Application-driven power management for mobile communication

In mobile computing, power is a limited resource. Like other devices, commu nication devices need to be properly managed to conserve energy. In this pa per, we present the design and implementation of an innovative transport le vel protocol capable of significantly reducing the power usage of the commu nication device. The protocol achieves power savings by selectively choosin g short periods of time to suspend communications and shut down the communi cation device. It manages the important task of queuing data for future del ivery during periods of communication suspension, and decides when to resta rt communication. We also address the tradeoff between reducing power consu mption and reducing delay for incoming data. We present results from experi ments using our implementation of the protocol. These experiments measure t he energy consumption for three simulated communication patterns as well as three trace-based communication patterns and compare the effects of differ ent suspension strategies. Our results show up to 83% savings in the energy consumed by the communication. For a high-end laptop, this can translate t o 6-9% savings in the energy consumed by the entire mobile computer. This c an represent savings of up to 40% for current hand-held PCs. The resulting delay introduced is small (0.4-3.1 s depending on the power management leve l).