Department of Electrical and Electronic Engineering, Universiti Teknologi PETRONAS, Seri Iskandar, Perak, Malaysia.
Center for Cyber Security, Faculty of Information Science and Technology, Universiti Kebangsaan Malaysia, Bangi, Malaysia.
PLoS One. 2020 Aug 26;15(8):e0238073. doi: 10.1371/journal.pone.0238073. eCollection 2020.
Transmission opportunity (TXOP) is a key factor to enable efficient channel bandwidth utilization over wireless campus networks (WCN) for interactive multimedia (IMM) applications. It facilitates in resource allocation for the similar categories of multiple packets transmission until the allocated time is expired. The static TXOP limits are defined for various categories of IMM traffics in the IEEE802.11e standard. Due to the variation of traffic load in WCN, the static TXOP limits are not sufficient enough to guarantee the quality of service (QoS) for IMM traffic flows. In order to address this issue, several existing works allocate the TXOP limits dynamically to ensure QoS for IMM traffics based on the current associated queue size and pre-setting threshold values. However, existing works do not take into account all the medium access control (MAC) overheads while estimating the current queue size which in turn is required for dynamic TXOP limits allocation. Hence, not considering MAC overhead appropriately results in inaccurate queue size estimation, thereby leading to inappropriate allocation of dynamic TXOP limits. In this article, an enhanced dynamic TXOP (EDTXOP) scheme is proposed that takes into account all the MAC overheads while estimating current queue size, thereby allocating appropriate dynamic TXOP limits within the pre-setting threshold values. In addition, the article presents an analytical estimation of the EDTXOP scheme to compute the dynamic TXOP limits for the current high priority traffic queues. Simulation results were carried out by varying traffic load in terms of packet size and packet arrival rate. The results show that the proposed EDTXOP scheme achieves the overall performance gains in the range of 4.41%-8.16%, 8.72%-11.15%, 14.43%-32% and 26.21%-50.85% for throughput, PDR, average ETE delay and average jitter, respectively when compared to the existing work. Hence, offering a better TXOP limit allocation solution than the rest.
传输机会 (TXOP) 是实现无线校园网络 (WCN) 中交互式多媒体 (IMM) 应用高效信道带宽利用的关键因素。它为相似类别的多个数据包传输进行资源分配，直到分配的时间到期。IEEE802.11e 标准为各种类别的 IMM 流量定义了静态 TXOP 限制。由于 WCN 中的流量负载变化，静态 TXOP 限制不足以保证 IMM 流量流的服务质量 (QoS)。为了解决这个问题，一些现有工作根据当前关联队列大小和预设阈值动态分配 TXOP 限制，以确保 IMM 流量的 QoS。然而，现有工作在估计当前队列大小时没有考虑所有介质访问控制 (MAC) 开销，而这是动态 TXOP 限制分配所必需的。因此，不适当考虑 MAC 开销会导致不准确的队列大小估计，从而导致动态 TXOP 限制的不适当分配。本文提出了一种增强的动态 TXOP (EDTXOP) 方案，该方案在估计当前队列大小时考虑了所有 MAC 开销，从而在预设阈值内分配适当的动态 TXOP 限制。此外，本文还提出了一种 EDTXOP 方案的分析估计，以计算当前高优先级流量队列的动态 TXOP 限制。通过改变数据包大小和数据包到达率来改变流量负载，进行了仿真。结果表明，与现有工作相比，所提出的 EDTXOP 方案在吞吐量、PDR、平均 ETE 延迟和平均抖动方面分别实现了 4.41%-8.16%、8.72%-11.15%、14.43%-32%和 26.21%-50.85%的整体性能提升。因此，它提供了比其他方案更好的 TXOP 限制分配解决方案。
