Generalized frequency division multiplexing–based acoustic communication for underwater systems

Abstract

The underwater (UW) acoustic channel poses multiple challenges like coloured ambient noise, frequency-dependent attenuation, and doubly selective fading. The availability of a robust underwater communication mechanism can largely enhance the success of human effort in a multitude of applications, ranging from pollution surveillance to defence and search/ rescue operations. In this work, generalized frequency division multiplexing (GFDM), a non-orthogonal multicarrier scheme, which has recently been studied for terrestrial wireless fading channels, is developed and tested for signalling in UW acoustic communication. UW noise, attenuation, and doubly selective fading channels are modelled with appropriate statistics. The BER performance of proposed system is systematically evaluated under different channel conditions, starting from simple additive white Gaussian noise (AWGN) and Rayleigh fading channels to a horizontally configured UW channel. The performance is also compared with contemporary orthogonal frequency-division multiplexing (OFDM)-and filter bank multicarrier (FBMC)-based systems. K E Y W O R D Sgeneralized frequency division multiplexing (GFDM), acoustic underwater (UW) communication, UW channel modelling 1 | INTRODUCTION Underwater (UW) communications have received a lot of research attention due to their wide variety of applications ranging across defence/warfare, oceanographic and seismic wave monitoring, oil explorations, search and rescue operations, aquatic life monitoring, and pollution control and disaster management. Such applications need the deployment of UW sensor networks, along with autonomous/tethered vehicles or devices in deep oceans. The main requirement of underwater sensor nodes and vehicles is possession of self-configuration ability so that they are able to communicate and coordinate among themselves in a robust manner. Establishing a reliable underwater wireless communication is the enabling technology for most of these requirements.Electromagnetic waves, especially RF waves and optical signals, have been tested for UW communication. The electromagnetic waves, however, suffer from large frequency-dependent attenuation and absorption in the sea water. Moreover, the approach is hazardous to marine life and also fails if the medium becomes less or non-conductive over time and geography. Sound waves are seen to achieve longer range with the same transmit power due to its physical nature. The highly time-varying and spatial-varying nature of the ocean medium poses a major challenge in the design and

Towards Multicarrier Waveforms Beyond OFDM: Performance Analysis of GFDM Modulation for Underwater Acoustic Channels

“…It can be modelled as colored Gaussian noise and added to the transmitted signal. As evident, the noise is location specific and it is observed that the noise amplitude is high at both lower and higher frequencies whereas it is at its minimum around 60 kHz [21].…”

“…Hebbar and Poddar (H&P) in [21] and [22] have analyzed a GFDM transceiver using statistical underwater acoustic channel model based on Rayleigh multipath fading. GFDM's low OOB leakages compared to CP-OFDM and the latter's ICI issue arising due to time variation/doppler spread, motivated H&P to explore GFDM for a doubly selective UWA channel.…”

Coded-GFDM for Reliable Communication in Underwater Acoustic Channels

“…It is observed that turbo codes outperform all other coding schemes investigated. Hebbar and Poddar [ 23 , 24 ] have proposed a GFDM modulated underwater acoustic transmission system. They used the Rayleigh distribution based multipath channel model along with ambient noise.…”

CPM-OFDM Performance over Underwater Acoustic Channels

“…The noise is location specific and can be modeled as color noise, and its amplitude is high at both the lower and upper end of the spectrum while minimum around 60 kHz [58].…”