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High SDCCH Establishment failure rate

Viewing 7 posts - 1 through 7 (of 7 total)
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  • #50050 Reply

    this kind of behaviour is happening when dealing with Ericsson n/w.
    i don´t know what can cause such a bad performance, since i have never faced this before.
    counters used are ccalls and cmsestab:((ccalls – cmsestab) / ccalls)

    is it ok? i´ve heard that these two counters are not “synchronised” since one in RLC related and the other is under SS7 protocol, and at the end it may give a result that is worse than the perceived by the user.

    #50051 Reply

    you have to find out which events these two counters are counting : exactly, which ABIS interface or which A interface messages are counted ?

    #50052 Reply

    According to the KPI document in use:
    from the BSS side: message in question is CHANNEL REQUIRED, BTS => BSC.
    from the NSS side: an SCCP CONNECTION CONFIRMED message.

    is it mentioned that due to the fact that these are under two different protocols, indicator may present values that do not report the end user perception.

    the indicator is according to the vendor´s documentation.

    the main challenge is to identify possible reasons that justify this bad behaviour and solution to make it better.

    #50053 Reply

    this indicator measures the SDCCH ASSIGNMENT FAILURE, not the call setup failure !! there are plenty of messages after the connection request that are needed in order to end the call setup.

    what problem might lead to high value of S.A.F rate ?
    3 typical causes :
    – congestion (if there is sdcch congestion, the MS will try to retransmit the channel request several times : for one “real” attempt, you count three attempts, therefore three failures : instead of measuring 2% congestion, you measure 6% congestion…)
    – radio
    – system failures

    but also :
    – dupllicate BSIC BCCH
    – duplicate BSIC TCH
    – DUMMY RACH (generated by the BTS noisy EM emissions)
    – ABIS or ATER over satelllite : by the time the answer ” IMMEDIATE ASSIGNMENT” arrives to the MS, the MS has already sent another CHANNEL REQUEST. This leads to 2 requests for 1 success ==> 50% failure.


    #50054 Reply

    I like to know about Frequency Loading. If we have 9 ARFCNs for hopping, we can use 9 MAIO(0-8).Can we go for configuration more than 4x4x4 by repeting MAIOs and using different HSNs.Is it is feasible, If it is then what will be the effect in Network.

    #50055 Reply


    How we can find the problem of low SDCCH Establishment Rate due to NSS side

    #50056 Reply

    we have SDCCH_ESTB degradation on the LAC border due to increasing location area updating. we set all the parameters but no result gained!!! Either same result from E-tilt.. could you help me to overcome this issue. i should add we are working on NSN systems.

Viewing 7 posts - 1 through 7 (of 7 total)
Reply To: High SDCCH Establishment failure rate
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