RESIDUAL SIGNALS MODELING FOR LAYERED IMAGE/VIDEO SOFTCAST WITH HYBRID DIGITAL-ANALOG TRANSMISSION

Recently, the SoftCast scheme has shown great potential for robust image/video communication in wireless scenarios, where the channel quality may fluctuate drastically and unpredictably. However, the analog-like transmission in SoftCast is not always efficient in terms of power usage, compared with digital approaches. In this paper, we propose a layered image/video SoftCast scheme, in which a coarse version of the image is transmitted by a base layer in digital way, while the residual details are delivered by an enhancement layer in pseudo-analog way. In order to achieve optimal overall transmission performance, this paper studies the problem of optimal bit rate selection for the base layer, by building a rate-residual model based on the relationship between the base layer bit rate and the residual signal spectrum. Experimental results show that the proposed scheme can improve the performance of original scheme remarkably, while still preserving the smooth quality degradation characteristic of SoftCast.