Dynamic Spectrum Access: From Cognitive Radio to Network Radio
Dynamic spectrum access is a new spectrum sharing paradigm that allows secondary users to access the abundant spectrum holes or white spaces in the licensed spectrum bands. DSA is a promising technology to alleviate the spectrum scarcity problem and increase spectrum utilization. While DSA has attracted many research efforts recently, in this paper, the authors discuss the challenges of DSA and aim to shed light on its future. They first give an introduction to the state-of-the-art in spectrum sensing and spectrum sharing. Then, they examine the challenges that prevent DSA from major commercial deployment.