Adaptive access mechanism with delta estimation algorithm of traffic loads for supporting weighted priority in IEEE 802.11e WLANs

Focusing on weighted throughput fairness that nodes get throughput proportions according to priority levels in IEEE 802.11e WLANs, we propose an adaptive and full-distributed access mechanism with delta estimation algorithm of traffic loads. We deduce a linear adjustment rule of Contention Window (CW) about traffic loads, which connects parameters of access mechanism with dynamic network conditions. To support weighted priority levels (WPLs) of throughput proportions, we introduce a priority index to restrict number of successful data transmission of nodes with different priority levels for accurate calculation of channel status information. And then, we give a delta estimation algorithm of traffic loads, which can reduce fluctuations of estimated results around true values. By setting different thresholds corresponding to the WPLs, each node can obtain suitable sizes of CW for better aggregated throughput even as the variations of traffic loads in networks. The selected sizes of CW determine the attempt probability of channel access, which guarantees the weighted fairness of throughput proportions corresponding to WPLs. The simulation results confirm the validity and good scalability of the proposed access mechanism with different ratios of node number between multiple priority levels.