Tuneable filter control method and base station
A method of controlling a tuneable filter ( 13 a ) of an antenna network ( 13 ) for use in a base station ( 1 ). The proposed method comprises: inputting an output of the antenna network ( 13 ) to a pre-distortion feedback path ( 5 ), inputting an output of the pre-distortion feedback path ( 5 ) and part of an original baseband signal to be transmitted by the base station ( 1 ) to a tuneable filter optimization algorithm ( 20 a ), controlling the tuneable filter ( 13 a ) in accordance with an output (CS) of said tuneable filter optimization algorithm ( 20 a ).
1. A method of controlling a tuneable filter of an antenna network for use in a base station, comprising:
inputting an output of the antenna network to a pre-distortion feedback path,
inputting an output of the pre-distortion feedback path and part of an original baseband signal to be transmitted by the base station to a tuneable filter optimisation algorithm,
controlling the tuneable filter in accordance with an output (CS) of said tuneable filter optimisation algorithm.
2. The method of claim 1 , wherein the tuneable filter optimisation algorithm implements a closed adaptive loop for controlling the tuneable filter.
3. The method of claim 1 , wherein controlling the tuneable filter involves controlling motor positions of motor means for adjusting filter elements of the tuneable filter.
4. The method of claim 1 , wherein controlling the tuneable filter comprises minimising an insertion loss of the tuneable filter.
5. The method of claim 1 , wherein the tuneable filter optimisation algorithm includes comparing in-phase and quadrature component signals of the original baseband signal with in-phase and quadrature component signals of the antenna network output.
6. The method of claim 1 , further comprising switching off transmission of the original baseband signal by the base station if the output of said tuneable filter optimisation algorithm indicates a deviation of the tuneable filter from a desired filter characteristic, in particular a filter band.
7. A radio transmitter having a forward signal processing path including an antenna network with tuneable filter, a pre-distortion feedback path, and a tuneable filter optimisation means, further comprising:
means for providing an output of the antenna network to the pre-distortion feedback path,
means for providing an output of the pre-distortion feedback path to said suitable filter optimisation means,
means for providing part of an original baseband signal to be transmitted to said tuneable filter optimisation means,
means for providing an output of the tuneable filter optimisation means to the antenna network for controlling the tuneable filter.
8. A base station for use in a radio communication system, comprising the radio transmitter of claim 7 .
9. Use of the base station of claim 8 in a Software-defined Radio communication system.
10. Use of the radio transmitter of claim 7 in a Software-defined Radio communication system.