Enhanced passive intermodulation detection in wireless networks
Interference caused by passive intermodulation (PIM) can be automatically detected at receivers in a wireless telecommunications network, and the accuracy of PIM detection can be increased by de-weighting or ignoring time slots in which non-PIM interference is detected at a target receiver.
1. A method of automatically detecting passive intermodulation (PIM) interference at a target receiver in a cellular network, the method comprising:
receiving interference data over a time period for the target receiver;
determining whether the received interference data has at least one non-PIM characteristic;
applying a weighting factor to at least one time slot of the time period in which interference with the non-PIM characteristic is detected;
determining whether PIM interference is present at the target receiver by analyzing interference at the target receiver over the time period with the at least one weighted time slot;
receiving interference data over the time period for the plurality of receivers;
determining correlations between interference detected by the plurality of receivers and the target receiver in the time period;
determining a second time slot in the time period in which the correlations exceed a predetermined value; and
determining a second weighting factor based on the correlations;
wherein determining whether PIM interference is present in the second time slot includes applying the second weighting factor to the second time slot.
2. The method of claim 1 , wherein the at least one non-PIM characteristic is selected from a broadband interference characteristic, a low traffic level for one or more transmitter within 20 meters of the target receiver, and a periodicity characteristic.
3. The method of claim 1 , wherein the weighting factor is chosen from 1 and 0 based on a level of at least one of the correlations, and a weighting factor of 0 excludes an associated time slot from consideration when determining whether PIM interference is present at the target receiver.
4. The method of claim 1 , wherein determining whether PIM interference is present comprises:
determining intermodulation product information for a plurality of transmitters;
receiving downlink power information of the plurality of transmitters;
determining, using the intermodulation product information and the downlink power information, a Weighted Downlink Power (WDP) signal for an intermodulation product, the WDP signal including a plurality of expected power values; and
determining, using the WDP signal, a PIM Detection Assessment (PIMDA) score of the intermodulation product, wherein a value of the PIMDA score corresponds to interference generated by PIM.
5. The method of claim 1 , further comprising:
determining a plurality of receivers in the cellular network that are separated from the target receiver by a minimum distance.
6. The method of claim 1 , wherein the correlations are based on at least one of periodicity, frequency, and magnitude of interference.
7. The method of claim 1 , further comprising:
resolving the interference by repairing an RF cable connection in a signal path of the receiver, removing oxidation from a component of the receiver, or reducing the effect of a nonlinearity that causes PIM product reflections.
8. A system for automatically detecting passive intermodulation (PIM) interference at a target receiver in a cellular network, the system comprising:
one or more processors; and
memory storing instructions that, when executed by the one or more processors, cause the system to:
receive interference data over a time period for the target receiver;
determine whether the received interference data has at least one non-PIM characteristic;
apply a weighting factor to at least one time slot of the time period in which interference with the non-PIM characteristic is detected; and
determine whether PIM interference is present at the target receiver by analyzing interference at the target receiver over the time period with the at least one weighted time slot;
receive interference data over the time period for the plurality of receivers;
determine correlations between interference detected by the plurality of receivers and the target receiver in the time period;
determine a second time slot in the time period in which the correlations exceed a predetermined value; and
determine a second weighting factor based on the correlations, wherein determining whether PIM interference is present in the second time slot includes applying the second weighting factor to the second time slot.
9. The system of claim 8 , wherein the at least one non-PIM characteristic is selected from a broadband interference characteristic, a low traffic level for one or more transmitter within 20 meters of the target receiver, and a periodicity characteristic.
10. The system of claim 8 , wherein the weighting factor is chosen from 1 and 0 based on a level of at least one of the correlations, and a weighting factor of 0 excludes an associated time slot from consideration when determining whether PIM interference is present at the target receiver.
11. The system of claim 8 , wherein determining whether PIM interference is present comprises:
determining intermodulation product information for a plurality of transmitters;
receiving downlink power information of the plurality of transmitters;
determining, using the intermodulation product information and the downlink power information, a Weighted Downlink Power (WDP) signal for an intermodulation product, the WDP signal including a plurality of expected power values; and
determining, using the WDP signal, a PIM Detection Assessment (PIMDA) score of the intermodulation product, wherein a value of the PIMDA score corresponds to interference generated by PIM.
12. The system of claim 8 , wherein the instructions executed by the one or more processors further cause the system to:
determine a plurality of receivers in the cellular network that are separated from the target receiver by a minimum distance.
13. The system of claim 8 , wherein the correlations are based on at least one of periodicity, frequency, and magnitude of interference.