适用于无线视频传输的动态调度机制

对于无线网络传输实时高清视频时延高的问题,提出了一种增强型混合协调功能(EHCF)的动态调度机制。首先,利用截断和扩展信标间隔以适应视频数据的突发性;然后,根据站点数据缓存量大小来判断各站点传输需求,并由此划分在当前信标间隔中的优先级;其次,利用传输需求门限值和差值门限来评估高优先站点的传输需求权重;最后,根据评估结果为各站点分配信道资源。在基于H.264的视频传输仿真实验中,该机制以22 Mb/s的传输速度且网络站点个数相同时与传统的IEEE 802.11e中混合协调功能(HCF)相比,时延下降幅度最高为87.6%,最低为54.3%。仿真结果表明,EHCF机制在无线视频传输中能有效提高网络的实时性。

Dynamic scheduling mechanism for wireless video transmission

Focused on the issue that the wireless real-time transmission network of HD (High Definition) video has characteristics of long delay, a dynamic scheduling mechanism based on Enhanced Hybrid Coordination Function (EHCF) was proposed. In this mechanism, firstly, truncation and extension of beacon interval were used to adapt to the burst of the video data. Then, the transmission needs of each station were determined by its cache size of the video data, and accordingly, the priority of the station was defined. Next, the threshold of transmission needs and differences were applied to evaluate the weights of transmission needs of the high priority stations. Finally, the channel resource was allocated according to the assessment. A comparison with traditional Hybrid Coordination Function (HCF) was made according to H.264-based video transmission simulations with 22 Mb/s and same number of stations. The result shows that there is a significant improvement on delay, ranging from 54.3% to 87.6%. The theoretical analysis and simulation results show that the EHCF mechanism can effectively improve the delay of network in wireless video transmission.