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Considerations to Reduce Passive Intermodulation (PIM)

Posted by James Donovan on 21 June 2017 Connect with James on LinkedIn Estimated reading time: 2 minutes

For a wireless cellular network to achieve its full operating potential, each sector within the network must perform up to its design standard. Reducing Passive Intermodulation (PIM) is a key component of maintaining an efficient network.

When this does not occur, the economic impact to the service provider can be substantial:

  • Lost revenue at that site
  • Customer dissatisfaction and churn
  • Increased infrastructure cost
  • Reduction in cell site coverage area

To achieve the full operating potential of each node in the network, each Radio Frequency (RF) component and interconnection of RF path components must be properly installed, verified and maintained to insure optimum performance over time.


Understand the RF Path To Maximize Performance

Viewed from the RF perspective, to maximize performance, it is essential that:

  • The carrier signals be efficiently propagated from the transmitter output through the RF path components with minimum loss and distortion.
  • Upon reception of the RF signal from the handset at the base station antenna, the signal must be efficiently propagated back to the base station receiver.
  • Interference/noise at the base station receiver within the frequency band of the handset uplink signals must be lower in magnitude than the receiver noise floor.

There are more components than ever in the RF path; each additional component is another potential source of signal degradation. All of these components contribute to INCREASING system Insertion Loss and REDUCING the overall Return Loss value, which simply stated means “The system performance is getting worse”.

Wireless operators have invested a lot of money into 3G and 4G networks and will continue to do so for the next generation of technologies. These investments are often overlaid on the existing network, utilizing existing tower equipment such as coaxial feeder cable, filters and base station antennas.


How to Fix Signal Degradation

Operators are increasingly taking steps to avoid potential signal degradation that can result from overlays, especially when adding new frequency bands. Passive Intermodulation (PIM), being one of the causes of signal degradation, is enough of an issue today that many operators are deploying PIM testing equipment to the field to confirm PIM performance of the site.

The net result? The incidence and cost of PIM is no longer simply a nuisance, it is a critical threat to network efficiency, channel capacity, and bottom line profit.

Get certified to avoid these issues with the SP6160 course at the CommScope Infrastructure Academy, or view our other courses in our eBook here to better understand the passive infrastructure that underpins your network.