Adaptive turbo equalizer for underwater acoustic differential orthogonal frequency-division multiplexing systems

Credit: CC0 Public Domain

In mobile underwater acoustic communications (UAC), the relative movement between the transceivers will cause Doppler spread in the received signal, which will bring inter-carrier interference to the orthogonal frequency-division multiplexing (OFDM) UAC system, thereby distorting the transmitted symbols. The design of a high-performance low-complexity receiver in mobile OFDM UAC systems remains a difficult problem.

In a study published online in the journal IEEE Transactions on Vehicular Technology, the researchers from the Institute of Acoustics of the Chinese Academy of Sciences (IACAS) proposed an adaptive turbo equalizer (TEQ) for differential OFDM systems.

Taking advantage of the soft information fed back from the channel decoder, the researchers reconstructed the symbols on each subcarrier of the OFDM system. Then, they utilized the adaptive TEQ to eliminate the residual inter-carrier interference induced by estimated symbols, thereby improving the block error rate (BLER) performance of the system.

The coefficients of

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