Passive intermodulation (PIM) testing in distributed base transceiver station architecture

Patent metadata

Field	Value
Publication number	US-10608919-B2
Application number	US-201715430211-A
Country	US
Kind code	B2
Filing date	Feb 10, 2017
Priority date	Feb 19, 2016
Publication date	Mar 31, 2020
Grant date	Mar 31, 2020

Abstract

A passive intermodulation (PIM) tester is provided. The PIM tester includes at least one interface to couple the tester to a front-haul communication link used for communicating front-haul data to a remote radio head (RRH) having one or more antenna ports. The PIM tester includes a programmable processor, coupled to the interface, configured to execute software, wherein the software is operable to cause the tester to do the following: identify at least one tone in at least one downlink band of the remote radio head, wherein potential PIM products may appear in at least one uplink band of the remote radio head in response to the identified at least one tone; inject the identified at least one tone in the at least one downlink band of the remote radio head; and monitor the at least one uplink band for the potential PIM products from the injected at least one tone.

First claim

The invention claimed is:

1. A method of testing for passive intermodulation (PIM) for a base station, the method comprising:
detecting cell configuration data for at least one cell of the base station;
prompting a user to identify at least one downlink band for at least one detected cell;
identifying tones in the at least one downlink band for the at least one detected cell, wherein potential PIM products may appear in at least one uplink band of the base station in response to the identified tones;
injecting the identified tones in the at least one downlink band of the base station;
monitoring the at least one uplink band for the potential PIM products from the injected tones;
recording the existence of the potential PIM products when detected; and
wherein identifying tones comprises pairing each tone in a plurality of downlink bands with the other tones in the plurality of downlink bands and calculating potential PIM products based on each pair of tones.

2. The method of claim 1 , wherein detecting cell configuration data comprises detecting a cell ID from baseband data transmitted on an optical link between a baseband unit (BBU) and a remote radio head (RRH).

3. The method of claim 2 , wherein the baseband data is transmitted using one of a CPRI interface, an OBSAI interface, and an ORI interface.

4. The method of claim 1 , wherein prompting the user to identify at least one downlink band comprises prompting the user for an RF channel number.

5. The method of claim 4 , wherein prompting the user further comprises presenting a list of downlink bands associated with a detected cell ID.

6. The method of claim 1 , wherein identifying tones in the at least one downlink band includes; and
identifying a subset of the pairs of tones to be injected in the at least one downlink band to test for the potential PIM products in the uplink band.

7. The method of claim 6 , wherein identifying a subset of pairs of tones includes identifying a pair of tones that produces a lowest order PIM product that falls within the uplink band.

8. The method of claim 1 , wherein identifying tones comprises selecting pairs of tones in the same downlink band.

9. The method of claim 1 , wherein identifying tones further comprises determining whether the calculated, potential PIM products fall in any of the at least one uplink bands of the base station.

10. The method of claim 1 , wherein injecting the tones comprises injecting a first tone on one downlink band and a second tone on a second downlink band.

11. The method of claim 1 , wherein monitoring the at least one uplink band for the potential PIM products comprises:
tuning a narrowband receiver around a frequency of the potential PIM product;
applying a Fast Fourier Transform (FFT) to the data from the narrowband receiver; and
checking for a signal magnitude above a selected threshold.

12. The method of claim 11 , and further including averaging the output of the FFT over time.

13. The method of claim 1 , and further repeating the process of injecting the identified tones and monitoring the at least one uplink band a plurality of times before recording the existence of the potential PIM products.

14. The method of claim 1 , wherein injecting the identified tones comprises injecting one of carrier wave tones, modulated tones, or a signal with a cyclostationary signature.

15. The method of claim 1 , wherein injected tones are modulated with one of on-off, phase or frequency modulation.

16. The method of claim 1 , wherein monitoring the at least one uplink band for PIM products comprises monitoring an uplink channel that is paired with at least one of the at least one downlink band.

17. A passive intermodulation tester, comprising:
at least one interface to communicatively couple the tester unit to a front-haul communication link used for communicating front-haul data to a remote radio head (RRH) having one or more antenna ports;
a programmable processor, coupled to the interface, configured to execute software, wherein the software is operable to cause the tester to do the following:
identify at least one tone in at least one downlink band of the remote radio head, wherein potential PIM products may appear in at least one uplink band of the remote radio head in response to the identified at least one tone;
inject the identified at least one tone in the at least one downlink band of the remote radio head;
monitor the at least one uplink band for the potential PIM products from the injected at least one tone;
record the existence of the potential PIM products when detected; and
wherein identifying at least one tone comprises pairing each tone in a plurality of downlink bands with the other tones in the plurality of downlink bands and calculating potential PIM products based on each pair of tones.

18. The tester of claim 17 , wherein the at least one interface and programmable processor are implemented on a circuit board that is adapted for insertion into an RF test system.

19. The tester of claim 18 , wherein the at least one interface is adapted to use optic equipment in the RF test system to communicate over the front-haul communication link.

20. The tester of claim 17 , wherein identifying at least one tone comprises identifying pairs of tones in the at least one downlink band including:
identifying a subset of the pairs of tones to be injected in the at least one downlink band to test for the potential PIM products in the at least one uplink band.

21. The tester of claim 20 , wherein identifying a subset of the pairs of tones includes selecting a pair of tones that produces a lowest order PIM product for the uplink band.

22. The tester of claim 17 , wherein identifying at least one tone further comprises determining whether the calculated, potential PIM products fall in any of the at least one uplink bands.

23. The tester of claim 17 , wherein injecting the at least one tone comprises injecting a first tone on one downlink band and a second tone on a second downlink band.

24. The tester of claim 17 , wherein injecting the at least one tone comprises injecting one of carrier wave tones, modulated tones, or a signal with a cyclostationary signature.

25. The tester of claim 17 , wherein injected tones are modulated with one of on-off, phase or frequency modulation.

26. A program product for passive intermodulation testing, tangibly stored on a non-transitory storage medium, comprising instructions operable to cause at least one programmable processor to:
identify pairs of tones in at least one downlink band for at least one cell, wherein potential PIM products may appear in at least one uplink band of the remote radio head in response to the identified tones;
inject the identified pairs of tones in the at least one downlink band of the remote radio head;
monitor the at least one uplink band for the potential PIM products from the injected pairs of tones; and
record the existence of the potential PIM products when detected; and
wherein identifying pairs of tones in the at least one downlink band includes:
calculating the potential PIM products using the pairs of tones; and
identifying a subset of the pairs of tones to be injected in the at least one downlink band to test for the potential PIM products in the at least one uplink band.

27. The program product of claim 26 , wherein identifying a subset of the pairs of tones inc

Assignees

• Commscope Technologies Llc

Inventors

• Beck Andrew E
• Gravely Thomas B
• Boyle Patrick

Classifications

• H04W88/085

  Access point devices with remote components · CPC title

• H04L43/50 Primary

  Testing arrangements · CPC title