Improving the Phase Noise Tolerance of Subbanded DFT-Spread OFDM by Nonredundant Interleaving

DFT-Spread (DFT-S) OFDM is a variant of OFDM with multiple advantages, however, one disadvantage is its degraded phase noise tolerance, due to sampling rate slow-down in each DFT-S subband. Here, we propose a phase recovery method for 16-QAM coherent transmission, based on the combination of nonredundant (de)interleaving, differential precoding, and multisymbol delay detection (MSDD), applicable to either conventional DFT-S OFDM receivers or to filter-bank subbanded DFT-S OFDM receivers. Laser and nonlinear phase noise tolerances are significantly improved, as simulated for a filter-bank-based subbanded DFT-S OFDM receiver for 16-QAM over 1000 km SMF.