Reconfigurable Wireless Networks

Driven by the advent of sophisticated and ubiquitous applications, and the ever-growing need for information, wireless networks are without a doubt steadily evolving into profoundly more complex and dynamic systems. The user demands are progressively rampant, while application requirements continue to expand in both range and diversity. Future wireless networks, therefore, must be equipped with the ability to handle numerous, albeit challenging, requirements. Network reconfiguration, considered as a prominent network paradigm, is envisioned to play a key role in leveraging future network performance and considerably advancing current user experiences. This paper presents a comprehensive overview of reconfigurable wireless networks and an in-depth analysis of reconfiguration at all layers of the protocol stack. Such networks characteristically possess the ability to reconfigure and adapt their hardware and software components and architectures, thus enabling flexible delivery of broad services, as well as sustaining robust operation under highly dynamic conditions. The paper offers a unifying framework for research in reconfigurable wireless networks. This should provide the reader with a holistic view of concepts, methods, and strategies in reconfigurable wireless networks. Focus is given to reconfigurable systems in relatively new and emerging research areas such as cognitive radio networks, cross-layer reconfiguration, and software-defined networks. In addition, modern networks have to be intelligent and capable of self-organization. Thus, this paper discusses the concept of network intelligence as a means to enable reconfiguration in highly complex and dynamic networks. Key processes in network intelligence, such as reasoning, learning, and context awareness, are presented to illustrate how these methods can take reconfiguration to a new level. Finally, the paper is supported with several examples and case studies showing the tremendous impact of reconfiguration on wireless networks.

I. INTRODUCTION

The last few years have witnessed an incredible revolution in wireless networks. The number of wireless devices worldwide continues to increase at an enormous rate, and the applications of wireless networks are getting increasingly versatile, sophisticated, and ubiquitous. Thus, future wireless networks are expected to operate under several challenging conditions. First, they are expected to provide efficient always-on reliable high data rate access. Second, they have to be energy efficient for the sake of user convenience and for environmental concerns, since the widespread of wireless devices leads to significant increase in their total energy consumption and greenhouse gas (GHG) emission. Indeed, information and communication systems consume over 10% of the world's total energy [1]. Third, wireless networks have to consider challenging and changing user demands (video traffic over mobile devices now accounts for over 50% of global data traffic [2]). Fourth, users expect their devices to be smart, to learn about their interests, and to provide them with information that is timely and convenient (over 2 billion smartphone subscriptions have become available in 2014 [3]). Last but not least, the spread of cloud resources and big data centers, together with the advent of the Internet of Everything (IoE), promise to provide wireless users with unprecedented services and opportunities.