Integrated intermodulation detection sub-system for telecommunications systems

• US 9,036,486 B2
• Filed: 09/17/2012
• Issued: 05/19/2015
• Est. Priority Date: 09/16/2011
• Status: Active Grant

• Current Assignee: Andrew Wireless Systems GmbH (CommScope Holding Company, Inc.)
• Original Assignee: Andrew Wireless Systems GmbH (CommScope Holding Company, Inc.)
• Inventors: Maca, Gregory Allan, Vetter, Udo-Michael
• Primary Examiner(s): Chriss, Andrew
• Assistant Examiner(s): Preval, Voster
• Application Number:
  US13/978,966
• Publication Number:
  US 20140119197A1
• Time in Patent Office: 974 Days
• Field of Search: 370/241
• US Class Current: 370/241
• CPC Class Codes: H04B 17/0085 using test signal generators
• CPC Class Codes: H04B 17/11 for calibration
• CPC Class Codes: H04B 17/14 of the whole transmission and reception path, e.g. self-test loop-back
• CPC Class Codes: H04B 17/17 Detection of non-compliance or faulty performance, e.g. response deviations H04B17/18 takes precedence
• CPC Class Codes: H04B 17/19 Self-testing arrangements
• CPC Class Codes: H04B 17/327 Received signal code power [RSCP]
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04B 7/15 Active relay systems
• CPC Class Codes: H04L 43/50 Testing arrangements
• CPC Class Codes: H04W 24/06 Testing, supervising or monitoring using simulated traffic
• CPC Class Codes: H04W 84/047 using dedicated repeater stations

Abstract

Certain aspects are directed to an intermodulation detection sub-system. The intermodulation detection sub-system includes a test signal generation module, at least one intermodulation detection device, and a controller. The test signal generation module is integrated into a unit of a telecommunications system. The test signal generation module is configured to provide a test signal to a remote antenna unit of the telecommunications system. The intermodulation detection device is integrated into the telecommunications system. The intermodulation detection device is configured to detect intermodulation products generated by mixing a first signal component and a second signal component of the test signal. The controller is integrated into the unit. The controller is configured to control the test signal generation module and the at least one intermodulation detection device.

Claims

1. An intermodulation detection sub-system, comprising:

a controller integrated into a unit of a telecommunications system, wherein the controller is configured to control a test signal generation module and at least one intermodulation detection device, and is further configured to select a first frequency of a first signal component of a test signal and a second frequency of a second signal component of the test signal, wherein the first frequency and the second frequency are selected such that the sum or difference of the first frequency and the second frequency is a third frequency of an intermodulation product in an uplink frequency band of the telecommunications system;

the test signal generation module integrated into the unit, wherein the test signal generation module is configured to provide the test signal to a remote antenna unit via a downlink path of the telecommunications system, wherein the test signal generation module comprises;

a first signal source configured to generate the first signal component of the test signal,

a second signal source configured to generate the second signal component of the test signal, and

a combiner configured to generate the test signal by combining the first signal component and the second signal component;

the at least one intermodulation detection device integrated into the telecommunications system, wherein the at least one intermodulation detection device is configured to detect the intermodulation product; and

a frequency scanner configured to detect an extraneous signal in a coverage area of the remote antenna unit, wherein the controller is further configured to select the first frequency and the second frequency such that the third frequency is different from a frequency of the extraneous signal;

wherein the at least one intermodulation detection device is integrated into at least one of the remote antenna unit or the unit.

2. The intermodulation detection sub-system of claim 1, further comprising at least one test switch, the at least one test switch configured to selectively couple the at least one intermodulation detection device to the downlink path of the telecommunications system or an uplink path of the telecommunications system, wherein the controller is further configured to generate a control signal for selectively coupling the at least one intermodulation detection device to the downlink path or the uplink path based on the intermodulation detection sub-system being in a test mode in which the test signal is provided to the downlink path.

3. The intermodulation detection sub-system of claim 1,

wherein the test signal generation module further comprises a test buffer communicatively coupled to the downlink path of the telecommunications system, the test signal generation module configured to generate the test signal using a test digital data set provided by the controller;

wherein the at least one intermodulation detection device further comprises a capture buffer communicatively coupled to an uplink path of the telecommunications system, the capture buffer configured to generate an uplink digital data set from an uplink signal traversing the uplink path;

wherein the controller is further configured to detect the intermodulation product in the uplink signal by correlating a model intermodulation product generated based on the test digital data set and the uplink digital data set from the capture buffer.

4. The intermodulation detection sub-system of claim 3, wherein the test buffer and the capture buffer are synchronized to a common reference clock.

