Active antenna system and methods of determining intermodulation distortion performance

Patent metadata

Field	Value
Publication number	US-10067171-B2
Application number	US-201515129746-A
Country	US
Kind code	B2
Filing date	Apr 8, 2015
Priority date	Apr 8, 2014
Publication date	Sep 4, 2018
Grant date	Sep 4, 2018

Abstract

An active antenna test system comprising an active antenna unit comprising: a test signal generator arranged to generate at least a first test signal and at least one second test signal; a plurality of transmitter modules operably coupled to the test signal generator wherein the plurality of transmitter modules are arranged to simultaneously process the first test signal and at least one second test signal to produce at least one radio frequency test signal therefrom; and at least one receiver module arranged to process one or more signals falling in at least one spectral band determined to be susceptible to intermodulation distortion products caused by the at least one radio frequency test signal being generated from the first test signal and at least one second test signal; and an intermodulation determination module operably coupled to the at least one receiver module and arranged to determine a first received intermodulation performance. A first transmitter module of the plurality of transmitter modules is operably uncoupled from the test signal generator and at least a first test signal and at least one second test signal re-applied to the remaining transmitter modules, such that the intermodulation determination module determines a second received intermodulation performance in order to determine an intermodulation distortion contribution of the first transmitter module therefrom.

First claim

The invention claimed is:

1. An active antenna system arranged to determine intermodulation distortion, the active antenna system comprising:
a test signal generator arranged to generate at least a first test signal and a second test signal;
a plurality of transmitter circuits arranged to generate at least one radio frequency test signal based on at least the first test signal and the second test signal, wherein the active antenna system is arranged to couple the plurality of transmitter circuits to the test signal generator in a first state, and wherein the active antenna system is arranged to uncouple a first transmitter circuit of the plurality of transmitter circuits from the test signal generator and to couple other transmitter circuits of the plurality of transmitter circuits to the test signal generator in a second state;
at least one receiver circuit arranged to process one or more signals comprising an intermodulation distortion product caused by the at least one radio frequency test signal; and
an intermodulation determination circuit operably coupled to the at least one receiver circuit and arranged to determine an intermodulation distortion contribution of the first transmitter circuit based on at least a first intermodulation performance associated with the first state and a second intermodulation performance associated with the second state.

2. The active antenna system of claim 1 , wherein the active antenna system is arranged to uncouple a second transmitter circuit of the plurality of transmitter circuits from the test signal generator and to couple the remaining transmitter circuits of the plurality of transmitter circuits to the test signal generator in a third state.

3. The active antenna system of claim 2 , wherein the intermodulation determination circuit is configured to determine an intermodulation distortion contribution of the second transmitter based at least partly on a third intermodulation performance associated with the third state.

4. The active antenna system of claim 2 , wherein at least one processor is arranged to rank transmitter circuits of the plurality of transmitter circuits in response to their respective determined intermodulation distortion contribution.

5. The active antenna system of claim 1 , wherein the test signal generator is arranged to at least generate the first test signal and the at least one second test signal while normal traffic routed through the active antenna system is disabled.

6. The active antenna system of claim 1 , wherein the test signal generator is arranged to perform one or more of the following:
generate at least one standardised test signal; or
generate at least one test signal with at least one characteristic of an air interface of the active antenna system.

7. The active antenna system of claim 1 , wherein the intermodulation determination circuit comprises a Fast Fourier Transform circuit arranged to determine at least a magnitude associated with the intermodulation distortion product.

8. The active antenna system of claim 7 , wherein the intermodulation determination circuit is further arranged to measure a power level and frequency associated with the intermodulation distortion product.

9. The active antenna system of claim 1 , wherein the at least one receiver is configured to be tuned to select a predetermined frequency spectrum susceptible to the intermodulation distortion product.

10. The active antenna system of claim 1 , wherein at least one processor is arranged to adjust a parameter of at least one of the first transmitter circuit or the at least one receiver circuit in response to the determined intermodulation distortion contribution of the first transmitter circuit to thereby cause an intermodulation level of signals processed by the active antenna system to be reduced.

11. The active antenna system of claim 10 , wherein the at least one processor is arranged to adjust the parameter by applying at least one of: an attenuation factor, a gain factor, a beamform weight adjustment, a filter adjustment, a digital predistortion adjustment, or a frequency plan of used frequencies applied to at least one live air interface traffic signal processed by the active antenna system.

12. The active antenna system of claim 1 , wherein an interface is operably coupled to the test signal generator such that the test signal generator is remotely controllable via the interface.

13. A method of determining intermodulation performance in an active antenna system, the method comprising:
generating, with a plurality of transmitter circuits coupled to a test signal generator configured to provide at least a first test signal and a second test signal, at least one radio frequency test signal from at least the first test signal and the second test signal;
determining, by an intermodulation determination circuit, a first intermodulation performance based on the at least one radio frequency test signal;
generating, with a first transmitter circuit of the plurality of transmitter circuits uncoupled from the test signal generator and the remaining transmitter circuits of the plurality of transmitter circuits coupled to the test signal generator, at least one second radio frequency test signal from at least the first test signal and the second test signal;
determining, by the intermodulation determination circuit, a second intermodulation performance based on the at least one second radio frequency test signal; and
determining an intermodulation distortion contribution of the first transmitter circuit based on the first intermodulation performance and the second intermodulation performance.

14. The method of claim 13 , further comprising determining an intermodulation distortion contribution for a second transmitter of the plurality of transmitter circuits based at least partly on a third intermodulation performance associated with the second transmitter circuit being uncoupled from the test signal generator and the remaining transmitter circuits of the plurality of transmitter circuits being coupled to the test signal generator.

15. The method of claim 13 , wherein the first transmitter circuit is coupleable to the intermodulation determination circuit by way of at least one receiver circuit, and the method further comprises adjusting a parameter of at least one of the transmitter circuit or the at least one receiver circuit to thereby reduce intermodulation distortion in the active antenna system.

16. The method of claim 15 , further comprising:
determining an updated intermodulation performance of at least one of the plurality of transmitter circuits or the at least one receiver circuit following the adjusting the parameter; and
performing a further adjustment of the parameter in response to the updated intermodulation performance.

17. An active antenna system arranged to determine intermodulation distortion, the active antenna system comprising:
a plurality of receiver circuits;
a beamformer circuit configured to generate an aggregated signal from output signals of the plurality of receiver circuits; and
an intermodulation determination circuit operably coupled to the beamformer circuit, the intermodulation determination circuit configured to determine an intermodulation distortion contribution of a first receiver circuit of the plurality of receiver circuits based at least partly on a first intermodulation distortion associated with a first state and a second intermodulation distortion associated with a second state,
wherein the plurality of receiver circuits are coupled in the first state, and wherein the firs

Assignees

• Analog Devices Global

Inventors

• O'Keeffe Conor
• Moore Joe

Classifications

• G01R29/10 Primary

  Radiation diagrams of antennas · CPC title

• H04B17/12

  of transmit antennas, e.g. of the amplitude or phase · CPC title

• H04B1/0466

  Fault detection or indication (H04B1/0483 takes precedence) · CPC title

• H04B17/102

  Power radiated at antenna · CPC title

• H01Q1/00

  Details of, or arrangements associated with, antennas (arrangements for varying orientation of directional pattern H01Q3/00) · CPC title