저피탐 수중음향통신에서 훈련 신호 구간의 오차율에 기반한 레이크 수신기

Abstract

In recent years, underwater sensor networks can be used for environment monitoring, disaster prevention, and military surveillance. When sound waves are passed through the underwater, they are affected by attenuation, reflection of bottom and surface, scattering, ambient noise, and the Doppler effect caused by movement of the transmitter and the receiver.

In this thesis a type of channel and the channel parameters are investigated to calculate the counter-detection range in underwater acoustic communication channels. A rake receiver that uses the BER (bit error rate) analysis of train signals was proposed, which have the better performance than a conventional rake receiver. A conventional rake receiver selects the paths which are the matched filter output over threshold. Weights are allocated to selected paths in accordance with path gains. A proposed rake receiver uses the same method to a conventional rake receiver which is path selection, but that uses BER analysis of each path under threshold in the training sequence to assign weights. In accordance with training sequence BER the weights are allocated, the lower train BER the high weighting value. After the envelop of received signals are used in channel fading analysis, the channel types and channel parameters are investigated by curve fitting of the amplitude variability. After the ROC (receiver operating characteristic) curve are calculate by the channel types and channel parameters, as a result, counter-detection range are attained by calculating detection probability in accordance with false alarm probability. In the event of lake experiments the channel type is Rayleigh fading channel. Consequently ROC curve and counter-detection range are analyzed. A non-rake receiver, conventional rake receiver, and proposed rake receiver performance are evaluated in lake experiments. As a result, proposed rake receiver have the error free performance and conventional rake receiver have 12.5% BER performance.