Proxy-based reference picture selection for real-time video transmission over mobile networks

We propose a framework for error robust real-time video transmission over wireless networks. In our approach, we cope with packet loss on the downlink by retransmitting lost packets from the base station (BS) 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 between the BS and the receiver. We deal with transmission errors on the uplink by sending acknowledgements and predicting the next frame from the most recent frame that has been positively acknowledged by the BS. We show that these two separate approaches for uplink and downlink nicely fit together. We compare our approach to state-of-the art error resilience approaches that employ random intra update of macroblocks and FEC across packets for error resilience. At the same bit rate and packet loss rate we observe improvements of up to 4.5 dB for our scheme.