Method for calibrating a smart-antenna array radio transceiver unit and calibrating system

Claim 3

The method of claim 1 , wherein the transmitted and received signals are evaluated by determining the phase differences between the received signals and the respective transmitted signals, the determined phase differences being used for determining a value for a phase calibration for each of the at least two antenna elements.

Claim 4

The method of claim 2 , wherein for calibrating the antenna array a calibration phase for one of N at least two antenna elements is fixed to a value {circumflex over (B)} 1 and wherein the phases of N−1 further antenna elements are adjusted with calibration phases {circumflex over (B)} 2 to {circumflex over (B)} N , comprising: evaluating transmitted and received signals by determining their phase differences Δ ij , the first index indicating the respective transmitting and the second index indicating the respective receiving antenna element, both indices i,j lying between 1 and N; determining the calibration phases {circumflex over (B)} 2 to {circumflex over (B)} N based on suitable equations {circumflex over (B)} j −{circumflex over (B)} i ={circumflex over (x)} i −{circumflex over (x)} j −(ŷ i −ŷ j ), the hat {circumflex over ( )} denoting the phase of the respective variable, wherein x i is the transfer function of the transmit branch of the i th antenna element and wherein y j is the transfer function of the receive branch of the j th antenna element, and based on suitably determined phase differences Δ ij , the phase differences Δ ij corresponding to {circumflex over (x)} i +ŷ j and the indices i,j lying between 1 and N.

Claim 5

The method of claim 1 , wherein the transmitted and received signals are evaluated by determining the gain between received signals and the corresponding transmitted signals, the determined gains being used for determining a value for a amplitude calibration for each of the at least two antenna elements.

Claim 6

The method of claim 4 , comprising for an amplitude calibration of a smart antenna array with N at least two antenna elements: evaluating transmitted and received signals by determining the gain Δ ij a of the respective received signal compared to the respective transmitted signal, the first index indicating the respective transmitting and the second index indicating the respective receiving antenna element, both indices i,j lying between 1 and N; determining factors |B n |, with n=1 to N, for an amplitude correction for each of said N antenna elements based on the determined gains Δ ij a and based on the equations:  B n  =  x 1     y n   x n     y 1  , wherein x n is the transfer function of the transmit branch of the n th antenna element and wherein y n is the transfer function of the receive branch of the n th antenna element, the determined gains Δ ij a corresponding to |x i ∥y j |.

Claim 7

The method of claim 1 , wherein for a calibration of the smart antenna array for nulling operations, a factor for an amplitude correction is determined for each of the at least two antenna elements by evaluating signals transmitted between the transmit branch of one antenna element and the receive branch of another antenna element respectively.

Claim 8

A radio transceiver unit for a wireless access system using time division duplex comprising: a smart antenna array with at least two antenna elements, each including a transmit and a receive branch; a coupler in the transmit and the receive branch of each antenna element for coupling signals out of the transmit branches and for coupling signals into the receive branches; a physical connection between the coupler in the transmit branch of each antenna element and the coupler in the receive branch of at least one other antenna element respectively; selection means for selecting in a predetermined order at least each of those transmit branches of antenna elements connected to a receive branch of an antenna element that is connected at the same time to a transmit branch of at least one other antenna element to be employed for transmitting broadcast messages in predetermined broadcast periods during which the respective other antenna elements are prevented from transmitting signals; and processing means for evaluating signals transmitted via said connections for obtaining calibration information to be used for calibrating the smart antenna array.

Claim 9

A radio transceiver unit for a wireless access system using time division duplex comprising: a smart antenna array with at least two antenna elements, each including a transmit and a receive branch; a coupler in the transmit and the receive branch of each antenna element for coupling signals out of the transmit branches and for coupling signals into the receive branches; a physical connection between the coupler in the transmit branch of each antenna element and the coupler in the receive branch of at least one other antenna element respectively; selection means for selecting in a predetermined order at least each of those transmit branches of antenna elements connected to a receive branch of an antenna element that is connected at the same time to a transmit branch of at least one other antenna element to be employed for transmitting broadcast messages in predetermined broadcast periods during which the respective other antenna elements are prevented from transmitting signals; and processing means for evaluating signals transmitted via said connections for obtaining calibration information to be used for calibrating the smart antenna array.

