Quantitative Analysis of Deep-Sea Underwater Acoustic Multipath Channel Quality

In this work, several channel quality estimating indicators are compared and used to quantitatively analyze the influence of different deep-sea time-invariant multipath channel structures on the single-carrier underwater acoustic (UWA) communication performance. These quantitative indicators are known as delay spread, coherence bandwidth, spectral null depth and signal multipath ratio (SMR), which are only determined by the channel impulse response (CIR). Based on the deep-sea experimental data, the channel qualities of deep-sea convergence zone and shadow zone are qualitatively compared firstly using these indicators and it is found that the distribution of delay spread is not as regular as other indicators, whose distributions are similar to that of signal-to-noise rate (SNR) reflecting the distribution of convergence zone and shadow zone. Moreover, the correlations between various quantitative indicators of deep-sea UWA channel quality and bit error rates (BERs) after channel equalization are analyzed quantitatively to compare the performance of corresponding indicators. The experimental results of deep-sea trial indicate that, among these indicators, spectral null depth has the strongest correlation with BERs after equalization, meaning that it has an advantage to evaluate the impact of time-invariant multipath channel on the UWA communication.