Throughput-Based Mapping Algorithm for Video Streaming over IEEE 802.11e WLAN

IEEE 802.11e utilizes the Enhanced Distributed Channel Access (EDCA) protocol to provide quality of service (QoS) support over WLANs. However, under EDCA, all video data are allocated to the same access category (AC) queue, irrespective of their coding importance. Consequently, the quality of the transmitted video may be severely degraded under heavy traffic load conditions. The literature contains several queue mapping mechanisms based on the settings of the AC queues, such as contention window size, for improving the video transmission quality over IEEE 802.11e WLANs. However, these mechanisms fail to consider the effect of the dequeuing time on the video delivery performance. Accordingly, the present study proposes a new queue mapping algorithm, designated as the throughput-based mapping algorithm (TMA), for improving the video transmission quality and reducing the video delay by dynamically allocating the video data packets to different AC queues based on their length and throughput such that the probability of the dequeuing time being reduced is increased. In implementing the proposed approach, the throughputs of the AC queues are analyzed using two Markov chain models. The simulation results show that TMA outperforms previously proposed static and dynamic queue mapping schemes in terms of a reduced AC queue length, an improved PSNR (peak signal-to-noise ratio), and a shorter transmission delay.