Claim 10

The radio transceiver unit of claim 7 , wherein the processing means are designed for fixing a calibration phase for one of N at least two antenna elements to a value {circumflex over (B)} 1 ; evaluating transmitted and received signals by determining their phase differences Δ ij , the first index indicating the respective transmitting and the second index indicating the respective receiving antenna element, both indices i,j lying between 1 and N; and for determining the calibration phases {circumflex over (B)} 2 to {circumflex over (B)} N for the N−1 further antenna elements based on suitable equations {circumflex over (B)} j −{circumflex over (B)} i ={circumflex over (x)} i −{circumflex over (x)} j −(ŷ i −ŷ j ), the hat {circumflex over ( )} denoting the phase of the respective variable, wherein x i is the transfer function of the transmit branch of the i th antenna element and wherein y j is the transfer function of the receive branch of the j th antenna element, and based on suitably determined phase differences Δ ij , the phase differences Δ ij corresponding to {circumflex over (x)} i +ŷ j and the indices i,j lying between 1 and N.

Claim 11

The radio transceiver unit of claim 7 , wherein the processing means are designed for evaluating transmitted and received signals by determining the gain Δ ij a of the respective received signal compared to the respective transmitted signal, the first index indicating the respective transmitting and the second index indicating the respective receiving antenna element, both indices i,j lying between 1 and N, wherein N is the number of the at least two antenna elements; and for determining a factor |B n | with n=1 to N for an amplitude correction for each of the N antenna elements based on the determined gains Δ ij a and on equations:  B n  =  x 1     y n   x n     y 1  , wherein x n is the transfer function of the transmit branch of the n th antenna element and wherein y n is the transfer function of the receive branch of the n th antenna element, the determined gains Δ ij a corresponding to |x i ∥y j |.

Claim 12

A calibrating system for calibrating a smart antenna array with at least two antenna elements of a wireless access system using time division duplex, each antenna element including a transmit and a receive branch, the system comprising: a directional coupler in the transmit and the receive branch of each antenna element for coupling signals out of the transmit branches and for coupling signals into the receive branches; a physical connection between the coupler in the transmit branch of each antenna element and the coupler in the receive branch of at least one other antenna element respectively; selection means for selecting in a predetermined order at least each of those transmit branches of antenna elements connected to a receive branch of an antenna element that is connected at the same time to a transmit branch of at least one other antenna element to be employed for transmitting broadcast messages in predetermined broadcast periods during which the respective other antenna elements are prevented from transmitting signals; and processing means for evaluating signals transmitted via said connections for obtaining calibration information to be used for calibrating the smart antenna array.

Claim 13

A calibrating system for calibrating a smart antenna array with at least two antenna elements of a wireless access system using time division duplex, each antenna element including a transmit and a receive branch, the system comprising: a directional coupler in the transmit and the receive branch of each antenna element for coupling signals out of the transmit branches and for coupling signals into the receive branches; a physical connection between the coupler in the transmit branch of each antenna element and the coupler in the receive branch of at least one other antenna element respectively; selection means for selecting in a predetermined order at least each of those transmit branches of antenna elements connected to a receive branch of an antenna element that is connected at the same time to a transmit branch of at least one other antenna element to be employed for transmitting broadcast messages in predetermined broadcast periods during which the respective other antenna elements are prevented from transmitting signals; and processing means for evaluating signals transmitted via said connections for obtaining calibration information to be used for calibrating the smart antenna array.

Claim 14

The calibrating system unit of claim 10 , wherein the processing means are designed for fixing a calibration phase for one of N at least two antenna elements to a value {circumflex over (B)} 1 ; evaluating transmitted and received signals by determining their phase differences Δ ij , the first index indicating the respective transmitting and the second index indicating the respective receiving antenna element, both indices i,j lying between 1 and N; and for determining the calibration phases {circumflex over (B)} 2 to {circumflex over (B)} N for the N−1 further antenna elements based on suitable equations {circumflex over (B)} j −{circumflex over (B)} i ={circumflex over (x)} i −{circumflex over (x)} j −(ŷ i −ŷ j ), the hat {circumflex over ( )} denoting the phase of the respective variable, wherein x i is the transfer function of the transmit branch of the i th antenna element and wherein y j is the transfer function of the receive branch of the j th antenna element, and based on suitably determined phase differences Δ ij , the phase differences Δ ij corresponding to {circumflex over (x)} i +ŷ j and the indices i,j lying between 1 and N.

Claim 15

The calibrating system unit of claim 10 , wherein the processing means are designed for evaluating transmitted and received signals by determining the gain Δ ij a of the respective received signal compared to the respective transmitted signal, the first index indicating the respective transmitting and the second index indicating the respective receiving antenna element, both indices i,j lying between 1 and N, wherein N is the number of the at least two antenna elements; and for determining a factor |B n | with n=1 to N for an amplitude correction for each of the N antenna elements based on the determined gains Δ ij a and on equations:  B n  =  x 1     y n   x n     y 1  , with n=1 to N, wherein x n is the transfer function of the transmit branch of the n th antenna element and wherein y n is the transfer function of the receive branch of the n th antenna element,