Date of Award

16-2-2024

Document Type

Thesis

School

School of Electrical & Electroncis Engineering

Programme

Ph.D.-Doctoral of Philosophy

First Advisor

Dr.R.Jayabharathy

Keywords

Cooperative NOMA, NOMA, OMA, Index Modulation

Abstract

The global Pandemic/COVID-19 keeps people connected through wireless commu- nication. The tremendous growth of mobile data traffic and an increase in massive IoT connectivity among different devices leads to a scarcity of wireless resources. One of the advancing technologies for the 5G Beyond communication network, Non-Orthogonal Multiple Access (NOMA), is used for M2M, V2V, and connecting low-power IoT devices. NOMA outperforms OMA schemes such as FDMA, TDMA, CDMA, and OFDMA of 1G, 2G, 3G, and 4G in terms of data rate, latency, and spectral efficiency. NOMA exploits the multiplexing of signals in the power domain with the same frequency/time, and the interfered signal can be decoded at the receiver using Successive Interference Cancellation (SIC).

An indicator of Quality of Service (QoS), the Fairness Index ranges from 0 to 1 and gauges how evenly resources are distributed among users connected to a given system. Jain’s Fairness Index (JFI) of NOMA is higher than that of OMA for variable transmit power. Two NOMA users have a JFI of 0.85, whereas that of OMA users have a JFI of 0.6. With the NOMA systems, this guarantees the QoS and massive connection. After developing the NOMA system-level design with SystemVue, results are attained. SIC is considered perfect in most of the work, but it is not so in real-time scenarios. The performance of NOMA integrated with MIMO systems under imperfect SIC is analyzed. The Bit-Error Rate (BER) and Capacity of the suggested system are impacted by the SIC residual term. The analysis of the effect of the power allocation coefficient on the system’s performance highlights the importance of proper power distribution.

The MIMO-NOMA system can use co-operative methods to boost system reliability. The use of many Radio Frequency (RF) chains increases the power consumption and complexity of detection for MIMO-NOMA implementation. This further leads to Inter-Channel Interference (ICI) and Inter Antenna Synchronization (IAS). Implementing Index Modulation (IM) methods, such as Spatial Modulation (SM), in the NOMA system, provides a potential solution to these problems. The UR-SM-CNOMA system, which stands for User Relaying Cooperative NOMA with SM, is suggested. A recursive algorithm for maximizing the sum capacity of UR-CNOMA to obtain the optimal power allocation factor.

The simulation compares the proposed system to the established User Relaying Cooperative NOMA (UR-CNOMA) system using the analytically determined results, ensuring the effectiveness of the proposed method. Simulation results of the sum capacity of UR-SM-CNOMA for different spatial locations of near user are depicted, and conditions for the site of near user and far user are obtained to outperform SM-OMA. The existing MIMO antennas are not well exploited, and the suggested system only supports a limited number of users. An upgraded IM method known as Fully Generalized Spatial Modulation is used in the proposed three-user C-NOMA (FGSMN) system to address these problems.

Maximum Sum Capacity (MSC) and recursive algorithms are two recommended power allocation ways to improve the optimal power allocation. The suggested system’s optimal power allocation enhances the sum and achievable capacity. In addition to per- forming a computational complexity analysis, it is found that the FGSMN system’s Jain’s Fairness Index (JFI) is superior. The sum capacity of FGSMN is calculated as 573 Mbps/𝐻𝑧 for a bandwidth of 100 𝑀𝐻𝑧 at a transmit power of 5 𝑑𝐵𝑚. The beamforming and power allocation simulation results for the NOMA system for M2M applications are provided.

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