Proposals of multipath time-variant channel and additive coloured noise modelling for underwater acoustic OFDM-based systems

摘要

This paper presents the results of Underwater Acoustic (UWA) channel measurements, including the power delay profile and the Doppler power spectrum, and further uses them to analyse the Orthogonal Frequency Division Multiplexing (OFDM) system performance. The UWA channel simulation model is derived from the measurement data by applying a widely optimisation algorithm called the Lp-norm method. The close match of correlation functions of the measured and channel simulation model demonstrates correctness of our proposed channel modelling. Moreover, we also propose to use the Autoregressive (AR) generation method for characterising ambient noise in UWA systems. From the UWA channel simulation and coloured noise models, performance of OFDM system using different channel estimation techniques is investigated to analyse the impact of acoustic medium as multipath, Doppler and coloured noise effects. The numerical results manifest superior improvements of the so-called sparse channel estimation over other traditional ones such as least squares or minimum mean square estimation.