Energy Management in Mobile and Pervasive Computing Systems

Abstract

In the last decade, the explosion of the Internet, the development of wireless communication technologies, and the proliferation of portable devices has resulted in a revolutionary change in our information society starting the era of mobile computing. Currently, people use laptops, palmtops, smart-phones, and other handheld devices --extended with wireless technologies --to accomplish their tasks, access remote information, and communicate with other people anytime and anywhere. Projections show that in the next two years the number of mobile Internet connections will continue to grow by another 20-50 percent. With this trend, we can expect the total number of mobile Internet users to exceed that of the fixed-line Internet users in the very near future. The progress in hardware and software technologies in recent years has paved the way for the development of basic ingredients (handheld and wearable computers, wireless networks, devices for sensing and remote control, etc.) for making the new computing paradigm of pervasive computing (or ubiquitous computing) a reality. We are approaching the realization of environments that will be saturated with computing and communication and gracefully integrated with human users, thus extending the possibility to access information and/or communicate with other people. However, the potentialities of mobile and pervasive computing systems are still limited by a number of factors, among which energy-related issues are perhaps the most relevant ones. As portable devices are battery powered they have limited energetic resources. Based on the past experience, and on projections on progresses in battery technology, in the near future it is wise to expect only small improvements in the battery capacity. Therefore, it is extremely important to manage energy efficiently. The Minitrack focuses on the design and analysis of strategies for reducing the energy consumption in mobile and pervasive computing systems. The nine papers selected address several hot topics in this new exciting research field. They have been organized into three sessions. Papers in the first session investigate Energy-aware Solutions for Pervasive Computing. Harris and Cahill try to minimize the power consumption of stationary desktop PCs in a pervasive computing office. They propose and implement two location aware policies that detect a user’s Bluetooth-enabled mobile phone. Naik, Biswas and Datta present a distributed sleep scheduling protocol that can be used for implementing synchronous interface sleep for energy conservation in (IEEE 802.11) ad hoc networks. Galluccio, Leonardi, Morabito and Palazzo focus on neighbour discovery in ad hoc and sensor networks. They introduce an analytical framework that allows a tradeoff between energy consumption and timely detection in the neighbour discovery process. The second session is devoted to Power Management in Sensor Networks. Tang and Raghavendra propose a multi-hop tripwire detection and cueing scheme for energy conservation in sensor networks. The proposed solution overcomes the false alarm and exposed alarm problems. Schiller, Liers, Ritter and Voight present ScatterWeb, a distributed platform for the deployment of embedded sensor networks, and propose an energy-aware routing scheme that is an extension of the directed diffusion algorithm. Wang, Basagni, Melachrinoudis and Petrioli explore the idea of exploiting sink mobility for increasing the lifetime of a wireless sensor network. They attempt to maximize the network lifetime as a function of sink movements and sojourn time at different positions. Papers in the third session deal with Energy-efficient Access Technologies. Oikonomou and Stavrakakis investigate TDMA-based topology-unaware Medium Access Control (MAC) policies that employ probabilistic and deterministic approaches to minimize energy consumption. Baccarelli, Biagi, Pellizzoni and Cusani propose an iterative, decentralized, asynchronous, and scalable power-control and signal-shaping algorithm for ad hoc networks affected by multiple-access interference. The proposed algorithm forms the basis for the design of a novel connection admission procedure. Finally, Phan, Glisic and Luong propose adaptive linklayer schemes that lower the number of retransmissions over wireless links to save the energy of a mobile device, while maintaining the performance of TCP connections.