Research On Device-to-device(D2D) Video Transmission Technology Based On Network Coding

In recent years,with the popularity of mobile devices and the rise of video services,there has been an increasing demand for video viewing on mobile devices.Frequent device connections and increasing network scale have increased the burden on base stations,the traditional cellular network has been unable to meet the needs of the next generation of mobile communications.In the process of video transmission,how to improve the reliability of transmission,reduce the burden of the base station and satisfy the demand for video viewing has become a hot issue in the next generation of communication research.D2D(Device-to-Device)technology,as one of the core technologies in 5G(5th-generation)communication,provides new application scenarios for video transmission.In addition,network coding technology can effectively improve network throughput and transmission reliability.The integration of D2 D technology and network coding technology can improve the overall performance of the network,especially when it is oriented to video services,it can obtain stable and clear video streams.In the traditional cellular network,video sharing between multiple users will occupy high transmission resources.Unreliable transmissions will cause the loss of video frames,thus affecting the user's viewing experience.To solve this problem,this thesis proposes a video distribution scheme based on network coding in D2 D environment.In this scheme,network coding technology is applied to H.264 video transmission.Different encoding methods are adopted according to the importance of video frames in the video stream,which provides additional protection for key information in the video stream,thereby improving the probability of successful video decoding.In addition,a probability-based mathematical analysis model was established in D2 D transmission environment to analyze the effects of packet loss rate and video frame length on the successful decoding rate.Under the simulation environment setting,the simulation results show that the decoding rate of this scheme is higher than that of the traditional scheme.In the process of video transmission,packet loss is inevitable.The traditional retransmission scheme based on replication occupies the bandwidth of the base station and increases the transmission pressure of the base station.How to help mobile devices recover lost packets while reducing the burden of base stations is a problem to be solved.To solve this problem,this thesis proposes proposes a retransmission mechanism based on network coding,using D2 D technology to assist the base station in retransmission.In order to avoid D2 D device transmission conflict,a device selection algorithm is proposed to select the transmission device which can bring the maximum transmission gain as the sending end in each transmission.An undirected graph based on immediate decodable coding is constructed to represent the coding relationship between data packets,so that as many data packets as possible can participate in generating coded data packets.The simulation results show that compared with the traditional scheme,the proposed scheme can reduce the retransmission times and improve the retransmission efficiency.Based on the above research results,this thesis designs a D2 D video transmission system based on network coding with the software development platform Android Studio,which realizes the effective combination of video transmission technology and network coding technology in WifiDirect environment.Through the function tests and performance tests of the system,it is verified that the system designed in this thesis can realize the basic functions.The system can improve the overall performance of video transmission and enhance the user's video viewing experience.