Research On Video Communication Technologies Oriented To D2D Networks

The contradiction between the ever-increasing mobile data traffic and limited spectrum resources has given birth to device-to-device communications(D2D)technology,which improves the spatial utilization of the spectrum.Direct communication between adjacent devices without the involvement of base stations(BS)can significantly reduce the communication distance.Thus,it would increase the data transmission rate,spectrum efficiency,and spatial spectrum utilization,as well as reduce the transmission delay,transmission power consumption,and the traffic load of BS.Therefore,D2 D communication is considered as one of the key enabling technologies in the beyond fifth-generation(B5G)mobile communication system.Existing research has found that D2 D communication technology is particularly suitable for highspeed,low-latency video communication scenarios.However,to achieve efficient video transmission in D2 D networks,three key issues still need to be solved: 1)The users’ needs are diverse,terminal devices are various,and wireless channels are changeable.Video encoding is required to be scalable,flexible,and simple.2)The contradiction between the extremely high demand for network resources in the transmission of massive video data and the diversity,dispersion,and low utilization of network resources requires comprehensive coordination and scheduling.3)The random access and disconnection of user devices,as well as the mobility and selfishness of users,make it difficult to implement D2 D collaboration.A collaboration mechanism that combines fairness and incentives is needed to promote the collaborations.In response to the above three issues,this dissertation studies the coding issue,transmission scheduling issue,and content sharing issue in D2 D video communications.The main work and innovations of this dissertation can be summarized as follows:1)A video coding scheme for D2 D communications is studied in this dissertation.Aiming at the instability of wireless channels and the diversity and heterogeneity of D2 D networks,a flexiblescalable video coding scheme is proposed by combining the technical advantages of scalable video coding and multi-description video coding.First,the characteristics of D2 D communication are studied by constructing a D2 D communication system model.Accordingly,a flexible-scalable video coding(F-SVC)scheme is proposed by weakening the inter-layer dependency of scalable video coding and reducing the coding redundancy of multiple description video coding.Finally,the flexibility and scalability of video streaming can be adapted to video transmission in collaborative D2 D networks.2)A video stream transmission scheduling strategy in the D2 D networks is proposed in this dissertation.Aiming at the contradiction between the extremely high demand for network resources for mass video transmission and the low utilization rate of D2 D network resources,a video stream scheduling strategy is proposed.Firstly,based on the structural characteristics of the F-SVC video stream,the distribution prediction algorithm of video slices is designed through the global observation and perception of network status.Secondly,global scheduling of video stream transmission can be realized based on the proposed video slice distribution prediction algorithm.Finally,based on the goodput model of wireless channels,a link selection strategy in D2 D collaborations is proposed to improve the utilization efficiency of the spectrum.3)A collaborative D2 D video content sharing mechanism is constructed.In the view of insufficient motivation of users to share video content and the difficulty of D2 D collaboration between multi-user devices,based on a coalitional game and social attributes between user devices,a social-content-aware collaborative D2 D video content sharing mechanism is constructed.Firstly,using the method of coalitional game,by introducing social and content information,a mutually beneficial collaboration strategy is constructed while motivating users to participate in collaborations.Finally,combined with the characteristics of the code stream structure of F-SVC,a video transmission strategy in the D2 D collaborative content sharing network is designed to ensure the quality of experience(Qo E)of users.In summary,this dissertation studies video communication issues in D2 D networks from three aspects: video encoding,transmission scheduling,and content sharing,and aims to provide a comprehensive solution for D2 D video communications.First of all,the proposed coding scheme can endow the video stream with flexibility and scalability and is thus suitable for distributed storage,sharing,and transmission in D2 D networks.Furthermore,the proposed video transmission scheduling strategy can improve the resource utilization of terminal devices and make the distribution of video content easier to carry out D2 D collaborations.Finally,the proposed video content sharing mechanism can enable fair and incentive D2 D collaborations to be carried out efficiently,thereby improving the system throughput and video quality significantly.