UACE2017 Proceedings: A novel two-step Doppler compensation scheme for coded OFDM underwater acoustic communication systems

Session:
Underwater Communications and Networking
Paper:
A novel two-step Doppler compensation scheme for coded OFDM underwater acoustic communication systems
Author(s):
Siyu Xing, Gang Qiao, Charalampos Tsimenidis
Abstract:
The performance of orthogonal frequency division multiplexing (OFDM) is gravely affected by the Doppler induced symbol dilation. Thus, it is important to compensate for this effect before detection. In this paper, we propose a combined Doppler effect estimation scheme for coded OFDM underwater acoustic communication systems. This scheme contains two steps; the first step is using the Fractional Fourier Transform to estimate the chirp rate change of the linear frequency modulation (LFM) signal, which is used as synchronization probe to obtain an initial Doppler effect estimate using the chirp-rate change. In the second step, cyclic prefix (CP) correlation is used to estimate the fine Doppler factor. We compare the proposed approach with state-of-the-art, time and frequency based resampling methods. The presented numerical results show that the proposed scheme can estimate the Doppler factor precisely after the two steps and match the performance of the resampling based approaches. However, the advantage of the two-step approach does not require the whole packet to be received, which in turn reduces the storage requirements and hardware resources, and thus, it is more suitable for the real-time implementation.
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