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Erlang Formula

Viewing 15 posts - 136 through 150 (of 181 total)
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  • 28th September 2005 at 09:32 #32997
    Erik
    Guest

    Hello “5”,

    Just look at the bottom of the page. You will find it in a message from Rommel.

    14th October 2005 at 10:58 #32998
    Ravipal Singh
    Guest

    Can anybody expain what is ss7 Link load capacity and what are the calculations to calculate the same

    21st December 2005 at 06:14 #32999
    busybee
    Guest

    can any one help me simulate a hard handoff in matlab???

    23rd December 2005 at 03:54 #33000
    korwilis
    Guest

    does any one can help me to the defenition between Rxlev and rx Quality?

    27th December 2005 at 08:38 #33001
    trafik_analiz
    Guest

    I advice you to visit an interesting web page about erlang used in Exchanges

    http://www.geocities.com/trafik_analiz

    27th December 2005 at 16:44 #33002
    Erik
    Guest

    Question from Korwilis was:
    “does any one can help me to the defenition between Rxlev and rx Quality?”

    RxLev is the level of received signal, measured in dBm. You generally measure 2 different RxLev:
    – Level of signal received by the mobile: (Downlink RxLev, or “DlRxLev”)
    – Level of signal received by the BTS (Uplink RxLev, or “UlRxLev”)

    The RxQual is a measure of the Bit Error Rate (BER). As above, you have DlRxQual and UlRxQual. Instead of following this indicator in terms of percentage, operators generally define “ranges” for the follow-up of the RxQual. Then they will follow some values between 0 (low error rate) and 7 (very high error rate).

    29th December 2005 at 10:11 #33003
    osprey
    Guest

    hi Erik

    Then what’s the different between SQI and RxQual?
    i’ve notice there’s RxQual dBm and RxQual %, what’s the difference?
    tq

    29th December 2005 at 18:26 #33004
    Erik
    Guest

    Hi Osprey,
    For “SQI” (Speech Quality Index), a document found on ericsson.com states that “SQI assesses the speech quality as perceived by the mobile station user. (…) The SQI values are based on bit error and frame erasure rates and their respective distributions”. So, SQI will be more relevant in terms of customer perception (perceived quality is strongly related to frame erasure rate) for the voice only. For the benchmarking of data services, SQI should not be used.

    For RxQual, it_can_NOT_be_in_dBm. It is either in percentage (but in this case, it’s more appropriate to call it “BER”) or in a scale of discrete integer values, often taken from 0 to 7, which reflects different ranges of the BER.

    Additional note: In both cases, BER or RxQual have no “unit”. Percentage is a format for numbers.

    If you see anything in “dBm”, it is a measure of power. So I guess you mistook RxQual and RxLev.

    30th December 2005 at 01:54 #33005
    osprey
    Guest

    hi Erik,
    Thanx for your explanation. yes, i’ve made a mistake. RxQual is not in dBm. My question dupposed to be the difference between RxQual Sub and RxQual Sub(%).
    I still dont understand the difference between SQI and RxQual. they both based on BER, both measured quality. Can you help me more about this?
    May i have your e-mail add?
    Thank you

    30th December 2005 at 13:09 #33006
    Erik
    Guest

    Sure: erik.lallemand@ifrance.com
    But I don’t garantee that I can answer all questions :o) I am not (yet?) an expert.

    Anyway, for RxQual, I can give a few more details here; It’s strongly related to the channel coding of the messages sent over the air interface. Some extra bits are added to the messages in order to:
    1) detect errors
    2) correct errors

    So, if you have 1 bit error in 1 frame, no problem. The error will be corrected thanks to the redundancy introduced by the channel coding. The person on the other side of the communication will not hear anything strange as he/she will receive the complete frame with no error.
    Some other techniques are used in order to make the channel more failproof, like interleaving which spreads data over different frames (because heavy corruption of bits generally happen in a bursty way, not as a continuous process). So you can tolerate some bit errors and still have a perfect communication quality.

    But when you lose a complete frame, that’s another story. Some information is lost and you cannot recreate the full frame. This will impact the quality of the voice communication. So for voice quality, Frame Erasure Rate (FER) is more relevant than RxQual.

    18th January 2006 at 01:12 #33007
    Michael
    Guest

    Good day! is there a free calculator that can calculate the number of lines despite of having a BHT value above 180?

    18th January 2006 at 01:31 #33008
    Michael
    Guest

    Good day!May I ask for help? CAn you please share to me the erlang B formula? We needed it in our communication systems Design project. here’s my email ad: roysky_001@yahoo.com
    Thanks!

    18th January 2006 at 06:57 #33009
    Cerebrum
    Guest

    Ex(A) = (A · Ex−1(A))/(x + A · Ex−1(A))
    , E0(A) = 1
    This recursion formula is exact, and even for large values of (n,A)
    there are no round off errors. It is the basic formula for numerous tables of the Erlang B formula.
    You must involve a cycle to evaluate needed number of servers(lines). The index in the bottom of E is the number of channels. It asumes that if there is no available cirquits, hence, all traffic will be lost.
    If you want to contact me, my email is:valentin.georgiev@gmail.com

    23rd January 2006 at 09:58 #33010
    Timothy
    Guest

    Greetings:

    How does one apply the Erlang B formula when Half Rate is used?

    23rd January 2006 at 12:48 #33011
    Boko
    Guest

    Just double the channels. But check the Threshold for HR activation.

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