Research On Recursive Distortion Estimation And Power Allocation For Hybrid Digital-analog Video Transmission

Wireless video transmission is becoming more and more important and popular in many applications,such as mobile TV,video surveillance and online education.This presents two major challenges to the conventional digital communication systems including “saturation effect” in digital video coding and “cliff effect” in digital channel coding.Recently,a Hybrid digital analog(HDA)video transmission scheme was proposed,which has advantages in avoiding “cliff effect”.However,most current HDA schemes assume perfect transmission of the digital signal,which is hardly the case in practice.Therefore,this paper mainly focus on the distortion problems of digital and analog signals in the HDA scheme,the main works and innovations are as follows:Firstly,we proposed a recursive distortion estimation model(RDE-HDA)for hybrid digital and analog video transmission.Based on this model,we can estimate the decoder-side distortion at the encoder under the given channel condition.In the proposed scheme,based on the influence the distortion of digital signal and analog signal for the quality of reconstructed video,we also consider the distortion due to the superposition processes in HDA system.In addition,assuming the digital signals suffer from a BER of p during transmission,we derive a closed-form expression of the video distortion by considering both transmission error in the digital signal and analog signal.Therefore,the RDE-HDA method does not require the digital part of the HDA output to be transmitted losslessly,making the HDA more practical for the actual wireless transmission system.The accuracy of our method is verified by simulation results.Secondly,an adaptive recursive distortion estimate for HDA-based transmission,abbreviated as ARDE-HDA.Based on the RDE-HDA scheme,we widely consider the adaptive power allocation between digital signals and analog signals,which can be used to optimize the quality of the received video.Besides,the power allocation of ARDE-HDA scheme is applied at the frame level,and compared with the RDE-HDA scheme,the transmission overhead of the power adjustment factors is negligible while the received video quality can be significantly improved.Experimental results show that compared with other advanced HDA schemes,the ARDE-HDA scheme proposed in this paper can get better reconstructed video quality under different channel conditions.