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Unformatted text preview: + 1 = 0:5 If now the capacity is increased to 2 (= m), then the call blocking probability reduces to E 1 2 = 0:2. Note that ErlangB formula has nonlinear property. For example if offered load is 2 erl, and the
capacity is 2 channels, then the call blocking probability is E 2 2 = 0:4 which is smaller than when 1 erl
load was offered to link capacity of 1 channels (see above). CS 522, v 0.94, d.medhi, W’99 20 Example # 5:
This example shows how increase in call holding time impacts blocking.
Suppose that the average call arrival rate is 100 calls/hour, and the call holding time is 3 min, then the offered load is 5 erl. If the link capacity is 10, then call blocking probability is E 5 : 10 = 0 018 : Now suppose that the average call duration time increases (somehow) to 30 minutes; then the offered
load is 50 erl; Thus, the call blocking probability increases to E 50 10 = 0:8. Note that in this example,
the average call arrival rate did NOT increase at all. This show that the c...
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 Fall '08
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 Computer Networks

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