Advanced NOMA techniques for spectral and energy efficiency in next-generation wireless networks

Abstract

The evolution of wireless communication beyond fifth-generation (5G) and towards sixth-generation (6G) networks necessitates advancements in spectral efficiency, energy efficiency, and massive connectivity. To address these demands, non-orthogonal multiple access (NOMA) has emerged as a promising multiple access scheme that enables multiple users to share the same resources efficiently. However, practical challenges such as multi-user interference, error propagation in successive interference cancellation (SIC), imperfect channel state information (CSI), and transceiver hardware impairments (HIs) significantly impact system performance. Additionally, the increasing demand for self-sustainable communication has motivated the exploration of energy harvesting (EH) and backscatter communication (BC), which improve energy efficiency by utilizing ambient radio frequency signals. The thesis investigates advanced NOMA-based frameworks that integrate HQAM, EH, and BC to enhance wireless systems’ spectral and energy efficiency under realistic constraints.