Grade of Service - Erlang's Lost Call Assumptions

Erlang's Lost Call Assumptions

To calculate the Grade of Service of a specified group of circuits or routes, Agner Krarup Erlang used a set of assumptions that relied on the network losing calls when all circuits in a group were busy. These assumptions are:

  • All traffic through the network is pure-chance traffic, i.e. all call arrivals and terminations are independent random events
  • There is statistical equilibrium, i.e., the average number of calls does not change
  • Full availability of the network, i.e., every outlet from a switch is accessible from every inlet
  • Any call that encounters congestion is immediately lost.

From these assumptions Erlang developed the Erlang-B formula which describes the probability of congestion in a circuit group. The probability of congestion gives the Grade of Service experienced.

Read more about this topic:  Grade Of Service

Famous quotes containing the words lost, call and/or assumptions:

    We have to divide mother love with our brothers and sisters. Our parents can help us cope with the loss of our dream of absolute love. But they cannot make us believe that we haven’t lost it.
    Judith Viorst (20th century)

    The members of a body-politic call it “the state” when it is passive, “the sovereign” when it is active, and a “power” when they compare it with others of its kind. Collectively they use the title “people,” and they refer to one another individually as “citizens” when speaking of their participation in the authority of the sovereign, and as “subjects” when speaking of their subordination to the laws of the state.
    Jean-Jacques Rousseau (1712–1778)

    Assumptions of male superiority are as widespread and deep rooted and every bit as crippling to the woman as the assumptions of white supremacy are to the Negro.... this is no more a man’s world than it is a white world.
    Student Non-Violent Coordinating Committee, African American civil rights organization. SNCC Position Paper (Women in the Movement)