Cross Evaluation of Waveform Modulation Schemes Using Postexperimental Field Data

This article extends the data dithering reuse (DDR) method to waveform modulation for underwater acoustic communications and enables postexperimental cross evaluation between single-carrier modulation (SCM) and orthogonal frequency-division multiplexing (OFDM). The proposed DDR method reuses the data from the original experimental scheme (OES) to evaluate a new scheme under test with different waveform modulations by adding dithering and reverse dithering, respectively, to the transmitted and received OES data. The proposed DDR method consists of three steps: 1) data block preparation; 2) waveform dithering; and 3) channel estimation and reverse dithering. OFDM signals with cyclic prefix or zero-padding guard intervals can be evaluated with the SCM of different constellation orders and vice versa. We demonstrate the effectiveness of the proposed cross-evaluation method using multiple-input multiple-output (MIMO) field measurements from the undersea 2008 Surface Processes and Acoustic Communications Experiment, compared to the original experimental data sets and existing residual prediction error (RPE)-enhanced replay simulations. The MIMO soft-decision frequency-domain Turbo equalization is used to detect both the SCM and OFDM schemes. The results confirm that the average bit error rate (BER) and the BER distribution predicted by the proposed DDR method are closer to the OES evaluation and are more robust than the RPE-enhanced replay simulation.