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Communication Dans Un Congrès Année : 2021

Adaptive optimization of OFDM Underwater Acoustic Communication parameters based on on-board channel simulations

Résumé

Self-configuration of modems is a key enabler to improve the efficiency and robustness of digital communications through underwater channels. More specifically, recent results have shown that designing adaptive PHY layers can be an efficient way to maintain some quality-of-service in changing soundscapes. Most adaptive approaches rely on estimated channel parameters (multipath spread, Doppler spread, SNR, etc. ) obtained by analyzing signals at reception and then forwarded to the transmitter through a feedback link. In some applications, such a link may not be feasible but higher-level information may be available. The aim of this work is to develop a method for the transmitter to automatically adapt its parameters based on the only information of the transmission geometry, that is: the transmitter/receiver depth, range, water depth and relative velocity. This work is part of the NEMOSENS project whose purpose is to develop swarms of micro AUVs for various oceanographic missions. Our objective is take advantage of the information of the AUVs location and speed that is periodically broadcasted. The modem uses a CP-OFDM waveform and we seek the optimal number of subcarriers (Nsub) and cyclic-prefix length (TCP) that should be used given some constraints on the overhead induced by TCP. Based on the transmission geometry, the proposed method runs an on-board wideband ray-tracer to predict the power-delay profile as well as a maximum-entropy based model to generate a Doppler power spectrum. The outputs of this simulated channel are then used to predict the interblock interference and inter-carrier interference expected at reception for each pair (Nsub, TCP). The optimal pair is considered to be the one that minimizes the total predicted interference. Performance of the proposed approach is tested in shallow-water environments using the Watermak simulator, which provides realistic channel conditions. In this scenario, the OFDM parameters of our optimization method turns out to match the set of parameters that minimize the bit-error-rate. The benefit of the proposed approach is to provide adaptive waveform optimization with the only knowledge of the channel geometry.

Dates et versions

hal-03285317 , version 1 (13-07-2021)

Identifiants

Citer

Camila Maria Gabriel Gussen, Christophe Laot, François-Xavier Socheleau. Adaptive optimization of OFDM Underwater Acoustic Communication parameters based on on-board channel simulations. UACE 2021: 6th Underwater Acoustics Conference & Exhibition, Jun 2021, (Virtuel), Greece. pp.030001, ⟨10.1121/2.0001498⟩. ⟨hal-03285317⟩
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