Low-Complexity Time-Domain DBP Based on Random Step-Size and Partitioned Quantization

• Published in: Journal of lightwave technology 2018-07, Vol.36 (14), p.2888-2895
• Main Authors: Martins, Celestino S., Bertignono, Luca, Nespola, Antonino, Carena, Andrea, Guiomar, Fernando P., Pinto, Armando N.
• Format: Article
• Language: English
• Subjects: Algorithms; Back propagation; Bandwidths; Complexity; Complexity theory; Digital backpropagation; digital signal processing; Fiber optic networks; Finite impulse response filters; FIR; Hardware; Impulse response; Measurement; nonlinear compensation; Nonlinear optics; Optical fiber communication; optical fiber communications; Quantization (signal); Size distribution; Time domain analysis; Wavelength division multiplexing
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2018.2829774

We propose and experimentally validate a low-complexity time-domain (TD) digital backpropagation (DBP) algorithm for fiber nonlinearity compensation, targeting an optimized hardware implementation. To counteract the coherent accumulation of numerical quantization errors between DBP steps, we propose a random step-size distribution along the optical link (with ±5% interval around the optimal step-size). In addition, to further reduce the average quantization bit precision requirements, we propose a partitioned quantization technique, enabling to quantize the finite-impulse response (FIR) filter tail coefficients with significantly lower precision. The proposed low-complexity DBP algorithm is experimentally demonstrated over a 2592 km long-haul wavelength division multiplexing transmission system with 21×32 GBaud PM-16QAM optical channels. Employing the proposed step-size randomization together with dual-time-slot quantization, we demonstrate penalty-free operation at an average of ~4 b per FIR coefficient, leading to a 60% complexity reduction when compared to the standard TD-DBP implementation.