SoftCast-based Wireless Video Transmission:Optimization Over Multiple Time Slots

In recent years,with the development of video conference,live video streaming and other applications of the wireless video,the scale and traffic of wireless video have grown at an unprecedented rate.How to transmit stable and high-quality wireless video has become a hot research topic.Traditional wireless video transmission scheme faces two major problems of poor scalability and poor robustness as the increase of many users' demands,which seriously affect the quality of the video received by users.While the scalable video coding scheme improves the scalability of the transmission to a certain extent,it still cannot realize that users obtain the video quality corresponding to the channel condition.To address this issue,researchers proposed a pseudo analog video transmission scheme SoftCast.Its system model consists of a series of linear transformations such as 3D-DCT,block energy allocation,linear least squares estimation,etc.,which can effectively improve the scalability and robustness of wireless video transmission.However,the received quality is not well improved as the fluctuations of the wireless channel as well as the lack of the information of the wireless channel.In this paper,firstly,we study the system model of SoftCast and verify its advantages compared with the traditional transmission scheme through several simulations.However,SoftCast can only improve the received quality by retransmitting data when there are multiple time slots.Therefore,in the case of multiple time slots,we keep the energy allocation of SoftCast,change the inherent retransmission scheme of SoftCast and perform joint decoding during multiple time slots at the receiver to optimize the overall transmission.Then,for the deficiencies of SoftCast,we study ParCast,which exploits the state information of the channels.ParCast sorts channels according to the quality and allocates energy based on one-to-one correspondence between the channels and the blocks,then transmits the data on the OFDM channel.Therefore,it performs better than SoftCast.In the case of multiple time slots,the optimal resource allocation scheme is proposed by exploiting the diversities of time to achieve high quality wireless video transmission.We study how to optimally allocate resource during each time slot to maximize the PSNR at the receiver.Simulations show that this transmission scheme can achieve better performance on both the PSNR and the visual quality of the received videos.