Energy-minimized wireless video transmissions via sharing of retransmission limits

In wireless video streaming, a video frame is usually large in data load and is truncated into multiple transport packets for reliable transmissions. These transport packets should be transmitted successfully before a deadline for frame decoding. High bitrate and high power transmission schemes are often deployed to ensure reliable transmissions. Such a method however incurs substantial energy consumption. Unlike existing methods which assign the retransmission limit independently to each transport packet, we share the retransmission opportunity among transport packets of a video frame, and jointly optimize it with transmission rate and power such that the video frame delivery is energy efficient. Contrary to the common intuition that avoids packet loss and retransmission to preserve energy, our approach yields lower energy consumption by judiciously inducing loss and retransmission of the transport packets, without violating the deadline and reliability constraint. Numerical results reveal that the joint optimization improves energy efficiency in wireless video transmissions. The improvement is even more significant when the allocated transmission time is limited or the reliability constraint is tightened.