Vehicular wireless network access controller parameter estimation

摘要

Two-rank integrated Wi-Fi and LTE wireless network can be used to provide Internet access to mobile vehicular users. Wi-Fi access controller and LTE router are processing traffic flow, which is delivered from connected wireless access points (AP). And in turn, the traffic flow from mobile vehicular clients goes towards the AP. Each of these nodes is processing incoming flow with a certain performance, and maximum network throughput directly depends on these nodes and amount of mobile clients. It depends on both the first rank and the second rank, and the maximum performance of such a network will be the maximum, but mutually minimal, performance of these two-rank systems. To evaluate necessary buffering amount we need to determine incoming flow, its intensity and characteristics to be able to provide for example client's SLA (Service Level Agreement) requirements. To answer these questions experimental measurements were made in field environment. Experimental measurements were carried out with one and two mobile vehicular clients. A possible mathematical model is offered by using queuing model P/M/1/K and also the evaluation of packet loss probability is carried out. The analysis of obtained experimental data shows that summary flow is self-similar. By evaluating flow intensity and the magnitude of Hurst parameter (H), certain recommendations developed, by which buffer memory amount, outgoing throughput, packet loss probability and system utilization can be evaluated. Depending on AP amount involved, the evaluation of concentrator's outgoing channel throughput is carried out experimentally and mathematically. For theoretical evaluation a “Machine repairman” model was used.