Transport level performance-energy trade-off in wireless networks and consequences on the system-level architecture and design paradigm

Low power consumption is imperative to enable the deployment of broadband wireless connectivity in portable devices such as PDA or smart telephones. Next to low power circuit and architecture design, system-level power management is revealed to be a key technology for low power consumption. Recently, "lazy scheduling" has been proposed for system level power reduction. It has been shown to be very effective and complementary to more traditional shutdown based approaches. So far, analysis has been carried out from the viewpoint of medium access control (MAC) and data link control (DLC) layers. Yet, effective power management in radio communication requires consideration of end-to-end cross-layer interactions. In this paper, we analyze the implication of "lazy scheduling" from the transport layer perspective. It is shown that a key trade-off between queuing delay and physical layer energy drives the global trade-off between user throughput and system power. Conditions under which "lazy scheduling" is efficient are established and important conclusions on effective system-level architecture and cross-layer power management are drawn.