Case studyTypical scenario · demonstration dataLTE · band 20Indoor · DASUplink noise rise · PIM
Uplink noise rise on a shared DAS: diagnosing passive intermodulation
Stationary test point in a building covered by a shared multi-operator DAS, LTE band 20 (800 MHz), uplink, downlink and simultaneous tests.
Root cause and correction
Root cause
- Third-order passive intermodulation generated by a faulty connector on the level 2 branch: as soon as the carrier is loaded, the intermodulation products raise the uplink noise floor by about 22 dB.
Corrective actions
- PIM test of the level 2 branch and location of the faulty point
- Replacement of the connector with a low-PIM model, with tightening torque checked
- Uplink noise check at no load and under load after the repair