Application of a digital non-linear compensation algorithm for evaluating the performance of root-raised-cosine pulses in 112 Gbit s⁻¹DP-QPSK transmission

Abstract

In this paper, we numerically investigate the non-linear tolerance of root-raised-cosine (RRC) pulse shaping by interpolating finite impulse response (FIR) filters in conjunction with digital backward propagation (DBP) in coherent 112 Gbit s −1 dual-polarization quadrature phase shift keying (DP-QPSK) transmission. The results depict that RRC pulses are more tolerant to intra-channel non-linearities, i.e. self-phase modulation (SPM), as compared to standard RZ-33 and NRZ pulses. The non-linear threshold point is improved by using RRC pulses by a factor of 2 dB signal input power as compared to RZ pulses and by 4 dB signal launch power as compared to NRZ pulses. The behavior of RRC pulses is also investigated with standard single mode fiber (SMF), non-zero dispersion shifted fiber (NZDSF) and next-generation large A eff pure silica core fiber (LA-PSCF). Most importantly multi-span DBP is implemented and in the case of RRC pulses the computational efforts of the conventional DBP algorithm are reduced by 80% with a diminutive Q-penalty of 0.74 dB. The duty cycle of the RRC pulses is further optimized for efficient system performance. We have also compared the performance of single-channel transmission with the multi-channel transmission, where the performance is limited due to inter-channel non-linear effects. Furthermore, the non-linear tolerance of RRC pulses is investigated with; (a) different amplifier spacing and (b) variation in transmission link design information for the DBP algorithm.

Signal Processing Algorithms for Down-Stream Traffic in Next Generation 10 Gbit/s Fixed-Grid Passive Optical Networks

“…The joint compensation of linear and nonlinear transmission impairments is implemented by inversely solving the nonlinear Schrodinger equation (NLSE), as in (1). This method is termed as digital backpropagation (BP) [2,[5][6][7][8][9][10][11][12], and it is a topic of high interest in recent years. We have implemented BP algorithm by using the simplest symmetric split-step Fourier method (SSFM) with constant step-size method [7], as in (2).…”

Evaluation of correlative coding and DP-16QAM n-channel 112Gbit/s coherent transmission: digital non-linear compensation perspective

“…To solve the issue, transmitter and receiver side digital signal processing (DSP) algorithms, termed as Digital Backward Propagation (DBP), to compensate chromatic dispersion and intra-channel non-linearities have been investigated in [18][19][20][21][22][23][24][25][26]. But the complexity of DBP algorithm is extremely high due to ultra-wide bandwidth requirements that it becomes an intrinsic impediment in the real-time implementation of DBP algorithm [27,28].…”

Hybrid opto-digital signal processing in 112 Gbit/s DP-16QAM and DP-QDB transmission for long-haul large- $$\hbox {A}_\mathrm{eff}$$ A eff pure-silica-core fiber links

“…The compensation of nonlinear effects through digital signal processing techniques [deterministic postprocessing through nonlinear Schrödinger equation (NLSE)] is an active area of research from the last few years to remove the major obstacle in long-haul transmission [9][10][11][12][13][14]. But this method requires huge computational efforts [15][16][17][18], making it impossible to be used as a real-time module with coherent receiver [19][20][21][22][23]. On the other hand, optical signal processing method to compensate XPM through periodic group-delay dispersion compensator and optical backward propagation (OBP) shows promising performance [24].…”