A Study Of Video Multicast Technology Based On D2D Communication

Due to the lack of radio spectrum resources,the explosion of multimedia services and the requirements of large bandwidth,low latency have brought a huge challenge to the existing wireless communication systems.It is crucial to research efficient video transmission schemes.Device-to-Device(D2D)cooperative multicast technology has huge potential to improve the utilization ratio of wireless resources and reduce the energy consumptions of the systems.Most of the existing video transmission schemes based on D2 D technology are aiming at improving the network throughput,spectrum efficiency and energy efficiency.These schemes pay no attention to the transmission contents.In practical applications,increase the transmission rate blindly,repeated and invalid frames are transmitted in the D2 D phase.To solve this problem,a mechanism which rank this video frames firstly,and then multicast them based on D2 D communication is proposed.In this thesis,according to the characteristics of video coding structure and user requirements,the priority of the retransmission video frames are set: the video frames which decode earlier and have larger userrequirements are set higher priority and vice versa.It ensures that users can get more efficient decoding information in limited time-frequency resources.Further,based on the different spectrum access methods,the problems of resource allocation and relay selection are analyzed.In overlay mode,an optimal relay selection and group partition strategy based on channel quality indication(CQI)matrix is proposed.When the network load is high,underlay mode is the more reasonable choice.In underlay mode,the problems of channel allocation,relay selection and group partition are jointly considered.Firstly,the optimal relay selection and group partition result is obtained by the traversal algorithm.Next,a sub-optimal heuristic algorithm is proposed from the users' point of view.The simulation results show that the proposed algorithm can transmit more effective video frames and improve the video resolution in the overlay mode.At the same time,users' fairness is guaranteed.In underlay mode,the heuristic algorithm proposed in this thesis not only reduces the complexity greatly,the deviation from the optimal algorithm is in the range of acceptable.