SDN-Based Application Framework for Wireless Sensor and Actor Networks

As a promising platform for implementing various applications, a wireless sensor and actor network (WSAN) consists of many sensor and actor nodes that can cooperatively handle complex tasks. However, many issues, including nodes' mobility, the heterogeneity of capacity, topology, and energy consumption, may bring severe challenges to efficient WSAN operation. Currently, the software defined network (SDN) appears as a novel approach that is effective to manage and optimize networks in a programmable and centralized pattern. This paper studies the application framework and relevant methods for applying the SDN approach in a WSAN, with the objective of improving network's efficiency and scalability. The details of the framework include a three-layer structure, the relevant system entities, the enhanced protocol stack, and the programmable message types for cooperative communication and task execution among WSAN nodes. Based on this framework, this paper explores the relevant challenges and mechanisms for effective system management from many aspects, including mobility, energy saving, reliability maintenance, and topology construction. This paper also proposes an optimization method for scheduling decomposed tasks to relevant nodes, with an example implemented by the genetic algorithm. Next, this paper demonstrates the typical application scenarios, including military, industry, transportation, and environmental disaster monitoring. Moreover, an indoor application scenario and an outdoor application scenario are presented to demonstrate the application of the SDN-assisted communication handoff. Finally, the future trends and technical challenges for SDN in WSAN are discussed.