Efficient Real-Time Digital Subcarrier Cross-Connect (DSXC) Based on Distributed Arithmetic DSP Algorithm

• Published in: Journal of lightwave technology Vol. 38; no. 13; pp. 3495 - 3505
• Main Authors: Xu, Tong, Fumagalli, Andrea, Hui, Rongqing
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.07.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Arithmetic; Channels; Distributed arithmetic; DSXC; Field programmable gate arrays; Finite impulse response filters; FIR filters; FPGA; frequency translation; Hardware; OFDM; Optical filters; Real time; Real-time systems; Resampling; resampling filter; Subcarriers; Table lookup; Time functions
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2019.2937787

Two real-time functions of digital subcarrier cross-connect (DSXC) are experimentally demonstrated for the first time using distributed arithmetic (DA) in a field programmable gate array (FPGA) platform. Both frequency translation and channel selection in DSXC are implemented using DA-based resampling filters, achieving flexible modulation format and fine data-rate granularity of many concurrent subcarrier channels. Compared with traditional resampling filters that leverage multipliers, the DA-based approach eliminates the need for DSP slices in the FPGA implementation and significantly reduces the hardware cost. By requiring only a few clock periods, the DA-based resampling filter is also significantly faster when compared to conventional FIR filters, whose overall latency is proportional to the filter order. The DA-based DSXC is therefore able to achieve improved spectral efficiency and programmability of multiple orthogonal subcarrier channels, while keeping low cross-connection latency and requiring low cost hardware resources when implemented in a FPGA platform.