Method and apparatus for the detection of distortion or corruption of cellular communication signals
A system for troubleshooting signals in a cellular communications network, and in particular, for determining the cause of distortion or corruption of such signals, includes a robotic or other type of switch. The robotic switch can tap into selected uplink fiber-optic lines and selected downlink fiber-optic lines between radio equipment and radio equipment controllers in a wireless (e.g., cellular) network to extract therefrom the I and Q data. The selected I and Q data, in an optical form, is provided to an optical-to-electrical converter forming part of the system. The system includes an FPGA (Field Programmable Gate Array) or the like, and an analytic computer unit, or web server, and SSD (Solid State Drive) and magnetic disk storage, among other components of the system. The system analyzes the I and Q data provided to it, and determines the cause, or at least narrows the field of possible causes, of impairment to transmitted signals. The system includes a display which provides the troubleshooting information thereon for a user of the system to review, or other form of a report, and may communicate the analytical findings to a remote location over a public or private internet protocol network.
1. A method for use with a system including a radio equipment (RE) and a radio equipment controller (REC) being in communication through a medium having an uplink communication channel supporting uplink data communications from the RE to the REC, and a downlink communication channel supporting downlink data communications from the REC to the RE, the method comprising:
generating a first multi-tone continuous wave (CW) signal;
transmitting the first multi-tone CW signal having a first phase over the downlink communication channel;
receiving a second multi-tone CW signal, over the uplink communication channel, resulting from a passive intermodulation distortion (PIM) of the first multi-tone CW signal;
extracting uplink I/Q data from the second multi-tone CW signal;
obtaining a second phase using the uplink I/Q data; and
calculating a distance to a location of the PIM based on the first phase and the second phase.
2. The method of claim 1 , wherein the obtaining of the second phase using the uplink I/Q data includes taking an arctangent of the uplink I/Q data.
3. The method of claim 1 , wherein the calculating of the distance to the location of the PIM includes:
obtaining a time value based on the first phase and the second phase;
determining the distance using the time value and a velocity of propagation for the medium.
4. The method of claim 1 further comprises:
extracting downlink I/Q data from the first multi-tone CW signal; and
obtaining the first phase using the downlink I/Q data.
5. The method of claim 1 , wherein the medium is a wired medium.
6. The method of claim 1 , wherein the medium is a wireless medium.
7. The method of claim 1 , wherein the first multi-tone CW signal is a two-tone CW signal including a first tone having a first frequency and a second tone having a second frequency.
8. The method of claim 1 , wherein the first multi-tone CW signal is a three-tone CW signal including a first tone having a first frequency, a second tone having a second frequency, and a third tone having a third frequency.
9. The method of claim 8 , wherein the system includes an oscillator and the second multi-tone CW signal is a two-tone CW signal including the first tone having the first frequency and the second tone having the second frequency, and wherein the method further comprises:
receiving a third multi-tone CW signal, over the uplink communication channel, resulting from the passive intermodulation distortion (PIM) of the first multi-tone CW signal, wherein the third multi-tone CW signal is a two-tone CW signal including the first tone having the first frequency and the third tone having the third frequency;
extracting uplink I/Q data from the third multi-tone CW signal;
obtaining a third phase using the uplink I/Q data extracted from the third multi-tone CW signal;
determining an oscillator phase of the oscillator based on the second phase and the third phase; and
eliminating the oscillator phase when calculating the distance to the location of the PIM based on the first phase and the second phase.
10. The method of claim 9 , wherein the oscillator phase is a common phase difference of the second phase and the third phase.
11. A test device for use with a system including a radio equipment (RE) and a radio equipment controller (REC) being in communication through a medium having an uplink communication channel supporting uplink data communications from the RE to the REC, and a downlink communication channel supporting downlink data communications from the REC to the RE, the test device comprising:
a tone generator configured to generate a first multi-tone continuous wave (CW) signal;
a transmitter configured to transmit the first multi-tone CW signal having a first phase over the downlink communication channel;
a receiver configured to receive a second multi-tone CW signal, over the uplink communication channel, resulting from a passive intermodulation distortion (PIM) of the first multi-tone CW signal; and
a processor configured to extract uplink I/Q data from the second multi-tone CW sig, obtain a second phase using the uplink I/Q data, and calculate a distance to a location of the PIM based on the first phase and the second phase.
12. The test device of claim 11 , wherein the processor is configured to obtain the second phase using the uplink I/Q data by taking an arctangent of the uplink I/Q data.
13. The test device of claim 11 , wherein the processor is configured to calculate the distance to the location of the PIM by:
obtaining a time value based on the first phase and the second phase;
determining the distance using the time value and a velocity of propagation for the medium.
14. The test device of claim 11 , wherein the processor is further configured to:
extract downlink I/Q data from the first multi-tone CW signal; and
obtain the first phase using the downlink I/Q data.
15. The test device of claim 11 , wherein the medium is a wired medium.
16. The test device of claim 11 , wherein the medium is a wireless medium.
17. The test device of claim 11 , wherein the multi-tone CW signal is a two-tone CW signal including a first tone having a first frequency and a second tone having a second frequency.
18. The test device of claim 11 , wherein the multi-tone CW signal is a three-tone CW signal including a first tone having a first frequency, a second tone having a second frequency, and a third tone having a third frequency.
19. The test device of claim 18 , wherein the system includes an oscillator and the second multi-tone CW signal is a two-tone CW signal including the first tone having the first frequency and the second tone having the second frequency, and wherein:
the receiver is further configured to receive a third multi-tone CW signal, over the uplink communication channel, resulting from the passive intermodulation distortion (PIM) of the first multi-tone CW signal, wherein the third multi-tone CW signal is a two-tone CW signal including the first tone having the first frequency and the third tone having the third frequency;
the processor is further configured to:
extract uplink I/Q data from the third multi-tone CW signal;
obtain a third phase using the uplink I/Q data extracted from the third multi-tone CW signal;
determine an oscillator phase of the oscillator based on the second phase and the third phase; and
eliminate the oscillator phase when calculating the distance to the location of the PIM based on the first phase and the second phase.
20. The test device of claim 19 , wherein the oscillator phase is a common phase difference of the second phase and the third phase.