Low-complexity invasive weed optimization-assisted PTS and SLM framework for PAPR reduction in NOMA systems over fading channels

Information from the abstract

Non-Orthogonal Multiple Access (NOMA) is a key enabling technology for beyond fifth-generation (B5G) and sixth-generation (6G) wireless communication systems due to its high spectral efficiency and massive connectivity capabilities. However, the superposition of multiple user signals results in a high Peak-to-Average Power Ratio (PAPR), which degrades power amplifier efficiency, increases spectral leakage, and adversely affects system performance. To address this challenge, this paper proposes a low-complexity hybrid framework that integrates Invasive Weed Optimization (IWO) with Selective Mapping (SLM) and Partial Transmit Sequence (PTS) techniques for effective PAPR reduction in NOMA systems operating over Rayleigh and Rician fading channels. The IWO algorithm is employed to optimize phase sequences and phase weighting factors, thereby avoiding exhaustive search while maintaining low computational complexity. MATLAB 2016 simulations are conducted using a two-user NOMA system with 256-QAM modulation, 256 subcarriers, and ideal Successive Interference Cancellation (SIC) detection. Performance is evaluated in terms of Complementary Cumulative Distribution Function (CCDF), Bit Error Rate (BER), Power Spectral Density (PSD), and computational complexity. At a CCDF of 10 –4 , the proposed PTS + IWO scheme achieves PAPR values as low as 3.2 dB in Rayleigh fading and 2.1 dB in Rician fading, compared with approximately 12.8–13.3 dB for conventional NOMA. Furthermore, the proposed approach provides SNR gains of up to 3.5 dB at a BER of 10 –4 and significantly improves spectral containment with PSD levels reaching − 76 dB/Hz. The results demonstrate that the proposed IWO-assisted PTS framework offers an excellent trade-off between complexity, PAPR reduction, BER performance, and spectral efficiency, making it a promising solution for future high-efficiency NOMA communication systems.

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Related topics: Advanced Wireless Communication Technologies · PAPR reduction in OFDM · Advanced Wireless Communication Techniques