O.N. Chirkov1, M.A. Romashchenko2, I.V. Sviridova3, N.V. Tsipina4

1-4 Voronezh State Technical University (Voronezh, Russia)

Formulation of the problem. Let us consider an efficient adaptive filtering algorithm for estimating a channel with OFDM orthogonal frequency multiplexing using the example of underwater acoustic communication. The impulse response of an underwater acoustic communication channel is often sparse. Sparse adaptive filters are used to identify the channel. Channel estimation is a difficult task due to the large delay spread and the rapid change of the acoustic channel over time. To obtain good channel estimation performance, adaptive algorithms such as Least Mean Squares (LMS) and Classical Recursive Least Squares (RLS) are widely used. However, these algorithms provide slow convergence and have high arithmetic complexity compared to sparse RLS adaptive filters.

Purpose. Investigate the use of additive filters to improve the performance of underwater acoustic channel estimation in high-speed data transmission with orthogonal frequency division multiplexing OFDM.

Results. The use of normalized adaptive LMS filters (NLMS) and sparse adaptive RLS filters in UWA underwater acoustic communication channels with OFDM modulation has been studied. An adaptive filter with a sliding window is proposed for channel estimation in high-speed data transmission in underwater acoustic communications. The simulation results showed that the proposed adaptive filter with a sliding window outperforms normalized adaptive filters in bit error BER and outperforms additive filters with an exponential window in the number of mathematical operations.

Practical significance. Considering the sparsity of the channel impulse response as an inherent property of underwater acoustic propagation, the proposed sliding window adaptive filter can significantly improve the channel estimation performance. When modeling wireless acoustic communication systems with OFDM, error-free data transmission with a spectral efficiency of 0.33 bit/s/Hz was achieved.

Chirkov O.N., Romashchenko M.A., Sviridova I.V., Tsipina N.V. An efficient adaptive filter with a sliding window for estimating
a communication channel with orthogonal frequency multiplexing. Radiotekhnika. 2022. V. 86. № 7. P. 50−55.
DOI: https://doi.org/10.18127/j00338486-202207-09 (In Russian)

1. Zakharov Y.V., Nascimento V.H. Sparse RLS adaptive filter with diagonal loading. Conference Record of the Forty Sixth Asilomar Conference on Signals, Systems and Computers (ASILOMAR). IEEE. 2012. Р. 806-810.
2. Zakharov Y.V., Nascimento V.H. DCD-RLS adaptive filters with penalties for sparse identication. IEEE Transactions on Signal Processing. 2013. V. 61. № 12. Р. 3198-3213.
3. Chirkov O.N. Jeffektivnyj algoritm dinamicheskogo rasprostranenija pilot-signalov dlja ocenki kanala radiosvjazi v mnogoantennyh sistemah MIMO s ortogonal'nym chastotnym uplotneniem OFDM. Radiotehnika. 2019. T. 83. № 6(8). S. 163-168 (In Russian).
4. Romashhenko M.A., Chirkov O.N., Churakov P.P. Usovershenstvovannyj metod ocenki kanala s iteracionnym podavleniem pomeh dlja mnogopol'zovatel'skih sistem MIMO-OFDM. Radiotehnika. 2019. T. 83. № 6(8). S. 150-155 (In Russian).
5. Romashhenko M.A., Chirkov O.N., Churakov P.P. Jeffektivnyj algoritm ocenki kanala radiosvjazi s prostranstvennoj moduljaciej. Radiotehnika. 2021. T. 85. № 6. S. 52-56 (In Russian).
6. Chirkov O.N. Prjamoe formirovanie OFDM-signalov. Vestnik Voronezhskogo gosudarstvennogo tehnicheskogo universiteta. 2012. T. 8. № 5. S. 54-56 (In Russian).
7. Chirkov O.N. Povyshenie pomehoustojchivosti vysokoskorostnoj besprovodnoj sistemy obmena informacii Wi-fi. Vestnik Voronezhskogo gosudarstvennogo tehnicheskogo universiteta. 2011. T. 7. № 3. S. 66-67 (In Russian).