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Engset Calculation This article is one of a group being considered for deletion in accordance with Wikipedia's deletion policy. Please see the policy discussion page of the votes for deletion list for details. This request is being discussed to form a consensus whether this is, or could be, an article appropriate for Wikipedia. If you feel deletion is not justified by Wikipedia deletion policy you may vote against its deletion. Please do not remove this notice or blank this article while the question is being considered. However, you are welcome to continue editing this article, especially if you can address the concerns of those who believe the article should be deleted. Should you do so, please remark on the policy discussion page regarding its improvement. The Engset calculation was named after its developer, T. O. Engset, who developed it to determine the probability of congestion occurring within a telecommunications network. The level of congestion can be used to determine a network's performance as it directly relates to grade of service. The formula requires that the user knows the expected peak traffic, the number of sources (callers) and the number of circuits in the network. Engset's equation is similar to the Erlang-B formula; however it contains one major difference: Erlang's equation assumes an infinite source of calls and Engset specifies a finite number of calls 1. Engset's formula requires recursion to solve. To determine the probability of congestion, the user must first determine an initial estimate. This initial estimate is substituted into the equation and the equation then is solved. The answer to this initial calculation is then substituted back into the equation, resulting in a new answer which is again substituted. This iterative process continues until the equation converges to the correct answer 2. Engset's equation is as follows 1: -
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where - A = offered erlangs from all sources
- S = number of sources
- N = number of circuits
- P(b) = probability of blocking or congestion
References 1 Parkinson R., Traffic Engineering Techniques in Telecommunications, Infotel Systems Inc http://www.tarrani.net/mike/docs/TrafficEngineering.pdf. Last accessed 13 February 2005 2 ITU-T Study Group 2, Teletraffic Engineering Handbook http://www.com.dtu.dk/teletraffic/handbook/telenook.pdf. Last accessed 13 February 2005
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