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It is very important to estimate the signal to noise ratio (SNR) of receive signal accurately because this parameter will play an important role in the equalization and detection modules. LFM signal is often used as a synchronization signal due to its good autocorrelation property and Doppler tolerance in underwater acoustic (UWA) channels. A new SNR estimation algorithm making use of the LFM signal...
A parallel combinatory (PC) multicarrier frequency-hopped spread spectrum (FHSS) underwater acoustic (UWA) communication system is proposed in this paper. Parallel combinatory is first applied in FHSS system to accomplish the subcarrier mapping, which makes the communication system not only to preserve the ability of resisting fading and narrow band interference randomly during the transmission over...
It is tough to achieve higher transmit speed and lower bit error rate(BER) because of the complexity of the underwater acoustic channel. This paper proposes a method of orthogonal frequency division multiplexing (OFDM) modulation technique for improving the situation. It can reduce BER with the ability of resisting multi-path interference and can increase communication rate with the characteristic...
Signal modulation has an important impact on the system performance in optical communication. Two attractive modulation schemes are pulse position modulation (PPM) and multipulse PPM (MPPM), which have the advantage of average energy efficiency and bandwidth efficiency, respectively. An important practical issue is to employ an efficient channel coding of reasonable (decoding) complexity adapted to...
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