Physical- and link-layer modeling of packet-radio network performance

An analytic model that takes into account the properties of realistic link-layer mechanisms, such as the unreliable nature of acknowledgements, is presented. Attention is given to the mixed-packet capability of the model; the user may specify the distribution of packets having a particular combination of forward error correction and symbol rates. The resulting models cannot be solved analytically, so an algorithm for obtaining a numerical solution is presented. Results are presented for a variety of network parameters. A computer implementation of this model shows that failing to account for the nonideal behavior of acknowledgements overstates throughput by a factor of two, that allowing too many transmission attempts causes throughput to suffer, and that throughput is a strong function of the desired packet reliability and neighborhood size.<
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