A New Low-Complexity Hybrid Equalization Method for LFDMA Systems

In this paper, a hybrid equalization technique is developed to overcome the adverse effects of inter-symbol interference (ISI) in localized frequency division multiple access (LFDMA) uplink broadband transmission systems. The loss in data transfer rate caused by multipath propagation in wireless communication distorts the signal and reduces transmission efficiency. The proposed modified Volterra–Wiener–Hammerstein (MVWH) equalizer combines modified Volterra and Wiener–Hammerstein nonlinear equalizers to achieve low-complexity equalization while enhancing data rate performance. Furthermore, the performance of both direct and reduced-complexity versions of the proposed MVWH hybrid equalizer is investigated using various signal quality measures for the LFDMA system. The performance of the proposed modified Volterra equalizer, which employs a low-complexity Volterra update in combination with a decision feedback equalizer (DFE), is also examined with respect to signal error and ISI induced by carrier frequency offset (CFO). The proposed hybrid system significantly improves LFDMA uplink transmission by providing an effective nonlinear inverse, thereby mitigating both linear and nonlinear signal impairments. Simulation results for the proposed hybrid approach are compared with other existing equalization systems and demonstrate superior performance in terms of bit error rate (BER), ISI mitigation, spectral efficiency and mean squared error (MSE). Compared to the standard Volterra equalizer, the proposed equalizer achieves a BER of 10[Formula: see text] with a signal-to-noise ratio (SNR) improvement of 1.2[Formula: see text]dB, while the reduced-complexity version achieves the same BER with an SNR improvement of 1.8[Formula: see text]dB.