Multipath Analysis of Pruned DFT-Spread FBMC-OQAM in Underwater Acoustic Channels

During modulation, when each phase of subcarriers is the same or similar, the superimposed signal will be modulated by the same initial phase, resulting in a large instantaneous power peak, namely the higher peak-to-average power ratio (PAPR). After signals propagate through different paths, the interference is caused by the superposition of each component according to their respective phases, which distorts original signals or produces errors. To reduce the PAPR and resist the influence of long-time delays, we propose to employ the discrete Fourier transform spread filter bank multicarrier (DFT-spread FBMC) to achieve it. Different from general FBMC technologies, it adds a precoding matrix before the offset quadrature amplitude modulation (OQAM). By comparing with orthogonal frequency division multiplexing technology, this letter explores its PAPR performance under different delays. The results show that the pruned DFT-spread FBMC-OQAM has a lower PAPR and better performance in long-time delays underwater channels.