802.11 In The Network Video Streaming Queue Scheduling Methods Of Research

With the explosion development of Wireless Local Area Network technology, their applications has gradually extended to all areas of people’s daily work and life. Wireless Services, especially multimedia application, is also rising rapidly. Therefore, people pay more and more attention on how to provide QoS for different data transmission. Finally, the protocol of IEEE802.11e is proposed. There are four access categories in the MAC layer for different applications, and the ACs all have different media access priorities, so this mechanismcan can partly provide QoS for voice and video data transmission. But its performance is limited by the first-in-first-out (FIFO) characteristic of reserved access category queue.Nowadays, MPEG-4coding technique is one of the most widely used Hierarchical Coding techniques. Based on spatial and temporal coding, there are three types of video frames:I/P/B, with different importance. So cross layer design is introduced to improve the quality of service. Using the difference of data importance from application layer to assign the different access priorities in MAC layer, then protecting the important video data transmission and eventually to improve the overall quality of video has become the key research direction.In this paper, we first introduction the protocol of IEEE802.11e and MPEG coding technique, and analysis the drawback of QoS support of current wireless network. After that we introduce two video streaming queue scheduling algorithms, one is static mapping algorithm, the other is adaptive mapping algorithm. Then using the network simulator ns-2and the video quality evaluation tool set Evalvid to evaluate the performance of the three algorithms in different congestion levels and analysis their advantages and disadvantages. Finally, we proposed a novel probabilistic packet mapping algorithm called Piecewise mapping.The Piecewise mapping algorithm uses the idea of cross layer design. Depending on the congestion levels of AC_VI, the proposed algorithm can actively manage AC_VI by proposing four downward transition phases to decide the mapping probabilities among AC_VI and the lower-priority ACs. The four phases include zero transition phase in light congestion, full transition phase in heavy congestion, and two proportional transition phases in medium congestion between the low and high thresholds of the AC VI queue length. Our results show that the proposed Piecewise Mapping algorithm outperforms the best result of existing work Adaptive Mapping.Finally, we’ll analysis the parameters setting of the proposed algorithm. From which we find that the setting of thresholds, the maximum transition probabilities and the length and slope of the two proportional transition phases will have a serious influence on the performance of the our proposed algorithm. This paves the way of the similar study in related field in the future.