Mechanism for ATM access networks

This paper presents an analytical model for request polling, which is part of many tree topology shared media ATM access network proposals. The upstream transmission of ATM cells is controlled by a centralised MAC controller in the head end. Physical layer functions demand a per-cell overhead, which can also be used to carry MAC (media access control) information. In order to give previously inactive stations a chance to transmit their MAC information, additional overhead must be spent, which reduces the upstream ATM cell transport capacity. An access network using only this additional overhead to carry MAC information, is modelled in this paper by analysing a D/sup [GI]//D/1 model with cyclic vacations. To compute the end-to-end delay distribution, the delay distribution obtained from the D/sup [GI]//D/1 analysis is convolved with the distribution seen in a clocked batch gate. Results indicate the optimum amount of transport capacity to spend for request polling to minimise the delay quantiles.