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High SDCCH Traffic in LA Borders

Viewing 15 posts - 46 through 60 (of 62 total)
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    Pix, thanks for the quick answer. My question was related to an increase of SDCCH congestion due to an increae on the PCH blocking, but from you answer, I think the situation is the other way round, the SDCCH congestion limits the resources of the cell, demanding a paging retransmission due to lack of TCH resources to answer that call. As the PCH is answered by the RACH, there wouldn’t be a direct relation, but your answer gave me a new perspective. Thanks.


    hello montalli,

    i’m glad to give you new perspectives, but be careful because in your post there are *a lot* of misunderstandings !

    let’s be clear:
    cause –> consequence

    PCH congestion –> paging retransmission

    SDCCH congestion –> no paging retransmission, but call establishment failure (the subscriber has to dial again !)

    TCH congestion –> no paging retransmission, but call establishment failure (the subscriber has to dial again)

    As you can see, SDCCH and TCH congestions have the same consequences. However, a cell with sdcch congestion does not mean there is no TCH anymore. The congestion of SDCCH and TCH are totally uncorrelated !

    It is actually recommended to avoid sdcch congestion more than tch congestion. SDCCH is really important, and there is almost no queuing. Whereas TCH allocation can use a more elaborate queuing system, to avoid congestion.

    I hope I was clear… ๐Ÿ™‚



    can ay body help me to solve problem for location update rejection on two country border when trace is been done found there are alot of location update rejection due to message (PLMN is not allowed) or ( network failure),as checked there is raomimg agreement between operator but subscriber is not activate for roaming what is the solution



    if there is a location update rejection, it means that the MS performs a location update REQUEST. So the MS itself is not at fault.

    The IMSI of those MS are rejected by the neighbor HLR, because their IMSI’s are not allowed in the neighbor PLMN. Perform a test by manually asking the HLR to “check” such an IMSI, and see what’s its response. I don’t know if such a test is possible though.

    You can always perform an trace on the interface between your MSC and the distant MSC.



    what are the main perameters to be defined for the handovers of a call originated in a sector of any site which is operating on both 900 as well as 1800 bands(dual band network).At what time and which situation the handovers should happen.


    Pix said that PLMN not allwed appears by not being acceptable of a IMSI in a PLMN which that IMSI is not registered in that HLR or the HLR/VLR can’t get the response from source HLR.

    Then what will yo usay, If I say, I have many sample, that a SIM gets the message PLMN not allowed, from a network. but some minutae later it can register. and this happens many for those SIMs.



    This is definitely not my area of expertise, but I would say that the PLMN is defined as “Not allowed” in the SIM, yes if the SIM eventually tries to access that PLMN, the HLR accepts it.

    Strong chances are that I’m wrong though… IMO, the best option is to read the 3GPP, and check what it means when a PLMN is “not allowed” in a SIM. Can a SIM still attempts an IMSI ATTACH towards this particular PLMN ?



    Hi Esamoraglo,

    I have a question related to your High SDCCH Traffic:
    Are you using MSC In Pool in your network?



    Dear Pix

    1. I have read 3GPP & ETSI documentations ๐Ÿ™‚ around 300MB standards in this subject. and everything is OK on standards. But in real, the standards rules are not obeyed by the equipments !!! and this is much strange for me.

    2. Yes, it(they) can do IMSI attach. no problem. in deed after a minute everything becomes OK !

    3. If any guy works in a Mobile Network in country that there are more than 1 operator in same cities and these Operators don’t have Raming agreement with each other, please inform me. I may ask a question from him/her that will help me very much.

    4.the story is as below: (Excuse for long declaration in the stroy):
    there is 3 networks in the country(Op1,Op2,Op3). The problem is that: The MS of Op1 tries to Location update on other ones hugely !!! even they have coverage in the area.
    I check all details, detailed information, standards,…… I found many things and two of them are as below:

    1. When a MS comes into coverage or in turning on;(in automatic network selection); first checks for RPLMN (and then HPLMN asap); then HPLMN, then EHPLMN, then allowed prioritized, then sorting Quality and power (all stages: omitting Forbidden PLMNs)

    2. When a network respond “LU reject due to PLMN not allowed” in response to Location update request; then that PLMN will be registered in the “Forbidden PLMN list ” of MS (except HPLMN).
    this PLMN can be cleared just when the MS goes off/on or after long period of time or fulling the buffer (that I think it has capacity for 4 PLMNs).
    in this case the MS won’t request that PLMN again for location update.

