| As mobile communication enters the 5G era,video transmission has become an important part of data transmission.And it has become common to use mobile devices to watch videos,but this also puts higher requirements on communication services.In remote areas,it is difficult to provide communication services through terrestrial networks due to high construction costs.In addition,for special scenarios such as highspeed trains and airplanes,terrestrial wireless communication networks provide poor quality of service.The use of satellite for video services can solve the problems of limited coverage of terrestrial networks,poor disaster/destruction resistance,difficulty in coping with special terrain and unexpected situations.However,satellite communication systems also suffer from limited energy resources,limited frequency and time resources,unstable subsatellite uplinks and variable channel states,all of which can affect the transmission of video data.In view of this,this dissertation incorporates the Scalable Video Coding(SVC)technology into video transmission in satellite communication system and conducts a study on video transmission modeling and optimization,with the goal of improving the quality of video received by users and improving the quality of experience of users.The main research contents of this dissertation is summarized as follows:1.Satellite-to-ground downlink multi-user SVC video data transmission.In this dissertation,we study the optimization problem of multiuser SVC video data downlink transmission with access satellite relay,and consider the subcarrier resource constraint for satellites using Orthogonal Frequency Division Multiple Access(OFDMA)technology under the constrained total satellite power.And a joint optimization problem is proposed to solve the dynamic subcarrier resource allocation and SVC video layer selection problems in the subsatellite video transmission.Also considering the fairness among multiple users,the optimization objective is defined as the average of the logarithmic sum of the received video quality of all users.To solve this problem,this dissertation presents an algorithm for subcarrier resource allocation and video layer selection based on Lyapunov optimization theory and block coordinate descent method.Finally,it is experimentally demonstrated that this algorithm can effectively improve the received video quality of all users and reduce the interruption rate of video playback compared to the comparison algorithm.2.SVC video transmission in satellite communication system with video serversatellite-user trinity.Firstly,a satellite communication system video SVC transmission system model is constructed by combining the satellite and SVC video server and terminal equipment,and the video layer selection and resource allocation are decided independently by the communication satellite.The constrained multi-user transmission video quality maximization problem model is established by considering the constraints of satellite energy constraint,time resource constraint,satellite uplink-downlink transmission rate constraint and user-side video playback rate constraint.The optimization objective is defined as the average form of the sum of the Mean Opinion Score(MOS)corresponding to the video quality received by all users.To solve the proposed joint optimization problem,this dissertation uses Lyapunov stochastic optimization theory to decompose the original problem into three independent subproblems:satellite power allocation,SVC video layer selection and time resource allocation,and gives the solution strategies separately,which are then summarized as an algorithm used to optimize video transmission.Finally,the experimental results show that the proposed algorithms in this dissertation outperform the comparison algorithms in terms of improving the transmitted video quality,reducing the interruption rate and improving the total system throughput,which greatly improves the user experience. |
