Proxy-based reference picture selection for error resilient conversational video in mobile networks

We propose a frame dependency management strategy for error robust transmission of conversational video in mobile networks. We consider an end-to-end video transmission scenario that involves both a wireless uplink as well as a wireless downlink plus some intermediate wireline network transmission. We also investigate the special cases of an end-to-end scenario where only a wireless uplink or a wireless downlink is present. We cope with packet loss on the downlink by retransmitting lost packets from the base station to the receiver for error recovery. Retransmissions are enabled by using fixed-distance reference picture selection during encoding with a prediction distance that corresponds to the round-trip time of the downlink combined with accelerated decoding. We deal with transmission errors on the uplink by sending acknowledgments and predicting the next frame to encode from those slices that have been correctly received by the base station. We show that these two separate approaches for uplink and downlink efficiently complement one another and the resulting end-to-end scheme is characterized by very low computational complexity. We compare our scheme to several state-of-the-art error resiliency approaches and report significant improvements.