An error floor reduction scheme for DPSK receivers impaired by phase noise

A technique for reducing the error floor of differential phase-shift-keying (DPSK) receivers impaired by phase noise is introduced and analyzed. In the proposed (optical) DPSK receiver, the bandwidth of integrate-and-dump (I&D) filters are decreased so that multiple samples per symbol duration of the received signal are made available to the post-detection and decision circuitry. The proposed post-detection circuitry, referred to as the one-bit-shifted expanding-window (OBSEW) post-detection processing scheme, correlates the acquired samples that are centered about the signal transition point in a two-symbol signaling interval. For a phase-noise-limited operation, it is shown that the proposed OBS-EW scheme achieves an error floor that is significantly smaller than that of a conventional DPSK receiver