and information, and represents a novel marketing paradigm shift from conventional passive energy consumers to active energy prosumers.

![An example of virtualizing wireless network for XaaS[]{data-label="fig:example"}](virtu.jpg){height="8cm" width="10cm"}

Challenges for enabling XaaS
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An example of virtualizing the wireless network for XaaS is shown in Fig. \[fig:example\]. In this example, end-users connect to the virtual network from which they require the services, and they also connect to the cellular network physically to obtain the actual services. In the WNV, a physical network controller and a virtualized network controller need to be deployed between the virtualized wireless networks and physical wireless networks to realize the virtualization process [@Liang]. We can see that enabling WNV for XaaS confronts many challenges from the interaction of two networks, virtual resource allocation, network infrastructure management and involved signalling issues. In the following, we elaborate these challenges and their impact on XaaS development.

Signalling
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Due to the inherent broadcast nature of wireless communications and randomness character of wireless channel, WNV is more challenging to be realized and provided [@Liang]. In the process of virtualizing the wireless network, connectivity need to be firstly created between the NSPs and InSPs. By such, the communications and negotiation between the 