5G waveform design and software defined radio based proof of concept implementations

Communication engineering field is a rapidly advancing field where related systems are served to high number of users and demand on these systems brings new challenges. Especially for mobile communications, communication resources are becoming more and more limited. There are efforts in communication engineering field to meet the requirements. However, because of the speed of the increase in the number of users and integration with various new sectors, these efforts seem ineffective. Particularly with the new trends arising from novel 5G studies, in addition to overcoming the limitations, significant improvements in communication quality are also becoming a necessity. With these targets, it is visioned that crucial data which has a financial importance, will be transmitted over mobile networks with the development of 5G. This fact brings additional challenges, especially from the security perspective. All these facts are investigated in this thesis and are analyzed separately in the following chapters. In Chapter 1, the importance of the scope of this thesis is highlighted and the main components of the chapters are explained. In Chapter 2, an introduction on the utilized methodology and software defined radio (SDR) technology is given. Considered topics in the scope of this thesis are novel topics and have an importance in 5G studies. Hence, compared to the state-of-the-art, real-time performance analysis becomes a must since current communication environment has some difficulties in the real-time channel. Most of the models may perform very deteriorated in such conditions and such performance loss can be enhanced with a proper real-time analysis. By targeting this, SDR technology is utilized in our studies in order to analyze their real-time performance. With the help of SDRs, experiments can be carried on in a way that symbols can be transmitted from transmitter to receiver nodes over the air. Implementation aspects of our studies are also explained. In Chapter 3, non-orthogonal multiple access (NOMA) technique is investigated and its real-time performance results are presented. To the best of authors' knowledge, first comprehensive SDR implementation of NOMA is realized in this study with broad real-time components. Moreover, a novel waveform is proposed in this study, which is entitled as superposition coded orthogonal frequency division multiplexing (SC-OFDM). Accordingly, proposed waveform has a certain performance advantage over standard OFDM. With detailed experiments, this claim is validated and details are given in the chapter. In Chapter 4, universal filtered multi-carrier (UFMC) waveform, which is an important waveform candidate for 5G networks, is implemented in real-time for the first time in the literature. Its main details, proposed additional methods and implementation aspects are explained. Then in Chapter 5, UFMC waveform is further investigated and four novel waveforms which are UFMC variations, are proposed. Precoding and single-carrier methodologies are exploited and detailed experiments are carried out. Related details are explained in this chapter. In Chapter 6, physical layer security (PLS) is evaluated and corresponding details are demonstrated. As mentioned, security of the transmitted data increases with new applications and proper methodologies are required. Accordingly, PLS is a leading candidate for next-generation networks and brings various benefits. In this study, a PLS scenario is modeled and the corresponding details are investigated. With experiments, it is shown that PLS models can be effective in the improvement of security levels. As the last chapter, thesis is summarized and main points are highlighted in Chapter 7.