Conclusion
This survey gave a brief overview of WSNs and SDN and introduced the concept of software-defined WSNs (SD-WSNs) including their operations, e.g., topology discovery and routing decisions, that are different from WSNs. Coordination of distributed nodes and energy efficiency are the most important challenges in WSNs. In non-SDN based WNSs, they are mostly solved in a distributed manner. SD-WSNs favor central control. That may save energy because redundant communication can be avoided, energy-constraint nodes can be offloaded from energy-efficient task by moving them to the controller, and application-specific goals may be achieved with fewer active nodes through more intelligent operation. We reviewed advances for WSNs through SDN and challenges for SD-WSNs that should be solved in the future. Finally, we pointed out lessons learned during the preparation of this survey.
