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congestion SDCCH

  • This topic has 54 replies, 1 voice, and was last updated 16 years ago by pix.
Viewing 15 posts - 16 through 30 (of 55 total)
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  • #37699

    hi manoj, u asked abt.some nokia parameters,pls rd down ths,giv me ur id,i will send u attachments.


    This report shows HO failure rates for all cells sorted by failure
    rate. Note that HO failure does not yet mean a dropped call because in most
    cases the call is successfully returned to the old channel.

    The target for an acceptable HO failure rate has to be set by the operator but
    generally it should be under 10% for normal sites.

    Tot Ho Fail % /hfr_1 Handover failure ratio over period
    HO att /ho_13a Handover attempts
    Drop call /dcf_6 Drop calls in handovers (BSC controlled incoming
    . and outgoing and intracell)

    Type Att Fail Blck NotA Drop Other
    MSC i ho_8 hfr_4a c4001 n/a n/a
    MSC o ho_9 hfr_5a c4055 c4037 c4107
    BSC i ho_10 hfr_6a c4011 n/a c4083
    BSC o ho_11 hfr_7a c4072 c4038 c4084
    Cell ho_12 hfr_3a c4019 c4036 c4085


    Type Handover type
    MSC i MSC controlled incoming HOs
    MSC o MSC controlled outcoming HOs
    BSC i BSC controlled incoming HOs
    BSC o BSC controlled outcoming HOs
    Cell Intra cell HOs

    Att Handover attempts
    Tot Fail Handover failure ratio of HO type
    Blck Handover blocked ratio
    NotA HO not allowed ratio
    Drop Drop call ratio
    Other Fail – Blck – NotA – Drop


    BTS HO failure rate
    between 20001227 and 20001227
    sorted by total HO fail %

    BTS Tot HO
    BCF Type Att Fail Blck NotA Drop Other Fail
    BSC (BTSid) % % % % % %
    —————– ——————————————- ——
    22722C MSC i: 354 11.2 0.0 – – 11.2 46.0
    22722 MSC o: 72 0.1 0.0 0.0 0.0 0.1
    BSC4335(54) BSC i: 1202 30.0 0.0 – 0.2 29.6
    BSC o: 426 0.9 0.0 0.0 0.4 0.7
    Cell : 190 3.8 0.0 0.0 1.0 2.8



    It would suffice if you tell me three things

    i)When does Blocked handover happen
    ii)When does NotA handover occur
    iii)ANd what specifically could be problem in “other ” category

    Thanks in advance


    manoj,HO are of various typs like tch-tch,sdcch-sdcch,sdcch-tch,normalreason for HO blck is in intracel ho if channel nt th same channel may b seized successfl.,after chang ho 2 xternal ie if A interface ckt. changes.manoj c4001 like r counters.



    Yogesh what about Not Allowed and “Others”


    I am facing problem regarding drop TCH(>10 %) but SDCCH drop rate,TCH blocking,CSSR and HSR are in controll so can anybody tell me the reason and solutions


    Handover depends on how many reasons



    Sandeep – Handover depends upon the foll reasons :

    1. Quality
    2. Interference
    3. Rxlev
    4. Timing Advance
    5. Congestion

    This is in the order of priority


    I am getting high amount of drop calls in the tunnel where there are sectors pointing each other from each side of the tunnel.The circular polarized antenna with 16dBi gain, 28degree horizontal beamwidth is pointing toward the tunnel.Antennas are placed 1ft off of the tunnel wall.There are two lanes for vehicles moving in the same direction and the test drive shows totally different signal strength.Depending upon which lane we collect the TEMS data shows significant different in signal strength.The sector has only 2 radios. second radio is hopping and we tried to make hopping off and even tried blocking the second radio and drove only with BSCCH radio with handoff parameter change but the site is popping up in worst performer list? Appreciate for your input.we had over 200ft cable run and we do have TMAs and the path balance is few dB hot in uplink already..any suggestion what we should look to fix very low retainability?? Thanks


    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 ?



    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.

    Muziwenkosi Reginald

    GPRS//EDGE QUESTION ON poor call setup success rate where calldrop is high.

    On a cell with more than 1 TRX’s where ;EDGE BCCH radio.

    1. what is the std setting for PWWRED on each radio for optimul service???
    2.wht is th maxGMSKoutput for the EDGE-RADIO vs PWRRED on de BCCH RADIO for optimul service


    hello with all,
    I would like to know what is at the origin of the cuts of communication, the scrambled communications, periodic silences in the communications. and say to me what it is that a “metal communication”. I think well that you will make a success to understand me because I do not speak well English but rather French. thank you to answer me quickly.

    Sandeep Saraf

    Why do handover failure occur as there is no freq.problem, co co bsic bcch,no hardware problem and no congestion


    Hi Sandeep Saraf,
    yes handover failure mostly occur if there is freqency/BSIC problem (co co bsic bcch). Mobile has some time for decoding all information from neighbouring cells. Due to this fact sometimes could happen, that MS report wrong BSIC. Suddenly increase of HO failure could be due to hardware problem (one of the TRX is wrong, one of diversity is connect to the wrong antenna-direction). But also wrong parameter setting could be reason for HO failure. For example if HO access min. is to low. If you have limit for number of HO between two cells (in case of ping pong HO – HO margin between two cell is 0, or wrong settings of HCS) there is also a lot of unsuccessful HO.


    Hi Sbhattarai,

    Your case is indeed interesting. Can u tell me the following :

    1. How much power in watts per carrier are u pumping ? U can use combiner bypass to boost rxlev over a distance ?

    2. What make of bts are u using ?

    3. Try reducing the rxlev access, cell-reselection, and inteference averaging parameters on both the sectors for faster handover.

Viewing 15 posts - 16 through 30 (of 55 total)
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