What is PIM?
PIM (Passive InterModulation) occurs when signals from multiple high-power transmitters interact, typically with objects in the environment, creating nonlinear effects that interfere with the uplink signal and severely degrades throughput.
It’s not a new problem for the mobile network, but one that is difficult to identify and solve. Many mobile operators don’t know there is a PIM problem until after installation and site monitoring reports flag a performance issue.
Common Sources of PIM
Old cables, connectors and antennas
Diplexing new carriers onto existing cable runs
Cluttered cell towers and rooftops with many reflections
Frequency band combinations vulnerable to PIM
The Cost of PIM
With some simple math we can estimate the cost of PIM via its negative impact on traffic:
Unfortunately, when PIM occurs it usually affects more than just one site. Also this simple math does not incorporate subscriber churn due to slower speeds and reduced throughput. When these are taken into account, the financial impact of PIM is even larger.
Vulnerable band combinations
Close proximity of another operator's band created Triple beat and IM3 PIM. Accessibility and retainability suffered as a result.
Significant KPI improvements were achieved after the c-ONE PIM Canceler was deployed.
+41% Recovery in uplink accessibility & retainability
+22% Downlink throughput
+45% Uplink throughput
+53% Uplink traffic volume
-13% Drop rate
9dB RSSI improvement
6-9dB PIM cancelled
Benefits of ISCO's Solution
Eliminates potentially lengthy and costly troubleshooting on site to identify the source of PIM and resolve the issue. Often the fix is …
Higher Tx power: By removing PIM the downlink power can be increased, which leads to greater range and higher traffic capacity.
Versatile and Adaptive: This is a dynamic solution operating in real-time that adapts to the changing environment, and can cancel intermittent PIM interference (weather? Reflections from cars????)
Portable version enables…
How it Works
The c-ONE PIM Canceler from ISCO is deployed on the CPRI uplink between the BBU and the radio, and is often co-located with the BBU.
Advanced, patented algorithms operate on the raw I/Q data to detect, analyze, and remove PIM in real-time, regardless of its source.
PIM levels before and after ISCO cancellation