Performance Evaluation of the Complex-Coefficient Adaptive Equalizer Using the Hilbert Transform

• Published in: Journal of Information and Communication Convergence Engineering, 14(2) Vol. 14; no. 2; pp. 78 - 83
• Main Authors: Park, Kyu-Chil, Yoon, Jong Rak
• Format: Journal Article
• Language: English
• Published: 한국정보통신학회JICCE 30.06.2016; 한국정보통신학회
• Subjects: 전자/정보통신공학; Quadrature phase-shift keying; Inter-symbol interference; Feed-forward equalizer; Least mean squares algorithm; Underwater acoustic communication
• ISSN: 2234-8255; 2234-8883
• DOI: 10.6109/jicce.2016.14.2.078

In underwater acoustic communication, the transmitted signals are severely influenced by the reflections from both the sea surface and the sea bottom. As very large reflection signals from these boundaries cause an inter-symbol interference (ISI) effect, the communication quality worsens. A channel estimation-based equalizer is usually adopted to compensate for the reflected signals under the acoustic communication channel. In this study, a feed-forward equalizer (FFE) with the least mean squares (LMS) algorithm was applied to a quadrature phase-shift keying (QPSK) transmission system. Two different types of equalizers were adopted in the QPSK system, namely a real-coefficient equalizer and a complex-coefficient equalizer. The performance of the complex-coefficient equalizer was better than that of two real-coefficient equalizers. Therefore, a Hilbert transform was applied to the real-coefficient binary phase-shift keying (BPSK) system to obtain a complex-coefficient BPSK system. Consequently, we obtained better results than those of a real-coefficient equalizer. KCI Citation Count: 1