Research And Implementation Of QoE Enhanced Wireless Video Adaptive Transmission Control Algorithms

With the rapid development of communication technology,video stream has become the main source of Internet traffic in recent years.Video data transmission requires high network bandwidth.According to different transmission scenarios(such as live video),there are strict requirements for end-to-end transmission delay and delay jitter.The bottleneck of video transmission is the lack of bandwidth resources,so a single wireless access technology is limited by the limited bandwidth and cannot provide users with high-quality and high-definition video experience in real time.In addition,because the wireless network channel is easy to fluctuate under external interference,the key of wireless video transmission control technology is how to adjust video playback according to timevarying wireless network,so as to make full use of network resources without causing waste of network bandwidth and improve the quality of user experience.Therefore,how to dynamically select appropriate bitrate video clips to adapt to the complex and changeable network environment and improve user experience so that users can see as clear and fluent video as possible has become a challenging task.Aiming at the problem that single wireless access transmission technology cannot carry enough UHD video and that the dynamic changes of network make the existing algorithms unable to automatically adapt to the complex and changeable network,this thesis mainly studies the following three aspects:(1)To solve the problem that single access technology bandwidth cannot meet the transmission of UHD video,based on multi-terminal.A "super virtual terminal" is synergistically formed to realize the concurrent transmission technology of video streams in heterogeneous wireless networks.This technology uses scheduling algorithm of concurrent video streams,buffer overhead and packet invocation methods,as well as packet loss prevention and recovery methods to improve the performance of the system.The simulation results show that the concurrent transmission technology improves the system parameters such as delay,packet loss and bit error rate.It improves the performance of the system.(2)In view of the problem that the current wireless video transmission system cannot adjust the transmission rate adaptively to improve the experience,considering the length of the receiver buffer and the user experience Qo E,a video transmission control model based on Markov decision-making is established to form a Qo E-driven closed-loop feedback control system for video transmission,which can be adapted according to user experience.Finally,Q learning algorithm is applied to solve the decision model to obtain the optimal transmission rate strategy of user experience.The simulation results show that the adaptive control algorithm can significantly improve the quality of network service and user experience.(3)A video adaptive transmission control system based on Q-learning is implemented.Moreover,the video rate of the sender can be dynamically adjusted according to the network parameters in real time to avoid wasting the bandwidth resources,so that users can get the best video viewing experience under the current network conditions.The simulation results show that the system using the adaptive algorithm can dynamically adjust the video bit rate according to the network conditions,and the system stability and user experience have been significantly improved.