The Scalable Video Multicast Technology Based On NOMA

With the growing volume size of high definition video and the booming of video applications,the mobile video traffic has an increasing proportion in wireless data transmission.Despite the rapid development of mobile communication technologies,when faced with the high bandwidth consumption and low latency transmission requirements of video data,the wireless resources of existing 3G/4G systems are still limited compared with the increasing video traffic.Non-orthogonal multiple access(NOMA)technology,with its own nonorthogonal advantages,increases the number of user connections while improving spectrum efficiency,and thus becomes a candidate for the future 5G multiple access.In the process of video transmission,the wireless multicast technology has received extensive attention due to its high spectrum efficiency.However,because of the bottleneck of multicast,the application of multicast is greatly limited.The scalable video multicast divides the multimedia video stream into a base layer and several enhancement layers and then transmits them separately.Therefore,the difference between the user terminals and the channel can be satisfied,and thus improving the system performance.At present,the research on the scalable video multicast mainly focuses on the network based on the orthogonal access technology.In order to avoid interference,the orthogonal resource of time and frequency is used for different layers of the scalable video streaming.However,the above method still does not make full use of the spectrum resources.Besides,the spectrum efficiency which is used for the transmission of the basic video layer is still limited by the worst channel link among users.In this paper,we propose a flexible scalable video transmission strategy based on the non-orthogonal multiple-access for the efficient transmission of scalable multicast under the consideration of the advantages of the above non-orthogonal multiple access techniques and scalable video coding.This strategy considers the difference of the channels in the multicast group and improves the system performance by flexibly selecting multiple video layers of scalable video in non-orthogonal mode.Firstly,the framework of scalable multicast system based on the non-orthogonal multiple access is proposed.Meanwhile,the optimization problem of maximizing users' video quality through power allocation strategy is studied,and it is proved that the optimization problem is a NP-hard problem.Secondly,a dynamic programming algorithm with low algorithm complexity is proposed to solve the above optimization problem,and an optimal solution is obtained in polynomial time by skillfully setting up auxiliary functions and recursive formulas.Further,an improved dynamic programming algorithm with lower algorithm complexity is proposed,and the complexity of the above algorithms is analyzed respectively.Finally,the simulation results show that the proposed scalable video multicast transmission strategy based on nonorthogonal multiple-access can adapt to different channel conditions of the multicast group compared to the traditional orthogonal framework and both quantity and fairness have been effectively improved.