This paper proposes a post-experimental field data
reuse method to test the single carrier modulation (SCM)
and orthogonal frequency division multiplexing (OFDM) signals
interchangeably for multiple access underwater acoustic (UWA)
communications. We call this approach the cross evaluation that
transforms a set of SCM or OFDM post-experimental field data
to their corresponding OFDM or SCM scheme under test (SUT)
via linear matrix operation such as fast Fourier transform (FFT)
and its inverse (IFFT). At the receiver side, we derived a general
framework of turbo equalization (TEQ) that alters the two
physical layer schemes but keeps the passband transmitted and
received data unchanged. Inherently, some efficient techniques
such as pre-cursor and post-cursor interference cancellation (IC),
and overlap adding (OLA) operations enhance the equivalence
of input and output (I/O) system model between the SCM and
OFDM. The proposed approach will bring the gap between the
SCM and OFDM, and evaluate the two physical layer schemes
under similar or tougher test conditions. The experimental results
of the undersea 2008 Surface Processes and Acoustic Communications
Experiment (SPACE08) have verified the feasibility of
the cross evaluation approach in terms of the BER benchmark.
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Development and Testing of an OFDM Physical Layer for the DESERT Simulator
The realization of efficient, robust, and adaptable applications for the emergent Internet of Underwater Things enables the sustainable and effective conservation and exploitation of our oceans and waterways. Recent advances have fo- cused on Orthogonal Frequency-Division Multiplexing (OFDM) physical layers for supporting applications requiring high data rates and swift adaptation to changing underwater conditions. This prompts the need of tools for testing new OFDM-enabled underwater solutions. To this aim, this paper presents the implementation and evaluation of an OFDM-based physical layer module for the popular underwater network simulator DESERT. We aim at modeling the flexibility of the software-defined acoustic SEANet modem by realizing OFDM features that can vary in time, including the number and the selection of subcarriers and their modulation on a per-transmission basis. We demonstrate the usage of the proposed module through the DESERT-based simulation of three simple OFDM-enabled cross-layer MAC protocols in underwater acoustic networks of different sizes. The diverse and detailed set of results are obtained by using our physical layer module simply and swiftly. Our results also confirm the advantages of using the OFDM technology in solutions for underwater networking in challenging environments.
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- Award ID(s):
- 1726512
- NSF-PAR ID:
- 10298729
- Date Published:
- Journal Name:
- MTS/IEEE OCEANS 2021
- Page Range / eLocation ID:
- 1-8
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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