A Study on the Equalizers in the Multi-carrier Modulation for High Speed Underwater Wireless Communication

摘要

Recently, the necessity of the underwater wireless communication increase, and demands for transmitting and receiving various data such as voice or high resolution data are increasing as well. The performance of coherent acoustic communication systems is highly dependent upon channel characteristics including multipath, spatial and temporal coherence, Doppler effects and ambient noise. An important feature of the process of the sound field formation in oceanic waveguides is the interference caused by the surface and bottom. This means multipath effect. The interference effects lead to the ISI (Inter-Symbol-Interference) .In this paper, we study the application of high speed data transmission in underwater channel to use the OFDM (Orthogonal Frequency Division Multiplexing) technique for robust the multi-path. And compare the equalizer performances of DFE(Decision Feedback Equalizer) with IEEE 802.11a WLAN equalizer. We confirm the performance of communication in underwater to use the model for actually underwater channel simulation model and experiment in small water tank. As a result of experiment in small water tank, we acquired the BER of modulation techniques. The result of simulation, IEEE802.11a WLAN equalizer is 3.16×l10~(-3), and BER of DFE is 3.92×10~(-3). The result of experiment, IEEE 802.11a WLAN equalizer is 9.23×10~(-3) , and BER of DFE is 1.15×10~(-2).