A Hardware/Software Framework for MIMO-OFDM Waveform Design for Underwater Acoustic Communications

This abstract presents some preliminary results of an ongoing research on coherent communication for underwater acoustic communication (UWAC). In essence, this abstract presents a new hardware/software co-design framework for the analysis, synthesis, modeling, and simulation of sounding signals used in the characterization of multiple input multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) communication systems whose channels are randomly time-varying systems,  exhibiting time delay fading and Doppler frequency spreading. These channels are characterized as time-frequency channels and they are used to model the doubly dispersive nature of underwater acoustic communications channels.

The proposed novel hardware/software framework is based on the GNU radio architecture paradigm and it uses a digital signal processing unit as a hardware accelerator and signal generator. The framework also uses a general purpose ARM processor to serve as a data exchange process controller  as well as an application programming interface management host for the GNU radio computational platform and the digital signal processing unit.

The digital signal processing unit deals with the generation of diverse waveform patterns for communication signal processing tasks such as interference signal evaluation, pilot and chirp sounding signal transmission, and orthogonal signal constellation validation when modeling underwater acoustic MIMO-OFDM channels.  This functionality is accomplished through the development of a specialized digital floating-point signal processing library with multirate processing capabilities for acoustic signal processing operations. It is expected for the proposed framework to be able to work in real time simulation settings, addressing acoustic signal transmission and reception issues.