Gelecek-nesil nesnelerin interneti için enerji ve tayf-verimli haberleşme teknikleri

Internet of Things (IoT) is a recent paradigm, rapidly gaining traction across a variety of disciplines, including but not limited to communications, electronics, computer engineering and social sciences. In its fundamentals, IoT provides a link between cyber and physical world by connecting devices over the Internet. Recent advances in hardware systems, signal processing and wireless communications have made it possible to manufacture low cost, low complexity wireless communicating things; which are the key to full scale adoption of the IoT paradigm. On the other hand, with the recent progress in nanotechnology, things are also quickly moving into to microscales and nanoscales. As the offspring of nanotechnology, nanomachines are strong candidates for realization of Internet of Bio-Nano Things (IoBNT). Full realization of IoT and IoBNT, however, will require surmounting of additional challenges. One of the upcoming difficulties is spectrum scarcity, which is a result of the inefficiency of the fi xed spectrum assignment paradigm. Additionally, most of the communicating entities are traditionally batter-powered and run out of batteries at fairly random instants after their deployment, which makes battery replenishments an unfeasible operation. With the scale game, rising need for self-sustainability and coordination is a clear reality. Whilst IoBNT opens doors for advanced applications such as nanoscale sensing and intelligent drug delivery, they depend on nanomachines with scarce processing, memory, and networking capabilities. There is clearly a need for energy and medium-efficient nanonetworking techniques, that would help nanomachines carry out more complex tasks, towards the IoBNT vision. To that end, in this thesis, we focus on energy and spectrum-efficient communication techniques for next-generation networks that are likely to constitute the backbones of IoT and IoBNT. We address key challenges brought by IoT and IoBNT applications, and solutions provided by next-generation networks and techniques thereof in two main parts: In Part I, we consider next-generation ad hoc networks, which are enhanced with energy and spectrum-efficient communication techniques to satisfy demanding future IoT functions. More specifically, architectures and techniques in Cognitive Radio Ad Hoc Networks (CRAHN) and Cognitive Radio Sensor Networks (CRSN) are studied to optimize performance in critical metrics such as sensing coverage, connectivity, spectrum- and energy-efficient communication duration and goodput-meters-per-Joule toward the fusion center. For future IoT applications in which demanding data rates cannot be achieved with today's traditional spectrum, a self-organizing capacity optimization procedure for low THZ band is developed. Lastly, a novel electric- field base energy harvesting method is proposed, tested and studied in detail to enable self-sustaining networks for real-life IoT applications. In Part II, we consider architectures that will help realization of nanonetworks, composed of nanomachines. Different communication types, namely; acoustic, electromagnetic, nanomechanical and molecular communications could be viable alternatives nanonetworking. However, acoustic and electromagnetic communications require entities that can carry out acoustic or electromagnetic operations at nanoscale. On the other hand, nanomechanical communications require direct contact between communicating parties and is not suitable for distant applications. In this context, we focused on Molecular Communications (MC) in this thesis, as it is a viable method for nanonetworking, backed by the fact that similar mechanisms are already present in many living organisms and environments. We extensively review in detail the existing modulation schemes in MC, and propose a novel messenger-based modulation scheme to increase channel performance in terms of achievable channel capacity without the need for synchronization.