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Erlang Formula

Viewing 15 posts - 106 through 120 (of 181 total)
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  • #32967 Reply
    Deepak
    Guest

    Hi,

    Can you tell me the difference between LSR/QSR/TRD in traffic ?

    #32968 Reply
    aLOK bHARDWAJ
    Guest

    I am looking for the Erlang B formula and the theory behind it. I would be grateful if anyone who has this information to let me know

    #32969 Reply
    aashish ahuja
    Guest

    ALOK U HAVE TO OAR DEEP IN THE INTERNET TO FIND ERLANG B AND ITS APPLICATIONS THE THEORY BEHIND ERLANG B IS A LITTLE EASIER TO COMPREHEND I THOUGHT THAN A AND C .i CANNOT RECALL THE SITE BUT M DEFINITE;Y SURE THAT N A FEW HITS OF GOOGLE U WOD FIND IT..

    #32970 Reply
    kudos
    Guest

    hi there, is any1 know the LINUX source code to calculate the traffic.

    #32971 Reply
    shail
    Guest

    hi
    I would like to know how the switch planning is to start ?
    like start with 6BHCA in a typical GSM or CDMA n/w and you have any switch having different capacity what could be the subs can be connected ? what are the processor capacity ? how many Erlang is supported by switch etc. if a goood article is available on it pls provide.

    my mail id- shailendra_sitoke@ril.com

    #32972 Reply
    rajesh
    Guest

    Hai what does mean by GoS?

    #32973 Reply
    Erik
    Guest

    GoS = “Grade Of Service” = Blocking Probability Percentage
    You can check the internet (Google) for some material like the erlang B tables I found in Excel format recently.
    Some explanation is also given at the following URL: http://www.dcss.mcmaster.ca/~qiao/publications/erlang/newerlang.html

    Hope that helps.

    #32974 Reply
    Timothy
    Guest

    Code required:
    Hi there, if I know the number of circuits and the design GOS, how do I calculate the Critical Traffic.
    Thanks

    #32975 Reply
    Erik
    Guest

    Hi Tim,

    your question was a good exercise. I created the following macro in VBA (you can just copy/paste). It has the following characteristics:
    – limitation in the number of channels (creates buffer overflow if too many channels): I did not want to waste time solving this problem. You can have a look at it by yourself I guess.
    – configurable number of circuits
    – configurable GOS
    – configurable precision desired on the capacity (that’s the variable “dblDesiredPrecision”)
    – configurable range of research of the value.
    – optimised calculation of the factorials (we dont calculate the same values over and over again. Once is enough… and so much faster!!)

    In short, how is it calculated?
    1) You know that your capacity is more than zero
    2) you guess that your capacity is less than a certain value (I chose 1000000000 Erlangs)
    3) you try some value in between (dichotomia) and you look at the corresponding GOS. If the GOS obtained corresponds to some over-estimated capacity, your new range of research is now more than zero, and less than this value…
    4) repeat until the precision obtained is satisfying

    —————–
    Public Sub main()

    Dim resultCapacity, dblGradeOfService, dblNumCircuits As Double

    dblGradeOfService = 0.02 ‘”2%” is equivalent to “0.02”. You can modify this value if you have a different GOS
    dblNumCircuits = 10 ‘In this example, we use 10 circuits (channels)

    ‘capacity calculation
    resultCapacity = dblCapacity(dblGradeOfService, dblNumCircuits)

    End Sub

    Function factorial(ByVal myNumber As Double) As Double

    Dim i As Integer

    ‘keeps in memory the values already calculated of factorials. This avoids to recalculate the factorial each time
    Static varFactoBuffer As Variant
    If (IsEmpty(varFactoBuffer)) Then
    varFactoBuffer = Array(“1”, “1”)
    End If

    ‘we extend the factorial buffer and add the corresponding values
    For j = UBound(varFactoBuffer) To myNumber
    ReDim Preserve varFactoBuffer(j)
    varFactoBuffer(j) = varFactoBuffer(j – 1) * j
    Next j

    factorial = varFactoBuffer(myNumber)

