Power Amplifier Characteristic-Aware Energy-Efficient Transmission Strategy ⋆

Abstract. The energy consumption in transmitting an information bit, i.e., energy-per-bit, has been known to decrease monotonically as the transmission time increases [1]. However, when considering the power amplifier (PA) characteristics, we learn that the energy-per-bit starts to increase as the transmission time becomes long over a certain threshold. This is caused by the fact that, in a wireless device, it is not the transmission power, which determines the energy consumed during transmissions, but the input power to the PA whose output power is used as the transmission power. Based on our new trade-off model between the energy-per-bit and transmission time, we revisit known energy-efficient scheduling algorithms. Finally, we evaluate the impact of the new tradeoff model and the performance of algorithms via simulations.

An Energy-efficient Protocol for Multimedia Streaming in a Mobile Environment

Pervasive services and smart environments are becoming more and more popular as an ever-increasing number of people enjoys these services typically by means of portable devices. These devices are battery-fed and, thus, energy efficiency is a critical factor for the deployment of pervasive services. In this paper we focus on multimedia streaming services for mobile users. Specifically, we consider a scenario where mobile users with Wi-Fi devices access the Internet to receive audio files from a remote streaming server. We propose a proxybased architecture and an energy-efficient streaming protocol that minimize the energy consumption of the Wi-Fi interface at the mobile device, while guaranteeing the real-time constraints of the audio streaming. The experimental analysis performed on a prototype implementation shows that our solution allows an energy saving ranging from 76%to 91%of the total consumption due to the network interface. Moreover, it also preserves a good user-level Quality of Service