Equalisasi Berbasis Training Sequence Untuk Komunikasi Akustik Bawah Air

Hanafiah, Rayhan Ermanno (2026) Equalisasi Berbasis Training Sequence Untuk Komunikasi Akustik Bawah Air. Other thesis, Institut Teknologi Sepuluh Nopember.

Text 5048221015-Undergraduate_thesis.pdf Restricted to Repository staff only Download (20MB) | Request a copy

Abstract

Komunikasi akustik bawah air digunakan untuk transmisi data di lingkungan perairan karena gelombang elektromagnetik mengalami redaman tinggi di dalam air. Namun, kanal akustik bawah air memiliki karakteristik kompleks berupa multipath, delay spread, efek Doppler, dan sifat berubah terhadap waktu, yang menimbulkan inter-symbol interference (ISI) dan menurunkan kinerja sistem komunikasi. Penelitian ini merancang dan mengevaluasi sistem komunikasi akustik bawah air berbasis OFDM-QPSK dengan estimasi kanal berbasis Least Square (LS) menggunakan blok pilot serta empat metode equalizer, yaitu Zero Forcing (ZF), Minimum Mean Square Error (MMSE), Least Mean Square (LMS), dan Recursive Least Square (RLS). Evaluasi dilakukan melalui dua pendekatan: pengukuran langsung di kolam uji tarik (towing tank) BRIN pada variasi jarak 5–50 m dengan dua frekuensi sampling, yaitu 19922 Hz dan 44100 Hz, serta simulasi link-level pada kanal ideal untuk mengamati pengaruh derau AWGN tanpa dan dengan equalizer. Hasil pengukuran menunjukkan BER meningkat seiring bertambahnya jarak, dengan RLS konsisten memberikan BER terendah pada seluruh jarak uji, yaitu 0,087 pada jarak 5 m hingga 0,201 pada jarak 50 m, lebih rendah dibandingkan ZF, MMSE, dan LMS (0,15–0,30). Pada simulasi kanal ideal, penerapan equalizer menurunkan BER dari orde 10^-1 menjadi sekitar 3×10^-3 pada SNR 30 dB. Penelitian ini juga menunjukkan bahwa konsistensi representasi sinyal antara sisi pemancar dan penerima merupakan aspek penting dalam sistem OFDM akustik bawah air.
=====================================================================================================================================
Underwater acoustic communication is used for data transmission in aquatic environments because electromagnetic waves experience high attenuation in water. However, underwater acoustic channels exhibit complex characteristics such as multipath propagation, delay spread, Doppler effects, and time-varying behavior, which cause inter-symbol interference (ISI) and degrade system performance. This study designs and evaluates an OFDM-QPSK-based underwater acoustic communication system employing Least Square (LS) pilot-based channel estimation and four equalization methods, namely Zero Forcing (ZF), Minimum Mean Square Error (MMSE), Least Mean Square (LMS), and Recursive Least Square (RLS). The evaluation was carried out through two approaches: direct measurements in the BRIN towing tank at distances of 5–50 m under two sampling frequencies, 19922 Hz and 44100 kHz, and link-level simulation over an ideal channel to observe the effect of AWGN without and with equalization. The measurement results show that the BER increases with distance, with RLS consistently achieving the lowest BER across all tested distances, ranging from 0.087 at 5 m to 0.201 at 50 m, lower than ZF, MMSE, and LMS (0.15–0.30). In the ideal-channel simulation, equalization reduces the BER from the order of 10^-1 to about 3×10^-3 at 30 dB SNR. This study also shows that consistency of signal representation between the transmitter and receiver is an important aspect in underwater acoustic OFDM systems.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Underwater Acoustic Communication, Training Sequence, Adaptive equalization, LMS, RLS, Multipath Channel
Subjects:	T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK5101 Telecommunication
Divisions:	Faculty of Intelligent Electrical and Informatics Technology (ELECTICS) > Telecommunication Engineering > 20202-(S1) Undergraduate Thesis
Depositing User:	Rayhan Ermanno Hanafiah
Date Deposited:	28 Jul 2026 01:40
Last Modified:	28 Jul 2026 01:40
URI:	http://repository.its.ac.id/id/eprint/138196

Actions (login required)

View Item