Abstract
DSP-enhanced intensity-modulation direct-detection (IM/DD) systems can support up to 56 Gb/s over 100 km signal transmissions at C-band. To achieve higher data rates and longer transmission distances, we propose data-aided iterative algorithm (DIA) and decision-directed DIA (DD-DIA) to digitally mitigate signal-signal beating interference (SSBI) without requiring any modifications to physical layer structures. DIA utilizes pilot symbols with uniformly spaced insertions to relax the modified Gerchberg-Saxton (G-S) algorithms that suffer from the local optimum problem. To further improve the symbol error rate (SER) performance and convergence speed, DD-DIA introduces a decision process to generate pseudo-pilots. We numerically compare DIA with other algorithms and find that DIA can recover signals subject to large fiber dispersions corresponding to which conventional IA and Volterra filter (VF) fail, while DD-DIA significantly accelerates the convergence speed and improves the reconstruction performance compared with DIA, it can support 100-Gb/s PAM4 over 400-km IM/DD transmissions within just 50 iterations. Two orders of magnitude reductions in SER is observed for 100 Gb/s PAM4 signal transmission over 100-km SSMFs. Compared with conventional IA, the proposed techniques have higher convergence speeds, better global optimum features and large tolerances to physical model errors. In particular, DD-DIA results in larger optical signal-to-noise ratio (OSNR)/ received optical power (ROP) improvement, higher transmission capacities and less computational complexity. DD-DIA is a promising algorithm for efficiently reconstructing 2-dimensional optical field for conventional IM/DD optical transmission systems.
Highlights
INTRODUCTIONWITH the ever exponentially increasing requirement for long-haul and high-speed communications, electronic dispersion compensation (EDC) has matured and been
WITH the ever exponentially increasing requirement for long-haul and high-speed communications, electronic dispersion compensation (EDC) has matured and beenThe manuscript was received on xxx
We numerically compare data-aided iterative algorithm (DIA) with other algorithms and find that DIA can recover signals subject to large fiber dispersions corresponding to which conventional IA and Volterra filter (VF) fail, while directed DIA (DD-DIA) significantly accelerates the convergence speed and improves the reconstruction performance compared with DIA, it can support 100-Gb/s PAM4 over 400-km intensity-modulation direct-detection (IM/DD) transmissions within just 50 iterations
Summary
WITH the ever exponentially increasing requirement for long-haul and high-speed communications, electronic dispersion compensation (EDC) has matured and been. To enhance the transmission performance but without any physical structure modifications to conventional IM/DD optical transmission systems, several digital signal processing (DSP)-based performance enhancement algorithms have been presented to combat the effects including CD, the equalization-induced noise enhancement and transceiver nonlinearities These techniques include Volterra equalization [7], Tomlinson-Harashima precoding [8] and FDE-MLSE [9]. The square-law detected signal at the receiver, optimizations of the received optical field should be performed to ensure good matching between the estimated optical field and the real optical field after transmitting through the physical transmission system This is referred to as the local-optimum problem, which causes the first derivative of the convergence curve to approach zero even when the errors are still large. In order to efficiently linearize the IM/DD optical transmission systems in a low-cost way, in this paper, we introduce pilot symbols into the transmitted frames in the receiver to accelerate the convergence of the conventional iterative algorithms.
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