    End Function

    Function GOS(ByRef capacity As Double, ByRef numCircuits As Double) As Double

    Dim denominator, numerator As Double
    Dim i As Long

    Dim capacityElevatedToPower As Variant
    capacityElevatedToPower = Array(“1”, capacity)
    For i = 1 To numCircuits
    ReDim Preserve capacityElevatedToPower(i + 1)
    capacityElevatedToPower(i + 1) = capacityElevatedToPower(i) * capacity
    Next i

    ‘ we calculate the denominator of the Erlang B formula
    For i = 0 To numCircuits
    denominator = denominator + capacityElevatedToPower(i) / (factorial(i))
    Next i

    ‘ we calculate the numerator of the Erlang B formula
    numerator = capacityElevatedToPower(numCircuits) / (factorial(numCircuits))

    GOS = numerator / denominator

    End Function

    Public Function dblCapacity(ByVal dblGradeOfService As Double, ByVal dblNumCircuits As Double) As Double
    ‘ The program will look for the desired value of the capacity between those limits
    Dim dblMinCapacity, dblMaxCapacity, dblEstimCapacity As Double
    dblMinCapacity = 0
    dblMaxCapacity = 1000000000
    dblEstimCapacity = (dblMaxCapacity + dblMinCapacity) / 2

    Dim dblEstimPrecision, dblDesiredPrecision As Double
    ‘ the precision (in Erlang) on the estimation of the capacity
    dblEstimPrecision = (dblMaxCapacity – dblMinCapacity) / 2
    ‘ precision desired on the capacity (in Erlang) calculation
    ‘ I chose 1E-6 because this sets the error to less than 1 Erlang on the total capacity of a normal national network
    dblDesiredPrecision = 0.000001

    While dblEstimPrecision > dblDesiredPrecision

    ‘ we estimate the GOS that can be obtained by the current value of the estimated capacity
    dblEstimGOS = GOS(dblEstimCapacity, dblNumCircuits)

    ‘ we improve our estimation of the capacity and we reduce the interval of research of the capacity
    If (dblEstimGOS > dblGradeOfService) Then
    dblMaxCapacity = dblEstimCapacity
    dblEstimCapacity = (dblMinCapacity + dblEstimCapacity) / 2
    Else
    dblMinCapacity = dblEstimCapacity
    dblEstimCapacity = (dblMaxCapacity + dblEstimCapacity) / 2
    End If

    ‘ we readjust the estimated precision because we have improved our knowledge of the value of the capacity
    dblEstimPrecision = (dblMaxCapacity – dblMinCapacity) / 2

    Wend

    dblCapacity = dblEstimCapacity

    End Function

    #32976 Reply
    Amod
    Guest

    Hi, Can you tell me how will you
    calculate Equip erlang for SDCCH?

    #32977 Reply
    BALAJI
    Guest

    Hi,

    Can anyone help me in calculating the Hourly channel utilization in a trunk group . If I know the value of Total Usage in CCS for the trunk group in an hour.

    Eg: If in a Trunk Group there are 30 channels & the total number usage is 79 CCS in an hou. Then how can I calculate the number of channels used in this particular hour.

    Best Regards,
    Balaji.

    #32978 Reply
    velayudhan
    Guest

    hi, i want to know what is the standard table to know the traffic in erlangs.Is there any table by name connypalm table ?

    #32979 Reply
    Erik
    Guest

    Hi… What do you mean “to know the traffic in Erlangs”? Capacity needs to be _calculated_ whereas traffic is just _recorded_
    At the OMC, or in any system to manage the raw counters and/or KPIs, you should be able to find some data that has been aggregated to let you know the usage of resources. Ask the people who manage this tool in your company, or some optimisers should be able to answer as well… But I think the name of the tables in this tool will be different from 1 company to another.

    #32980 Reply
    gautham
    Guest

    hi,

    I have this system which is supposed to make calls as per the time specified in a list with limitation in number of lines available. I would not like to miss out any numbers.

    Which would be the best algorithm for placing the call with minimum number of left over calls

    #32981 Reply
    gurmon
    Guest

    lots of questions – no answers…..

Viewing 15 posts - 106 through 120 (of 181 total)
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