On the 2×2 DFT-spread space-time block code CO-OFDM for PDM optical communications

Abstract

This work presents the combining of two methods, which are discrete Fourier transform spread (DFT-spread) and 2×2 space time block codes (STBC), to improve the system performance for polarization division multiplexing (PDM) coherent optical orthogonal frequency division multiplexing (CO-OFDM) communication systems. The system performances are generally measured by the unit of bit error rate (BER). For 64-QAM, the communication length of 850 km can be achieved at the forward error control (FEC) limit.