sequence over an auto-correlation window and 2) the sum of the square of the normalized cross-correlation of each pair of the training sequences over a cross-correlation window, are significantly less than unity. In one embodiment of the invention the training sequences are shifted versions of each other, and the low normalized cyclic-auto-correlation of cyclic sequences is significantly less than unity, with each cyclic sequence being N′, N′=N−L+1, symbols of one of the at least two training sequences. In another embodiment, the training sequences are ones where the trace of the inverse of the product of the matrix of training sequences'"'"' symbols and the conjugate transpose of this matrix is low. The matrix is a function of the number of symbols over which multipaths of significant power can arrive, the number of training sequences, and the number of symbols in a training sequence. More particularly the matrix is a block-toeplitzmatrix composed of the training symbols.
31 Citations
34 Claims
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1. A method for use in a system that is adapted to transmit a data burst over at least two antennas, the method comprising the step of:
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transmitting at least two training sequences, each of the at least two training sequences being transmitted via a different respective one of said antennas, each of the at least two training sequences having a normalized auto-correlation below an auto-correlation threshold, the auto-correlation threshold being significantly less than unity, and each pair of the at least two training sequences having a normalized cross-correlation below a cross-correlation threshold, the cross-correlation threshold being significantly less than unity. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for use in a system that is adapted to transmit a data burst over at least two antennas, the method comprising the step of:
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transmitting at least two training sequences, each of the at least two training sequences being transmitted via a different respective one of said antennas, the training sequences being shifted versions of each other, with each cyclic sequence having a normalized cyclic-auto-correlation below a cyclic-auto-correlation threshold, each cyclic sequence being N′
, N′
=N−
L+1, symbols of one of the at least two training sequences, the cyclic-auto-correlation threshold being significantly less than unity, L being the number of symbols over which multipaths of significant power can arrive, and N being the number of symbols in one of the training sequences. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A method for use in a system that is adapted to transmit a data burst over at least two antennas, the method comprising the step of:
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transmitting at least two training sequences, each of the at least two training sequences being transmitted via a different respective one of said antennas, a trace of an inverse of a product of a matrix of symbols of the at least two training sequences and a conjugate transpose of the matrix is below a trace threshold, the trace threshold being below 5 ML/(N−
L+1), L being the number of symbols over which multipaths of significant power can arrive, M being the number of training sequences, and N being the number of symbols in one of the training sequences. - View Dependent Claims (20, 21, 22, 23, 24, 25)
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26. A transmitter adapted to be coupled to at least two antennas,
the transmitter being further adapted to transmit at least two training sequences, each of the at least two training sequences being transmitted via a different respective one of said antennas, each of the at least two training sequences having a normalized auto-correlation below an auto-correlation threshold, the auto-correlation threshold being significantly less than unity, and each pair of the at least two training sequences having a normalized cross-correlation below a cross-correlation threshold, the cross-correlation threshold being significantly less than unity.
Specification