Real-time DSP-enabled digital subcarrier cross-connect based on resampling filters

A real-time digital signal processing (DSP)- enabled digital subcarrier cross-connect (DSXC) with resampling filters for channel frequency translation is demonstrated in this paper. This circuit-based DSXC supports flexible and fine data-rate subcarrier channel granularities, offering a low-latency data plane, transparency to modulation formats, and the capability of compensating for transmission impairments in the digital domain. The presented 8 × 8 DSXC demonstrator makes use of a Virtex-7 field programmable gate array (FPGA) platform, which supports any-to-any switching of eight subcarrier channels with mixed modulation formats and data rates. Digital resampling filters enable frequency translation of subcarrier channels at the cross-connect with much reduced processing requirements for the FPGA resources in comparison to the traditional technique based on in-phase/quadrature mixing and filtering.