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Reply To: congestion SDCCH

#37708
sbhattarai
Guest

HiPix.

sorry for the confusion. let me make it simple.
we have two sector sites in each side of the tunnel.Tunnel runs each west direction.Tunnel is about 2miles long.Each sector has 2 antennas.Rx lines are shared between GSM and TDMA.GSM is the primary one.As there are two tunnels tube and each tunnel tube has two lanes (no wall or barriers between lanes).Eaach sector we have two antnnas and 2 TMAs attached.TMAs recently installed after checking the weak UL in path balance and thought it may help to reduce the drop calls.

1.The rx signal level is different by about 8-10dB as we reach middle of the tunnel regardless of which lane we are during data collection.some time good signal at the middle of the tunnel and gets good handoff and the next time in the same area we have problem where signal drops 10dB lower.I was noticing few times that happens i had big truck before me where signal from other end of the site which MS was supposed to handoff can not see on time or even when it sees the signal is very weak than the serving sectors.
near field blockage may be the issues here?? antennas are at 10ft high in the wall mount..16dBi gain with 28deg hori.HBW.I have power control UL and DL made inactive and see what happens.

2. The TEMS data shows while locking on BCCH radio about -80dB to 100dB depending upon what time we drive and which lane we are at during the test.Again the sinal difference are mainly encountered at the middle of the tunnel where we should be ready to get handoff to…the cables are 1-5/8″ size.

I wil come back you with my findings and also i will do some test as you mentioned.
Thank you for your time.