1536-1284/19/$25.00 © 2019 IEEE IEEE Wireless Communications • December 2019 64 ABSTRACT IoT has revolutionized the modern way of life with the advent of intelligent systems. The tradi- tional network architecture employed in the IoT domain is unable to define sufficient solutions of these challenges for a cost-effective and seam- less workflow. The intelligent IoT system ensures scalability in challenging or hostile environments. With the emergence of the SDN domain offering programming ability of the control plane, many of these challenges seemed surmountable. This article presents a synergized overview of the chal- lenges faced by the traditional domain and how they can be overcome by the upcoming domain of SDN-IoT. A thorough analysis of the practical adoptions showcase the feasibility of the solution in a real-time environment. The article examines the state of the art and highlights some of the key open points in the domain, based on shortcomings of the current state of SDN-IoT, that can be taken up for future research. INTRODUCTION The recent advancements made in the Internet of Things (IoT) domain paradigm are heralding remarkable transformations for improving the way of human life. The plethora of smart devices inte- grated with their actuation and sensing abilities, environmental awareness, and real-time analy- sis are making every aspect of modern society smarter and more efficient. For the purpose of achieving these goals, IoT devices must be able to interconnect and concurrently provision services that are backed by the back-end data storage sys- tems, while processing and assimilating the huge data generated by the various sensors and actu- ators [1]. The fact that the IoT domain employs a huge number of devices that can collect information in a real-time environment and at such a high frequency is perceived as its greatest strength. However, this also acts as a major bottleneck for the network. The complexity, heterogeneity, and associated limitations of the various devic- es require complex and specific tools for man- agement and for improving the performance of the network. The critical aspects associated with the performance and scaling of the net- work are often attributed to the characteristics of the devices and the proprietary architectures adopted by them. These issues cannot be solved by the mere introduction of a “gateway” like structure; challenges also emerge in the form of data aggregation, reliability, privacy, security, and trustworthiness. The capability and proto- col mismatch between the IoT devices accen- tuates when there is a huge number of devices deployed in a complex environment with varying protocols and varying designs. These problems become even more significant in real-time sce- narios like robotics and self-driven cars, where the exchange of real-time information also needs the applications to become scalable, efficient, seamless, and cost-effective. Unfortunately, how- ever, the current state of IoT technology alone cannot provision such requirements and over- come such challenges in an efficient manner [2]. Current state-of-the-art architecture for IoT devices is not capable of supporting features like mobility, higher scalability, and heavy traffic all at the same time along with the above mentioned functionalities. Moreover, with the number of connected IoT devices slated to grow exponen- tially over the next few years, it will become even more tedious to manage the mammoth amount of data generated by these devices without the inherent features of elasticity and flexibility of the network. In absence of these features, such a flood of data and traffic could paralyze the entire network. For overcoming these challenges faced by the IoT paradigm, upcoming technologies like software defined networking (SDN), OpenFlow architec- ture (based on SDN), and network function vir- tualization (NFV) are gaining major traction. The technology domain of SDN, specifically, has been receiving a lot of attention from the research community and has also proven its mettle in large deployments of data center networks optimizing the needs of IT and network resources [3]. SDN architecture aims at making networks flexible and agile. The primary objective of SDN is to bring about an improvement in network control by empowering service providers and enterprises to provide faster response to ever-evolving business requirements. In a software-defined network, the network administrator can control and monitor traf- fic without making any changes to the individual switches of the network. These switches are direct- ed by the centralized SDN controller to provision network services based on their requirement, irre- spective of the connections between the devices and the server. Pritish Mishra, Deepak Puthal, Mayank Tiwary, and Saraju P. Mohanty Sofware Defned IoT Systems: Properties, State of the Art, and Future Research FUTURE COMMUNICATION TRENDS TOWARDS INTERNET OF THINGS SERVICES AND APPLICATIONS Pritish Mishra and Mayank Tiwary are wtih SAP Lab; Deepak Puthal is with Newcastle University; Saraju P. Mohanty is with the University of North Texas. Digital Object Identifier: 10.1109/MWC.001.1900083