Efficient Long-Distance Underwater Wireless Communication Using CP-GS-KF and SATR-ANN Techniques in a UWA-OFDM System

Abstract

For long-distance wireless communication in underwater environments, Underwater Acoustic (UWA) communication serves as a vital solution. However, UWA communication faces challenges like lower data rates and the time-varying nature of the UWA Channel, including the presence of the Doppler Effect. To overcome these limitations, this paper proposed an Underwater Acoustic-Orthogonal Frequency Division Multiplexing (UWA-OFDM) communication system employing a Cosine Probability Distributed Golden Search Optimized Covariance State Induced Kalman Filter (CP-GS-KF) and Semi-Averaged Trend Removed Artificial Neural Network (SATR-ANN) approach. Here, the data bits undergo convolution coding and interleaving at the transmitter before being modulated using Henkel Function First Kind-employed Quadrature Phase Shift Keying (HFFK-QPSK). Cyclic Prefix (CP) addition and upsampling are applied to ensure reliable transmission. The pulse shape is accurately recognized using a Perfectly Positive Auto Correlated-Raised Cosine Filter (PPA-RCF), followed by efficient upconversion. The baseband signal is transformed into a digital representation at the receiver end and synchronized for further processing. For decreasing the effects of the Doppler effect and estimating the channel, the CP-GS-KF and SATR-ANN techniques are employed, respectively. Several essential steps, namely downconversion, downsampling, CP elimination, frequency domain conversion, and equalization, are then executed. Lastly, the received signals are demodulated using HFFK-QPSK and decoded to recover the original data. By achieving a significantly reduced Bit Error Rate (BER) of 0.1986, Symbol Error Rate (SER) of 0.0203 during channel estimation using SATR-ANN, and removing the Doppler effect using CP-GS-KF with a Mean Square Error (MSE) of 0.12% that is lower than existing EKF, the proposed UWA-OFDM system demonstrates its superiority through extensive simulations and comparisons with prevailing approaches.