The effects of packet size distributions on output and delay processes of CSMA/CD

An unslotted model of the nonpersistent CSMA/CD protocol is considered, and the effect of different packet size distribution functions on the system performance is investigated. Under the assumption that packet sizes obey a general distribution function, an exact analysis of the packet output process on the CSMA/CD channel and the packet delay process at each homogeneous station is presented. Statistics analyzed are the following: (1) the Laplace-Stieltjes transform (LST) of the probability distribution function (PDF) of the packet interdeparture time, (2) the autocorrelation coefficient of the packet interdeparture time, (3) the LST of the PDF of the packet delay, and (4) the LST of the PDF of the waiting time. In addition, explicit expressions for the LSTs, averages and variances of the interdeparture time, packet delay, and waiting time distribution functions are given under the heavy-traffic assumption. In numerical results, typical packet size distribution functions are applied to the analytical result, and their effects on the autocorrelation coefficient of the interdeparture time as well as the averages and coefficients of variation of the interdeparture time, packet delay, and waiting time are examined.<
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