Wireless Network Virtualization: Opportunities for Spectrum Sharing in the 3.5 GHz Band

The three-tier model for spectrum sharing in the 3.5 GHz band, outlined in the PCAST report [1], has drawn considerable attention from stakeholders, researchers and policy-makers. In its Further Notice of Proposed Rulemaking, the FCC points out that “[t]he 3.5 GHz Band could be an “innovation band,” where we can explore new methods of spectrum sharing and promote a diverse array of network technologies, with a focus on relatively low-powered applications.” [2]. In this context, we evaluate the technical, economic and policy aspects of wireless network virtualization in this band. Wireless network virtualization has been proposed as a promising mechanism for granting increased opportunities for spectrum sharing, and thus enhancing the efficiency in spectrum usage. To date, we can find myriad definitions and applications of wireless network virtualization, most of them focusing on the technical implications and feasibility of this approach [3–7]. In fact, it has been pointed out that deeper levels of virtualization increase the flexibility of spectrum [6], thus providing us with significant opportunities to address problems of shortage and scarcity. Beyond the purely technical aspects of wireless virtualization, we focus on the advantages of this technique and its applicability to a broader set of spectrum sharing scenarios. We show that the benefits of virtualization can be leveraged for the deployment of secondary markets for spectrum since it offers a path toward increased market liquidity and viability. Indeed, in [8], an initial attempt toward linking wireless virtualization with existing spectrum trading scenarios [9,10] was made. The particular virtualization method adopted consisted in the creation of a pool of spectrum resources, consistent with what was presented in [7]. It was not surprising that benefits from virtualization were attained: the results obtained showed increased market viability opportunities. In this study, these benefits occurred because some of the physical complexities of electromagnetic spectrum no longer played a role in the market. In this paper, we explore the broader implications of virtualization in the spectrum sharing context. This requires analyzing the definitions and scope of virtualization and merging them with economic and regulatory characteristics intrinsic to the use of electromagnetic spectrum. Thus, we explore the conditions for the formation of pools of virtualized spectrum, the interaction between Priority Access users and General Authorized Access users; the requirements for economic feasibility and efficiency of such an approach and finally, the role played by regulation. This enables us to take into account characteristics pertinent to the stakeholders, to the physical spectrum resource and the appropriate framework in which they would interact. By following this path, we aim at shedding light on the advantages, boundaries and feasibility of spectrum sharing and trading in the 3.5 GHz band in a virtualized setting. In this manner, we would be able to obtain a more comprehensive view on what could be an efficient alternative for spectrum sharing by leveraging current technology advances and examining practical spectrum sharing scenarios.