RSSI issue on only TDD sites

Experts: one support required.

We are facing RSSI issue on only TDD sites.

Can anyone suggest why?

All TDD sites or certain area?

Is it high all day or certain hours only?

UL RSSI, right ?

LTE band 800 ?


All time.

Is it specific for a site or neighbours have the same trend?

It may be due to Internal Interference.

Check hardware, mostly it would be due to Antenna Ports issue or RRU issue.

Checked all.

Antenna reoriented and checked?


Hardware swapped too.

Have you checked for External Illegal repeaters?

Yes, checked - no repeaters.

GPS alarms?

No GPS alarms.

Interference Issue in TDD (due to Propagation Delay)
Overreaching Down Link signals from one eNode B to another creates strong interference in uplink (in TDD)
Also, these signals are not restricted by Earth’s Curvature and travel large distances due to Duct Propagation
ToF interference:
• Affects TDD systems only
• Aggressor cell’s DL transmission affects victim cell’s UL transmission (UpPTS symbols and UL subframes)
• Interference occurs when
- Radio line-of-sight between aggressor and victim cells
- Insufficient antenna down-tilt or terrain height difference or atmospheric conditions
leading to ducting
• Aggressor and victim cells are separated by a distance larger than guard period (GP) propagation distance of special subframes (SSFs)
• Effect: UL & DL throughput is lowered
• DwPTS cannot be used for PDSCH Transmission in 2-5 configuration

Maybe time synchronization quality not good. Unsynchroniation, DL signals from nearby sites received by UL antenna of problem cells, caused high RSSI.

Please check GPS sync issue in site where all sectors are impacted with -92 UL RSSI.