Leveraging software-defined networking for modular management in wireless sensor networks

Abstract

Wireless sensor networks (WSNs) are becoming increasingly popular with the advent of the internet of things (IoT). Various real-world applications of WSNs such as in smart grids, smart farming, and smart health would require a potential deployment of thousands or maybe hundreds of thousands of sensor nodes/actuators. To ensure the proper working order and network efficiency of such a network of sensor nodes, an effective WSN management system has to be integrated. However, the inherent challenges of WSNs such as sensor/actuator heterogeneity, application dependency, and resource constraints have led to challenges in implementing effective traditional WSN management. This difficulty in management increases as the WSN becomes larger. Software-defined networking (SDN) provides a promising solution for flexible management of WSNs by allowing the separation of the control logic from the sensor nodes/actuators. The advantage with this SDN-based management in WSNs is that it enables centralized control of the entire WSN making it simpler to deploy network-wide management protocols and applications on demand. Therefore in a comprehensive literature review, this study highlights some of the recent work on traditional WSN management in brief and reviews SDN-based management techniques for WSNs in greater detail. All this while drawing attention towards the advantages that SDN brings to traditional WSN management. This study also investigates open research challenges in coming up with mechanisms for flexible and easier SDN-based WSN configuration and management. A profound research challenge uncovered in the literature review is the need for an SDN-based system that would provide an opportunity for rapid testing and implementation of management modules. Therefore, this study proposes SDNMM, a generic and modular WSN management system based on SDN. SDNMM introduces the concept of management modularity using a management service interface (MSI) that enables management entities to be added as modules. The system leverages the use of SDN in WSNs and by being modular it also allows for rapid development and implementation of IoT applications. The system has been built on an open-source platform to support its generic aspect and a sample resource management module implemented and evaluated to support the proposed modular management approach. Results showed how adding a resource management module via the MSI improved packet delivery, delay, control traffic and energy consumption over comparable frameworks. However, SDN-based implementation comes at a cost of control overhead traffic which is a performance bottleneck in WSNs due to the limited in-band traffic channel bandwidth associated with WSNs. This has driven the research community to look into methods of effectively reducing the overhead control traffic in a process known as control message quenching (CMQ). In this study, a state of the art overview of control traffic reduction techniques available and being implemented for SDN-based WSNs is also presented. It provides an insight on benefits, challenges and open research areas available in the field of control message quenching for SDN-based WSNs. This study opens the door to this widely unexplored research area in its current form. Additionally, this study introduces a neighbour discovery control message quenching (ND-CMQ) algorithm to aid the reduction of neighbour reports in an SDN-based 6LoWPAN framework. The algorithm produces a significant decrease in control traffic and as a result shows improvements in packet delivery rate, packet delay, and energy efficiency compared to not implementing any CMQ algorithm and also compared to an alternative FR-CMQ algorithm based on flow setup requests.