A DSP Implementation of OFDM Acoustic Modem
The success of multicarrier modulation in the form of OFDM in radio channels illuminates a path one could take towards high-rate underwater acoustic communications, and recently there are intensive investigations on underwater OFDM. In this paper, we implement the acoustic OFDM transmitter and receiver design of [4, 5] on a TMS320C6713 DSP board. We analyze the workload and identify the most time-consuming operations. Based on the workload analysis, we tune the algorithms and optimize the code to substantially reduce the synchronization time to 0.2 seconds and the processing time of one OFDM block to 1.7 seconds on a DSP processor at 225 MHz. This experimentation provides guidelines on our future work to reduce the per-block processing time to be less than the block duration of 0.23 seconds for real time operations.
Summary
This paper describes an implementation of an OFDM-based acoustic modem on a TMS320C6713 DSP board, including workload analysis and algorithmic/code optimizations. Readers will learn how the authors reduced synchronization to 0.2 s and achieved 1.7 s per-OFDM-block processing on a 225 MHz DSP and what trade-offs remain for meeting real-time block-duration constraints.
Key Takeaways
- Identify computational hotspots in an OFDM acoustic modem (synchronization, FFT, and per-block processing) through workload analysis.
- Optimize synchronization and FFT-related routines to substantially reduce run-time (demonstrated reductions to 0.2 s sync and 1.7 s per block on a 225 MHz DSP).
- Apply algorithmic and code-level optimizations specific to TMS320C67x-class fixed-point DSPs to improve throughput.
- Estimate and budget per-block processing time to evaluate whether an implementation meets real-time acoustic communication constraints.
Who Should Read This
Engineers and researchers implementing or optimizing OFDM-based underwater acoustic or embedded communication systems on DSP hardware, seeking practical guidance on profiling and reducing real-time processing cost.
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