Iterative Phase Noise Mitigation in OFDM Communication Systems Using an ICI Reduction Scheme with Channel Estimation

Phase noise in OFDM systems has been the main reason for the abolishment of the subcarrier orthogonally, and thus, the common phase error and inter-carrier interference that result have been the main causes of BER, synchronization, and spectral efficiency degradations. To keep the above advantages of the system, it is indispensable to mitigate the phase noise effect in order to maintain signal integrity, improve channel estimation, and guarantee the proper functioning of high-speed communication, mainly in millimeter-wave and optical systems. Conventional channel estimation methods are based on the assumption of stable carrier phases and perfect orthogonality of subcarriers. When there is a strong phase noise, these assumptions become invalid, which in turn causes corrupted pilot symbols, incorrect channel estimates, and loss of synchronization. Consequently, the channel responses are no longer trustworthy, which results in poor equalization and increased bit error rates. To address these challenges, this manuscript proposes Iterative Phase Noise Mitigation in OFDM Communication Systems using an ICI Reduction Scheme with Channel Estimation (PNM-OFDM-ICIR-CE). Initially, historical phase noise samples are gathered from past OFDM transmissions to serve as the basis for analysis. The collected PN samples are incorporated to refine the channel estimates, improving system accuracy. An incoherent oscillator in the OFDM system is used to enhance performance and reduce phase noise in the transmitter and receiver. The phase noise arises due to the non-linearity of incoherent oscillators leading to ICI. To mitigate this ICI, Deep-Unfolded Joint Hybrid Beamforming (DUJHB) is applied. The channel estimation is performed and exploiting the inherently sparse nature of the optical channel. Finally, an iterative process is conducted, where each iteration improves phase noise mitigation using the latest channel estimates by simultaneously refining channel estimation through updated PN compensation. This results in effective PN mitigation and improved Bit Error Rate (BER) performance. The proposed PNM-OFDM-ICIR-CE method is implemented and the efficacy is examined under several performance metrics, like BER, Peak to average Power Ratio (PAPR), Power Spectral Density (PSD) and Signal Noise Ratio (SNR). The efficiency of proposed method is evaluated to existing techniques like Empirical modelling and analysis of phase noise in OFDM systems (EM-PN-OFDM), Impulse noise mitigation and channel estimation method in OFDM systems depending on TMSBL (INM-CE-OFDM) and Analysis of phase noise for DFT-spread OFDM systems in coherent optical communication (PN-DFT-OFDM) respectively