transparently to the NSPs or directly to the end-users. In the platform of RaaS, the radio resources can be abstracted, isolated, assigned and sliced properly according to the demands and requirements, and then are offered as a service. By such, the available radio resources can be utilized more efficiently by permitting different parties to share the same spectrum.

Data-and-Knowledge-as-a-service (DKaaS)
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The expansive wireless network is also emerging as a critical data contributor over the air-interface, which makes us entering the big data era [@Bi]. Big data virtualization can be viewed as one of the most valuable means through which to make sense of big data, and thus make it more approachable to the end-users and NSPs. Through virtualization, the big data can be abstracted, characterized and virtualized to more valuable knowledge, which can offer a shorter route to help decision making.

In this context, virtualization becomes a critical tool to convey information in all data analysis, which also induces the the proposal of Data-and-Knowledge-as-a-service (DKaaS). Meanwhile, due to the fact that the delivery of large amount of data over wireless networks truly occupies considerable amount of radio resources, such as spectrum, power, storage, or even backhaul, the data may 