Network Transmission Optimization For VR Video Based On Fountain Codes

360 virtual reality(VR)video is one of the popular VR appli cations.Because VR video transmission needs giant bandwidth res ources to guarantee users' quality of experience.Different from tra ditional video,VR video has the characteristics of Field of view(FOV),user can only see part of the 360 spherical video when w atch VR video,the part of area is called FOV.Apparently,the us ers' watching experience can be directly improved by enhancing th e video quality of FOV.Fountain codes are kind of network technology suitable for la rge-volume data transmission.Expanding window fountain(EWF)codes introduce unequal error protection into fountain codes throug h the idea of "windowing".For data with different importance lev els,EWF code can protect data with high importance level during network transmission,and enhancing their reliability.Plenty of schemes have been proposed to optimize the transm ission of VR video.Most of these schemes aimed to reduce the d ata size of VR video source,thereby reducing the bandwidth requi rement of VR video transmission.In our proposed scheme,expand ing window fountain(EWF)codes is introduced to protect the Fie Id of View(FOV)of VR video by sacrificing the quality of non-FOV.Under the same bandwidth conditions,this UEP method can improve the video quality of FOVs where users actually watching.By adjusting the window selection probability of EWF codes,we discuss the optimal degree of protection for the FOV.Moreover,to better evaluate the quality of VR video,we define a new metri c called VP-PSNR to measure the quality of VR video.According to the simulation results,under the packet loss network transmissi on condition,our UEP scheme can effectively improve the quality of VR video compared with traditional equal error protection(EEP)scheme.