5. The intermodulation detection sub-system of claim 1,

wherein the at least one intermodulation detection device comprises a power measurement device integrated into the remote antenna unit, wherein the power measurement device is configured to measure the power of the intermodulation product.

6. The intermodulation detection sub-system of claim 5, further comprising at least one path switch, the at least one path switch configured to selectively couple the test signal generation module to one of a plurality of downlink paths of the telecommunications system.

7. The intermodulation detection sub-system of claim 5, wherein the power measurement device comprises:

at least one filter between an antenna of the remote antenna unit and the power measurement device, wherein the at least one filter is configured to isolate the intermodulation product from the extraneous signal.

8. The intermodulation detection sub-system of claim 5, further comprising at least one terminating switch having a first configuration and a second configuration, the at least one terminating switch configured to selectively couple, in the first configuration, a portion of the downlink path of the telecommunications system to a terminating load and to selectively couple, in the second configuration, the portion of the downlink path to an input from a base station in communication with the telecommunications system, wherein the controller is further configured to generate a control signal for setting the at least one terminating switch to the first configuration based on the intermodulation detection sub-system being in a test mode in which the test signal is provided to the downlink path.

9. An intermodulation detection sub-system, comprising:

a test signal generation module comprising a first buffer, the first buffer communicatively coupled to a downlink path of a telecommunications system, the test signal generation module configured to provide a test signal to the downlink path;

a second buffer communicatively coupled to an uplink path of the telecommunications system, the second buffer configured to generate an uplink digital data set from an uplink signal traversing the uplink path; and

a processor communicatively coupled to the first buffer and the second buffer, wherein the processor is configured to detect an intermodulation product in the uplink signal traversing the uplink path by correlating a model intermodulation product and the uplink digital data set from the second buffer, wherein the model intermodulation product is generated based on a test digital data set from the first buffer representing the test signal.

10. The intermodulation detection sub-system of claim 9, wherein the test signal generation module is integrated into a unit of the telecommunications system and is configured to provide the test signal to a remote antenna unit of the telecommunications system.

11. The intermodulation detection sub-system of claim 9, wherein the test signal generation module comprises at least one of a periodic playback buffer, a digital-to-analog converter, an up-conversion module, or a power amplifier.

12. The intermodulation detection sub-system of claim 9, wherein the first buffer and the second buffer are synchronized such that the processor is configured to correlate data from the first buffer and data from the second buffer by correlating the model intermodulation product with the uplink digital data set.

13. The intermodulation detection sub-system of claim 9, wherein the processor is further configured to determine a distance from a non-linear impedance source generating the intermodulation product.

14. The intermodulation detection sub-system of claim 9, further comprising:

a downlink capture module communicatively coupled to the downlink path, the downlink capture module configured to generate a downlink digital data set from a downlink signal traversing the downlink path; and

an intermodulation modeling module configured to generate an additional intermodulation product from the downlink digital data set;

wherein the processor is further configured to detect the additional intermodulation product by correlating the additional intermodulation product and the uplink digital data set.

15. The intermodulation detection sub-system of claim 14, wherein the intermodulation modeling module is configured to apply a non-linear function to the data from the first buffer, the non-linear function modeling a modification to the test signal by a non-linear impedance source.

16. A method for detecting intermodulation products in a telecommunications system, the method comprising:

selecting, by a controller integrated into a unit of the telecommunications system, a first frequency of a first signal component of a test signal and a second frequency of a second signal component of the test signal, wherein the first frequency and the second frequency are selected such that the sum or difference of the first frequency and the second frequency is a third frequency of an intermodulation product in an uplink frequency band of the telecommunications system, wherein the intermodulation product is generated by a non-linear interface between components of the telecommunications system mixing the first signal component and the second signal component, wherein the controller the first frequency and the second frequency are selected such that the third frequency is different from a frequency of an extraneous signal detected in a coverage area of a remote antenna unit of the telecommunications system;

providing, by a test signal generation module integrated in the unit, the test signal to the remote antenna unit via a downlink path of the telecommunications system, wherein providing the test signal comprises;

generating the first signal component and the second signal component based on the controller selecting the first frequency and the second frequency, and

generating the test signal by combining the first signal component and the second signal component;

detecting, by at least one intermodulation detection device integrated into the telecommunications system, the intermodulation product.

17. The method of claim 16, further comprising coupling a portion of the downlink path to the test signal generation module prior to providing the test signal to the remote antenna unit, wherein the portion of the downlink path comprises a signal path between the unit and the remote antenna unit.

18. The method of claim 17, further comprising terminating an additional portion of the downlink path prior to a point at which the test signal is provided to the portion of the downlink path, wherein the additional portion of the downlink path comprises a signal path between a base station and the unit.