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Reply To: congestion SDCCH


hi sbhatarrai,

your case sounds interesting but the way you explain everything is very confusing for me…

let me recap. you have a BTS 2×2, each sector connected to one antenna. Each antenna is facing one side of the tunnel. There is over 200ft of feeder and a TMA for each antenna, to compensate for the feeder loss.

I note two different issues in your post :

1) you receive different RxLev depending on which lane you are ? You mean at a certain position in the tunnel, whether you are on the left lane or on the right lane, you receive different RxLev ? (lanes are separated by how many meters ? is there a wall in betwen the lanes ?)

2) both sectors are supposed to be covering the tunnel, but inside the tunnel, you do not receive a strong signal from either sectors ? therefore, you pick up the signal from another BTS, located outside the tunnel. Is that correct ?

About 1) I don’t understand how it is possible, I need clarifications

About 2) Basically, it looks like there is no power being emitted from your antennas. “Worst Performer” list means what ? Low RxLev ? I’m sorry, I don’t recall this term in Tems Investigation.
Can you shutdown the second TRX for each sector and lock your TEMS mobile on one BCCH (say, sector 1). Drive in the whole tunnel, and see where is the best coverage. Do the same for sector 2 : drivetest he whole tunnel on the second BCCH.
… What is the max. rxlev you get ?
… Are the two sectors inverted ?
… How far do you get a coverage above -80dBm ?

The first thing that pops up in my mind : 200ft of cables. Which cable did you use ? What are the dB losses ? Using a 7/8″, it should be about 4dB… I’m not sure you need a TMA to counter for the losses. Have you tried unplug the TMAs for a while ?