Reliable OFDM Data Transmission with Pilot Tones and Error-Correction Coding in Shallow Underwater Acoustic Channel

Abstract

The performance of Underwater Acoustic Communication (UAC) systems are strongly related to the specific propagation conditions of the underwater channel. Horizontal, shallow-water channels are characterised by extremely disadvantageous transmission properties, due to strong multipath propagation and refraction phenomena. The paper presents the results of communication tests performed during a shallow, inland-water experiment with the use of a laboratory model of a UAC system implementing the Orthogonal Frequency-Division Multiplexing (OFDM) technique. The physical layer of data transmission is partially configurable, enabling adaptation of the modulation and channel coding parameters to the specific propagation conditions. The communication tests were preceded by measurement of the UAC channel transmission properties. Based on the estimated transmission parameters, four configurations of OFDM modulation parameters were selected, and for each of them, communication tests were performed with the use of two Error-Correction Coding (ECC) techniques. In each case, the minimum coding rate was determined for which reliable data transmission with a Bit Error Rate (BER) of less than 10 − 4 is possible.

A Method for Underwater Wireless Data Transmission in a Hydroacoustic Channel under NLOS Conditions

“…This is mainly due to the high variability of the propagation environment over time, especially in shallow waters [ 13 ], hence the great interest of reliable and efficient methods of wireless acoustic communication underwater. In the literature, the wireless underwater acoustic communication systems using linear frequency modulation [ 14 ], BPSK, QPSK and 4-QAM modulations [ 15 , 16 , 17 ], as well as proposals for the use of the OFDM technique [ 18 , 19 ] can be found. However, the authors of those system worked under LOS conditions and did not checked the performance of their systems under NLOS conditions.…”

Application of Diversity Combining with RLS Adaptive Filtering in Data Transmission in a Hydroacoustic Channel

“…At the moment, the hydroacoustic channel remains the best transmission medium [ 1 ]. Unfortunately, despite great progress in the field of telecommunications, the possibility of utilization of an underwater acoustic channel (UAC) for communication is very limited and there is still intensive research on new solutions [ 2 , 3 ]. Channel limitations result from complex physical phenomena related to sound propagation in water.…”