  Wireless Sensor Networks (WSNs) are the key components of the emerging
Internet-of-Things (IoT) paradigm. They are now ubiquitous and used in a
plurality of application domains. WSNs are still domain specific and usually
deployed to support a specific application. However, as WSN nodes are becoming
more and more powerful, it is getting more and more pertinent to research how
multiple applications could share a very same WSN infrastructure.
Virtualization is a technology that can potentially enable this sharing. This
paper is a survey on WSN virtualization. It provides a comprehensive review of
the state-of-the-art and an in-depth discussion of the research issues. We
introduce the basics of WSN virtualization and motivate its pertinence with
carefully selected scenarios. Existing works are presented in detail and
critically evaluated using a set of requirements derived from the scenarios.
The pertinent research projects are also reviewed. Several research issues are
also discussed with hints on how they could be tackled.
