Dynamic, power-aware scheduling for mobile clients using a transparent proxy

Mobile computers consume significant amounts of energy when receiving large files. The wireless network interface card (WNIC) is the primary source of this energy consumption. One way to reduce the energy consumed is to transmit the packets to clients in a predictable fashion. Specifically, the packets can be sent in bursts to clients, who can then switch to a lower power sleep state between bursts. This technique is especially effective when the bandwidth of a stream is small. This paper investigates techniques for saving energy in a multiple-client scenario, where clients may be receiving either UDP or TCP data. Energy is saved by using a transparent proxy that is invisible to both clients and servers. The proxy implementation maintains separate connections to the client and server so that a large increase in transmission time is avoided. The proxy also buffers data and dynamically generates a global transmission schedule that includes all active clients. Results show that energy savings within 10-15% of optimal are common, with little packet loss.