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E-book Dynamic Spectrum Management : From Cognitive Radio to Blockchain and Artificial Intelligence
Radio spectrum is a natural but limited resource that enables wireless communi-cations. The access to the radio spectrum is under the regulation of governmentagencies, such as the Federal Communications Commission (FCC) in the UnitedStates (US), the Office of Communications (Ofcom) in the United Kingdom (UK),and the Infocomm Development Authority (IDA) in Singapore. Conventionally, theregulatory authorities adopt thefixed spectrum access(FSA) policy to allocate dif-ferent parts of the radio spectrum with certain bandwidth to different services. InSingapore, for example, the 1805–1880MHz band is allocated to GSM-1800, andit cannot be accessed by other services at any time. With such static and exclusivespectrum allocation policy, only the authorized users, also known as licensed users,have the right to utilize the assigned spectrum, and the other users are forbiddenfrom accessing the spectrum, no matter whether the assigned spectrum is busy ornot. Although the FSA can successfully avoid interference among different appli-cations and services, it quickly exhausts the radio resource with the proliferation ofnew services and networks, resulting in the spectrum scarcity problem.The statistics of spectrum allocation around the world show that the radio spec-trum has been almost fully allocated, and the available spectrum for deploying new services is quite limited. The emerging of massive connections of internet-of-things(IoT) devices accelerates the crisis of spectrum scarcity. According to the study in[1], around 76GHz spectrum resource is needed for accommodating billions of enddevices by exclusive occupying the spectrum. Nevertheless, extensive measurementsconducted worldwide such as US [2], Singapore [3], Germany [4], New Zealand [5]and China [6], have revealed that large portions of the allocated radio spectrum areunderutilized. For instance, in US, the average occupancy over 0–3GHz radio spec-trum at Chicago is 17.4%. This number is even as low as approximately 1% at WestVirginia. In Singapore, the average occupancy over 80–5850MHz band is less than5%. These findings reveal that the inflexible spectrum allocation policy leads to aninefficient utilization of radio spectrum, and strongly contributes to the spectrumscarcity problem even more than the physical shortage of the radio spectrum.
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