A novel approach for peak-to-average power ratio reduction and spectral efficiency enhancement in 5G and beyond networks

High peak-to-average power ratio (PAPR), interference, and inefficient power allocation can severely limit the capacity of a filtered Non-Orthogonal Multiple Access (NOMA) system. This paper presents a novel structurally modified filtered NOMA system integrated with a Decomposed-based Selective Mapping (D-SLM) technique, to reduce high PAPR, and thereby increase spectral efficiency and enable effective spectrum sharing. The proposed f-NOMA-D-SLM (filtered Non-Orthogonal Multiple Access Decomposed-based Selective Mapping) system follows a process similar to that of the transmitter side of filtered NOMA, up to the encoding stage. After that, it incorporates three key components: (i) Walsh–Hadamard Transform (WHT), a mathematical technique that orthogonally transforms the superimposed signal into a non-sinusoidal form, (ii) D-SLM, and (iii) physical layer for dynamic spectrum access (PHYDYAS) filter, a prototype filter designed to minimize unnecessary signal distortion and dynamically mitigate undesired effects through improved frequency domain localization. At the receiver side, Successive Interference Cancelation (SIC) is applied to decode the signals for each user sequentially. The evaluation of the f-NOMA-D-SLM system is done at the receiver side under two scenarios: (i) without relaying and (ii) with cooperative diversity relaying. The performance demonstrates that f-NOMA-D-SLM handles interference better, thereby increasing system capacity and throughput, thus suiting advanced 5G and beyond networks.