Geleneksel dik olmayan çoklu erişim (NOMA) ve NOMA'nın işbirlikli iletişim ve uzaysal modülasyonla birlikte uygulanması: Hatalı ardışık girişim engelleyici (SIC) altında performans değerlendirmesi ve analizi

In recent years, exponential increase in connected devices (i.e., smart-phones, tablets, watches etc.) to the internet and with the introduce of the Internet of Things (IoT), future radio networks (FRN) are keen to serve massive users in dense networks which is called as Massive Machine Type Communication (mMTC) -one of the three major concepts of 5G and beyond-. Non-orthogonal Multiple Access (NOMA) is seen a strong candidate for mMTC in FRN due to its high spectral efficiency and ability to support massive connections. In NOMA, users are assigned into same resource block to increase spectral efficiency and the most attracted scheme is power domain (PD)-NOMA where users share the same resource block with different power allocation coefficients. The interference mitigation in PD-NOMA is held by successive interference canceler (SIC). Due to its potential for 5G and beyond, NOMA has attracted tremendous attention from researchers where NOMA is widely investigated mostly in terms of achievable rate and outage probability. However, in those work mostly perfect SIC is assumed at the receivers which is not that reasonable assumption considering the fading channels. In addition, whereas numerous efforts have been devoted to investigating NOMA in terms of capacity and outage, one of the most important key performance indicators (KPIs): bit/symbol error rate (BER/SER) has not been regarded. These two major concerns about NOMA have initially motivated us to do this PhD research. This work aims to investigate three KPIs (capacity, outage and BER) of NOMA with imperfect SIC. Then, the same analysis is done for the interplays of NOMA with cooperative communication and spatial modulation (SM). Firstly, conventional NOMA (downlink and uplink) networks is analyzed under imperfect SIC and exact closed-from expressions for ergodic capacity (EC), outage probability (OP) and bit error probability (BEP) are derived over fading channels. All derived expressions are validated via computer simulations. The interplay between NOMA and cooperative communication is one of the most attracted NOMA related topics in the literature. This interplay is divided into three concepts: 1) cooperative-NOMA (C-NOMA) where strong NOMA users act as relays for weaker users to improve reliability of them. 2) relay-assisted/aided-NOMA where dedicated relays help source serving to NOMA users. 3) NOMA based cooperative relaying system (CRS) where NOMA is applied for different symbol of the destination to improve the inefficiency of device-to-device cooperative communication. All three concepts have been analysed in terms of the same performance metrics (i.e., EC, OP, BEP) under imperfect SIC and have been validated via Monte Carlo simulations. Then, threshold-based selective cooperative NOMA (TBS-C-NOMA) have been proposed to eliminate the effect of error propagation in C-NOMA and it is proved that TBS-C-NOMA outperforms C-NOMA and achieves full diversity order. In order to neutralize the decay in BER of conventional NOMA networks, the spatial multiple access (SMA) and Space Shift Keying (SSK)-NOMA have been introduced as alternatives to two users and multiple users multiple-input-multiple-output (MIMO)-NOMA networks. Closed form expressions of EC, OP and BEP have been derived for both systems and the derived expressions have been validated via computer simulations. Then, a comprehensive evaluation of NOMA involved systems is presented by extensive simulations. It is proved that NOMA outperforms orthogonal multiple access (OMA) techniques in terms of EC and OP. However, due to the inter-user interference (IUI), NOMA cannot compete with OMA networks. Thus, the trade-off between capacity and reliability of NOMA networks is emphasized and it is revealed that NOMA design should be handled considering the target reliability of networks. In addition, the performance improvement of the proposed TBS-C-NOMA scheme are presented compared to C-NOMA schemes. Furthermore, based on the extensive simulation results, it is proved that the proposed SMA and SSK-NOMA systems outperform their NOMA counterparts in terms of all three performance metrics (i.e,, EC, OP and BER). Moreover, the effect of power allocation on the performances of NOMA involved systems are investigated and the optimum power allocation in terms of three KPIs is discussed. Finally, all results are discussed and the thesis is concluded with the opportunities, challenges and the insights for future researches.