In search of energy-efficient mobile networking

With the proliferation of mobile fixed-power devices, energy consumption emerged as a vibrant research and development subject area in networking. Mobile devices are designed with several hard constraints such as low cost and small geometries, as well as, low heat dissipation, and operation using fixed power sources. Manufacturers have been adding an ever increasing set of features to small mobile devices, which are no longer binary-use gadgets, but fully-fledged computers. With respect to power management, several mechanisms have been introduced; but, by and large, gains in power consumption at the hardware level have been essentially traded for extended functionality. All in all, the overall operational time has not increased. For example, early GSM cellular phones could only allow for less than an hour of talk time in a single battery charge. By the late 1990s, top models, introduced through better engineering and an evolutionary development approach, featured talk times increased by a factor of 3-5. This level of performance has remained the same over the last decade, although it is well below user expectations. This article reviews the evolution from simple cell phones toward the feature-rich mobile networked devices we have come to expect from manufacturers, and explains the factors that have led to stagnation in operational time. We then turn our attention to the multiaccess nature of modern mobile devices and the respective implications for power management. We find that the current host-centric mobile networking paradigm, based on end-to-end always on connectivity, leads to energy-inefficient operation. Finally, this article introduces information-centric networking and outlines open research issues in the design of energy-efficient future Internet architectures.