Abstract
The Gaussian noise model is used to estimate the performance of three digital nonlinearity compensation (NLC) algorithms in C-band, long-haul, optical fiber transmission, when the span length and NLC bandwidth are independently varied. The algorithms are receiver-side digital backpropagation (DBP), transmitter-side DBP (digital precompensation), and Split NLC (an equal division of DBP between transmitter and receiver). For transmission over 100×100 km spans, the model predicts a 0.2 dB increase in SNR when applying Split NLC (versus DBP) to a single 32 GBd channel (from 0.4 dB to 0.6 dB), monotonically increasing with NLC bandwidth up to 1.6 dB for full-field NLC. The underlying assumptions of this model and the practical considerations for implementation of Split NLC are discussed. This work demonstrates, theoretically, that, regardless of the transmission scenario, it is always beneficial to divide NLC between transmitter and receiver, and identifies the transmission regimes where Split NLC is particularly advantageous.
Highlights
Inverse fiber parametersOptical Fiber (a) × NS digital precompensation (DPC)Optical Transmitter × NS EDFA (b) Optical Transmitter (c) × NS_DPC DPC Optical Receiver
The nonlinearity compensation (NLC) gain increases from 0.4 dB for conventional digital backpropagation (DBP), to 0.6 dB for Split DBP. This is because the performance of Split NLC versus DBP increases at long distances as the signal-amplified spontaneous emission (ASE) term becomes increasingly significant with the accumulation of ASE. (Note that a similar effect would be observed for shorter transmission distances provided similar accumulated ASE, for example due to high noise figure amplifiers or a larger fiber attenuation coefficient.) As is clear from Fig. 2(b), three channels would need to be simultaneously compensated using DBP in order to achieve the same gain as single channel Split NLC; greatly increasing the signal processing complexity
Using a theoretical model for signal-to-noise ratio after wide bandwidth optical fiber transmission, the performance of Split NLC was evaluated relative to transmitter-side (DPC) or receiver-side (DBP) digital nonlinearity compensation
Summary
In order to increase the data throughput of bandwidth-constrained, long-haul, optical fiber transmission systems, the signal-to-noise ratio (SNR), as measured at the receiver, must be improved. Since received SNR depends on all the noise contributions in a transmission link, including from within the receiver and transmitter, it is worth revisiting the commonly investigated digital signal processing (DSP) algorithms to ensure that they maximize SNR [1]. In this regard, the DSP-based optical fiber nonlinearity compensation (NLC) algorithm known as digital backpropagation (DBP) is of particular interest. Advances in NLC split between transmitter and receiver have lagged behind receiver-side NLC; possibly, again, due to the availability of DACs with comparable performance to ADCs, and due to the challenge of applying offline DSP simultaneously for signal predistortion and post-compensation. Considerations for practical implementations of Split NLC, in particular with regards to the influence of polarization mode dispersion (PMD), equalization enhanced phase noise (EEPN) and transceiver impairments are discussed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
