  Traditional design of mobile wireless networks mainly focuses on ubiquitous
access and large capacity. However, as energy saving and environmental
protection become a global demand and inevitable trend, wireless researchers
and engineers need to shift their focus to energy-efficiency oriented design,
that is, green radio. In this paper, we propose a framework for green radio
research and integrate the fundamental issues that are currently scattered. The
skeleton of the framework consists of four fundamental tradeoffs: deployment
efficiency - energy efficiency tradeoff, spectrum efficiency - energy
efficiency tradeoff, bandwidth - power tradeoff, and delay - power tradeoff.
With the help of the four fundamental tradeoffs, we demonstrate that key
network performance/cost indicators are all stringed together.
