Importance

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Abstract

A method and apparatus in a wireless communication system comprising at least one transmitter provided with at least two antennas and at least one receiving unit provided with at least one antenna and wherein training sequences are transmitted from the at least two antennas of the at least one transmitter to the at least one antenna of the at least one receiving unit. Characterized in that first, prior to the transmission, a training sequence P(k) is Inverse Discrete Fourier Transformed to a sequence p(n). Second, for each antenna branch the Inverse Discrete Fourier Transformed sequence p(n) is cyclically rotated by a predetermined step, said predetermined step being p(n) is cyclically rotated by a predetermined step, said predetermined step being different for each antenna branch to generate cyclically rotated training sequences p(n-n1), p(n-n2). Third, the cyclically rotated training sequences p(n-n1), p(n-n2) are transmitted concurrently from said at least two antennas to the receiving unit. Fourth, at the receiving unit receiving the cyclically rotated training sequences, the received sequences being a superposition of transmitted training sequences, each individually affected by the propagation medium, are used to provide channel impulse response estimates for the transmission from respective antenna.

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First Claim