- This topic has 5 replies, 1 voice, and was last updated 10 years, 9 months ago by Mahesh khanna.
4th October 2006 at 00:09 #45893sbhattaraiGuest
we have two sectors serving from two sites from each side of the tunnel and we experiencing high drop calls. how we reduce this low retainability on the site where our two lane tunnel is about 17ft tall with two lanes.antenna are mounted on the wall as we enter the tunnel.Path balance looks fine.we are using ericsson system 1900 GSM.we changed the hihyst,lohyst,msrxmin and tried but still statistics is bad.BCCH and BSIC combination is fine,checked and double checked and again it is inside the tunnel.we have SDCCH uncombined configuration.sweep test for antenna system shows very clean.no alarams or faults in hardware noticed.Radios replaced but problem still there.the distance of tunnel is about 1.5mile where two sector of two sites are pointing each other to serve that distance.lot of traffic pass by (16ft truck…) antenna is circular polarization with 28deg Hori.BW with 16dBi gain.each time we drive the rssi level is totally changes..
there is any suggestion what we should change and try..thanks for the input.4th October 2006 at 01:05 #45894PixGuest
i don’t understand what happened to your previous post and my reply ! got deleted ?
can you please send me your TEMS logfile by email ? I hope it is not too big. Otherwise, can you describe the rxlev values depending on how far you are compared to the antenna ?
If you stay next to the antenna (let’s say 20m away in front of it), how much is the rxlev ?
email : pix_erlang (at) yahoo.fr4th October 2006 at 02:14 #45895sbhattaraiGuest
I send out another message just few minutes ago. If we measure rx level within 20m from the antenna we get about -51dB signal level or so. i will try to send you the log files from TEMS.
thank you for your time.4th October 2006 at 17:54 #45896EDWARDGuest
how does the HO statistic look like in these two sectors?? WHAT IS THE REASON FOR THE DROPPED CALLS ( LOW SS IN UL OR DL, HIGH RX QUAL).? DO THESE TWO ANTENAS BELONG TO DIFFERENT CELLS IN DIFFERENT BSCs? IS THERE A CURVE IN THE TUNNEL??? ANY OUTER CELL IS ALSO COVERING???17th October 2006 at 01:07 #45897EdwardGuest
Ho stats shows weak signal in UL and Both link, we put Tower mounted amp (TMAs) and now the path balance is ok.The two sites of two sectors which are in each side of the tunnel mouth are located in the same BSCs (no inter BSC handover involve).The two sites are loacated each end of the tunnel.Each tunnel side has two antennas Rx, and RX/Tx lines.Still have drop calls. Seems to be too much reflection in the tunnel…lots of traffic with big truck blocking but rx signal what we get out of the antennas seems to be very good..the tunnel is gradually goes down and slowly comes up..no sharp bend or anything like that.Any help will be appreciated.25th May 2010 at 12:09 #45898Mahesh khannaGuest
We are doing DMRC project. What is desired signal level in tunnel.
We are using LEAKY CO AXIAL CABLE:- CONSTRUCTION AND SPECIFICATIONS
RMC 50L RMC 50LM SERIES
we are to operatr GSM 900, 1800, CDMA 900.
What is the specified signal level