What is 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.

PIM

Frequency (MHz)

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 Passive InterModulation

The Cost of PIM

In our experience, a simple rule of thumb is that for each dB of Passive Intermodulation, throughput is reduced by approximately 8%. Hence a 6 dB PIM interferer can reduce throughput by half. In extreme cases, new sites cannot be put into service until the interference is resolved.

The reduction in throughput directly impacts revenue. Indirectly, slower speeds impact competitiveness and drives up subscriber churn. If you are interested in an impact analysis for your network, contact us for more information.

The Cost of PIM

Case Study

Vulnerable band combinations

The Problem

Close proximity of another operator's band created Triple beat and IM3 Passive InterModulation. Accessibility and retainability suffered as a result.

The Solution

Significant KPI improvements were achieved after the c-ONE PIM Canceler was deployed.

The Outcome

+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

c-ONE PIM Canceler

Benefits of ISCO's Solution

Avoid truck rolls

Eliminates potentially lengthy and costly troubleshooting on site to identify the source of PIM and resolve the issue. The c-ONE PIM Canceler works on the CPRI link so it does not require access to the cell site.

Higher Tx power

When the interference is removed, the downlink power can be increased. The stronger signal quality 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. Specific frequencies are not hard-coded into the algorithm.

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

ISCO PIM Canceller

PIM Cancellation Resources

APP NOTE

Restore Service Immediately While You Permanently Resolve PIM

DATA SHEET

C-ONE PIM Canceller Data Sheet

APP NOTE

PIM Best Practices

APP NOTE

Network Optimization for 5G

Want to learn more about
PIM cancellation?