    I said standard notes, but what happens in here is:
    related to No.1 : The MS (SIM of op1) requests other networks (Op2, Op3) in presence of good power level of op1 ARFCNs and those sites are Ok too. there is no try on them!!!
    related to No.2: the SIM of op1 tries on op2 and op3 and recieves “LU rejected due to PLMN not allowed”, but after some seconds it requests these networks again for LU !!!!! (maybe op2 or op3 are not written in forbidden list OR forbidden list can be cleared soon !!!!)

    This subject has brought huge amount of signalling traffic to BSC signallings of op2 and op3.
    Really I’m amazed, as I have check everything in stadards and everything must be OK; but the GSM rules and standards are not obeyed and performed by MSs and SIMs.

    Why ??????
    and declaration or explain or answer can be benefit for me. Really I have tested and checked everything I knew and was possible to be checked.



    i’ll ask my NSS colleagues, this issue is amazing.

    i’ll just ask one more thing: how did you analyse the problem ? With A interface trace on your competitor equiment ? Or with a drivetest MS ?
    How can you conclude that many of your MS’s are being rejected by op2 and op3 ?

    Thanks again for sharing your problem, it’s interesting.


    Dear Pix

    Yes, This is very much amazing and a challenge for mobile networks and standards.
    This subject is directly related to NSS, Core and SIM-Card mans. but the effect of it impact the Radio/BSS parts that makes the issue complicated.

    We perfom checking with using following lines: (and combine, compare, evaluate all them toghetehr)
    1. Using Protocol Analyzer and checking signalling over BSC/MSC in MAP,BSAP,… layer AND checking the cause, response, … of LU request, Roaming request,…
    2. Performing Driver Test with some SIMs and having Quality, Scanning, Signalling (Layer2,3,events,…) in attention
    3. Checking SIM Cards status with simple readers.

    So you see that everything is checked and all of them are compared with recommendations and standards (I was forced to read around 300MB docuemnts and standards)

    * again I say that, SIM-cards of Op1 must be rejected by Op2 or Op3 as they don’t have any roaming with eachother in neither same place or other places.
    The problem is that:
    (1)Why they are rejected in the registration of their own HPLMN!!!! sometimes ???
    (2) why in presence of Op1 good power and service, they send request to Op2 and Op3 ???
    (3) Why they try again and request again from Op2 and Op3 after some minutes that they had recieved rejection answer from them once !! ???
    These three issues deny any standard rule !!!

    * May be this subject is a big but hidden problem of some operators in the world. The guys who work in countries which 2 or 3 operators cover same areas without having roaming agreement, may suffer from it or have solution.

    Really my knowledge in this issue has come under question ๐Ÿ™‚

    riverstreamer [gmail]


    SDCCH congestion –> no paging retransmission, but call establishment failure (the subscriber has to dial again !)


    Oooh, i forgot about this.

    Riverstream, any news ?

    Bireswar: there should be paging retransmission… The MSC didn’t got any reply to its first paging, so it will send a second one.


    Dear Pix
    ๐Ÿ™‚ this is normal; I know you are busy and many times forget some issues ๐Ÿ˜‰ I had such experience in previous with you ๐Ÿ™‚
    For your info, NO RESULT, As I had explained in previous Message, All issues were checked in any available method and everything was checked with ETSI, 3GPP Standard and documents.
    this is not normal.
    I’m coming into this result that standards are not obeyed by Systems in this mean and because of huge traffic between operators and being this issue in hidden layers, nobody have attention to it, and just this pressure can be seen as a normal pressure for networks !
    I had no other conclusion.
    Anyway, I have leaved the company and has moved to Europe, so I am not in that job and in here Telecommunication/Mobile Jobs can not be found regardless of the engineer status ๐Ÿ™
    Bon Courage



    That’s too bad about you not working in telecoms anymore. But at least, you’re in europe. I hope you’re fine there.

    I’ll keep thinking about the roaming problem, I’m sure one day I’ll get to it… eventually ๐Ÿ™‚

Viewing 15 posts - 46 through 60 (of 62 total)
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