Energy efficient design of portable wireless systems

Portable wireless systems require long battery lifetime while still delivering high performance. The major contribution of this work is combining new power management (PM) and power control (PC) algorithms to trade o performance for power consumption at the system level in portable de-vices. First we present the formulation for the solution of the PM policy optimization based on renewal theory. Next we present the formulation for power control (PC) of the wire-less link that enables us to obtain further energy savings when the system is active. Finally, we discuss the measure-ments obtained for a set of PM and PC algorithms imple-mented for the WLAN card on a laptop. The PM policy we developed based on our renewal model consumes three times less power as compared to the default PM policy for the WLAN card with still high performance. Power control saves additional 53 % in energy at same bit error rate. With both power control and power management algorithms in place, we observe on average a factor of six in power sav-ings. 1