Underwater Acoustic Communication With an Orthogonal Signal Division Multiplexing Scheme in Doubly Spread Channels

Abstract

Underwater acoustic (UWA) communication is an ongoing challenge because of the heavy time spread by multipath and Doppler spreads. Here we propose a UWA communication system using orthogonal signal division multiplexing (OSDM), a scheme that measures the multipath profile without an adaptation or interpolation process, to achieve stable communication in doubly spread channels. We previously evaluated the performance of an OSDM scheme in a UWA communication system in both an experiment and simulations. In the present study, we experimentally compared the performance of OSDM and existing communication schemes -single-carrier with decision feedback equalizer (DFE) and orthogonal frequency division multiplexing (OFDM) -in a test tank with respect to communication quality, data rate, frame length, and calculation complexity. We found that OSDM with a multichannel receiver is attractive in terms of communication quality; it achieved a far better bit-error-rate (BER) performance compared to the other schemes in both static and dynamic channels with various input signal-to-noise ratios, although the complexity is less than that achieved with single-carrier DFE. Based on these findings, we suggest that OSDM can provide a highly reliable communication environment for UWA communication with multipath and Doppler spread, such as in shallow water.

Recent trends in multicarrier underwater acoustic communications

“…The proposed system had far better performance than the traditional decision feedback equalizer (DFE) in a channel with severe frequency selective fading, and its energy efficiency was 3 dB better than a system which uses a pilot signal. A UWA communication system using orthogonal signaldivision multiplexing (OSDM), a scheme that measures the multipath profile without an adaptation or interpolation process, to achieve stable communication in doubly spread channels was proposed in [60]. It was suggested that OSDM could provide a highly reliable communication environment for UWA communication with multipath and Doppler spread, such as in shallow water.…”

Autonomy and networking challenges of future underwater systems

“…Despite recent advances in underwater signal processing [20], the underwater acoustic channel will always be very limited relative to terrestrial communication standards. Even though a few publications report point-to-point data rates in the 1 to 10,000 bits/s range, reliable underwater communication is often achieved at much lower rates: 4-100 bits/s for point-to-point communication [21] and 8-40 bits/s for endto-end network communication between 5 to 9 nodes [22] separated by 1 km.…”

Channel Estimation for Orthogonal Time Frequency Space (OTFS) Massive MIMO

“…A Doppler-resilient orthogonal signal division multiplexing technique was proposed. That multiplexes several data vectors and a pilot vector into a data stream to fully exploit the frequency-time diversity in the time-variant channels [20], [21].…”