Performance comparison between packet and continuous data transmission using two adaptive equalizers in shallow water

Transmitted signals are markedly affected by sea surface and bottom boundaries in shallow water. The time variant reflection signals from such boundaries characterize the channel as a frequency-selective fading channel and cause intersymbol interference (ISI) in underwater acoustic communication. A...

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Bibliographic Details
Published in:Japanese Journal of Applied Physics 2015-07, Vol.54 (7S1), p.7
Main Authors: Yoon, Jong Rak, Park, Kyu-Chil, Park, Jihyun
Format: Article
Language:English
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Summary:Transmitted signals are markedly affected by sea surface and bottom boundaries in shallow water. The time variant reflection signals from such boundaries characterize the channel as a frequency-selective fading channel and cause intersymbol interference (ISI) in underwater acoustic communication. A channel-estimate-based equalizer is usually adopted to compensate for the reflected signals under this kind of acoustic channel. In this study, we apply two approaches for packet and continuous data transmission of the quadrature phase shift keying (QPSK) system. One is the use of a two-dimensional (2D) rotation matrix in a non-frequency-selective channel. The other is the use of two equalizers of types - the feed forward equalizer (FFE) and decision-directed equalizer (DDE) - with a normalized least mean square (NLMS) algorithm in a frequency-selective channel. The percentage improvement of packet transmission is notably better than that of continuous transmission.
ISSN:0021-4922
1347-4065
DOI:10.7567/JJAP.54.07HG05