Energy-efficient transmission for multimedia streams in last-hop wireless internet

Multimedia applications have unique characteristics that can be leveraged to design energy-efficient loss recovery mechanisms. Given their loss tolerance and strict timing requirements, various frame dropping policies can be used to affect both application performance and energy consumption. However, the effects on energy consumption of such frame dropping policies depends on not only high-layer effects, but also the MAC layer underlying them. Therefore, we first present an analysis of an energy-efficient MAC-layer protocol, called Fast Transmit MAC Protocol (FTMP). We then explore three frame dropping policies: proactive, reactive, and opportunistic. We present the EELR (energy-efficient loss recovery) protocol, which uniquely combines all three frame dropping policies to provide both high energy efficiency and high application performance. EELR is implemented in a real system on top of an energysaving MAC layer that exposes information about transmission costs to the transport layer for use in frame dropping decisions. Through analysis and real-world experiments, we show that the combination of an energy-efficient MAC layer with a transport protocol using all three frame-drop policies outperforms any other combination.