System throughput maximization subject to delay and time fairness constraints in 802.11 WLANs

It is difficult to achieve a trade off between system throughput fairness and channel access time fairness in 802.11 wireless local area networks (WLANs). The reason is that, under the multiple rate wireless protocol, a lower bit rate host penalizes hosts that use a higher bit rate with throughput fairness. In this paper, we propose a contention-based MAC (media access control) protocol for data communications in WLANs that achieves access time near-fairness and maximizes the aggregate throughput with simultaneous delay bound. Our suggested parameter values would help manufacturers and carriers of protocol configurations improve system throughput. This approach utilizes initial contention windows, packet size, and multiple back-to-back packets as decision variables. To evaluate our approach, we use an extended analytical model, which has been shown to be a non-linear dynamic integer problem. However, the experiment results show that a packet´s size and initial contention windows form a simple unimodal distribution to achieve access time near-fairness, which tends to maximize the packet´s size and increase the initial contention windows. Thus, we use a simple binary search to determine the composition of the initial contention windows, packet size, and multiple back-to-back packets. The system throughput increases as the number of packets in a block increases, but the delay also monotonically increases. We therefore consider the delay bound in order to limit the number of packets in a block. To evaluate our model, we use NS2 as a simulation tool. The results show that our model is accurate and that system throughput is maximized, subject to delay and time fairness.