180 Gb/s PAM8 Signal Transmission in Bandwidth-Limited IMDD System Enabled by Tap Coefficient Decision Directed Volterra Equalizer

Li, Di; Song, Haiping; Cheng, Wu; Deng, Lei; Cheng, Mengfan; Fu, Songnian; Tang, Ming; Liu, Deming

doi:10.1109/access.2020.2968128

Cited by 8 publications

(6 citation statements)

References 28 publications

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“…5 shows the measured BER performance of RLS-FFE, the conventional KK algorithm with RLS-FFE, LMS-VE, and RLS-VE in terms of different Vpp values at the ROP of 0 dBm after 40 km SSMF transmission. By considering the tradeoff between equalization performance and computational complexity [9], the memory length of FFE and VE is set to (55) and (55,45,0), respectively. The sampling rate of the KK algorithm is set to 6 samples per symbol [12].…”

Section: Simulation Setup and Resultsmentioning

confidence: 99%

“…For example, in a 112 Gbit/s PAM4 short reach transmission using a directly modulated laser [1], a three-order VE is used for nonlinear post-compensation. By using the proposed tap coefficient decision-directed VE, 180 Gbit/s PAM8 signals are successfully transmitted over 2 km standard single-mode fiber (SSMF) in an IMDD system with 10-dB bandwidth of 17.5 GHz [9]. On the other hand, the IC algorithm treats the SSBI term as a perturbation to be calculated and subtracted [10].…”

Section: Introductionmentioning

confidence: 99%

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A Robust Sparse RLS-Volterra Nonlinear Equalizer Using ℓ₀-Regularization for 4 × 150 Gbit/s IMDD-Based Optical Interconnect

Cheng

Song

et al. 2021

IEEE Access

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Volterra equalizer (VE) is a well-known and effective algorithm to deal with the linear and nonlinear distortions in optical interconnect, but the high computational complexity hinders its practical application. Generally, sparse VEs based on ℓ 1-or ℓ 0-regularization are good ways to reduce the complexity by discarding some inessential taps. However, a tap threshold needs to be chosen in these sparse VEs like the threshold-based pruned retraining VE (TR-VE) to decide the discarded taps. And this tap threshold should be adjusted fine to balance the reduced complexity and equalization performance, especially when the testing environments alter. Thus, the reduced complexity in these sparse VEs may fluctuate. To address this issue, a robust and stable complexity reduced sparse VE using ℓ 0-regularization (ℓ 0-SR-VE) is proposed in this paper. The recursive least square (RLS) algorithm is used to replace the least mean square algorithm for the faster convergence speed and better equalization performance. The complexity of this equalizer depends on its parameters but not the tap threshold. Once the equalizer parameters are determined, the complexity would not change with the system characteristics, contributing to higher practicability. In our experiment, a 150 Gbit/s PAM8 signal transmission system based on intensity modulation and direct detection (IMDD) is achieved, and a dual-drive Mach-Zehnder modulator for optical single-sideband signal generation is used to mitigate the power fading effect. The experimental results show that with the help of ℓ 0-SR-VE, the reduced complexity percentage is stable at 66.18% compared with the RLS-based VE, even after 75 km standard single-mode fiber (SSMF) transmission. By using this equalizer, 4×150 Gbit/s PAM8 signals have also been successfully transmitted over 30 km SSMF at C-band. The reduced complexity variation of ℓ 0-TR-VE is >20%, but the reduced complexity of the proposed ℓ 0-SR-VE is stable at 60% even after 30 km SSMF for all four lanes. INDEX TERMS PAM8, IMDD system, data center interconnect (DCI), sparse Volterra equalizer (VE).

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Section: Simulation Setup and Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Robust Sparse RLS-Volterra Nonlinear Equalizer Using ℓ₀-Regularization for 4 × 150 Gbit/s IMDD-Based Optical Interconnect

Cheng

Song

et al. 2021

IEEE Access

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“…Hence, increasing the capacity using SiP-modulators requires challenging their bandwidth, and operating in the bandwidth-limited regime. At high symbol rates, bandwidth-limited IMDD systems suffer from the strong intersymbol interference (ISI) that requires powerful equalization at the receiver [9,10]. However, the powerful equalization amplifies the high-frequency noise within the signal bandwidth and reduces the SNR, which has been reported by several studies and is referred to as equalizerenhanced in-band noise [11,12].…”

Section: Introductionmentioning

confidence: 99%

2D Constellation Distortion for Subduing Equalization Noise in Bandwidth- Limited IMDD Systems

Berikaa

Alam

Jacques

et al. 2022

IEEE Photon. Technol. Lett.

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Bandwidth-limited IMDD systems suffer from the noise boosted by the strong equalization at the receiver. This paper proposes a multiplication-free approach that reduces the impacts of the equalizer-enhanced colored noise through time-interleaving the received symbols and distorting the two-dimensional (2D) constellation such that the noise correlation is subdued. The 2D distortion map is predefined and retrieved from a look-up table. The proposed 2D constellation distortion is evaluated after the linear feed-forward equalizer and Volterra nonlinear equalizer. Experimental results show a BER reduction of 40% when the 2D constellation distortion is employed after the equalizer for the 135 Gbaud PAM4 and 110 Gbaud PAM6 signals. Owing to the proposed approach, we transmit a net data rate of 250 Gbps/λ PAM4 and PAM6 in the O-band over 2 km of SSMF at a BER of 3.8×10 -3 below the 6.7% overhead HD-FEC using a 47 GHz SiP modulator, linear equalization, and the proposed 2D distortion.

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“…In recent years, the requirement for alternatives to digital coherent transmission in short-reach applications has spawned a series of studies on direct detection (DD) systems due to their low cost, high power efficiency, and easy implementation [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Some schemes have been proposed in the published literature.…”

Section: Introductionmentioning

confidence: 99%

“…To improve the spectral efficiency, high-order modulation formats are adopted. The most common is the pulse-amplitude modulation (PAM) scheme, which encodes information at multiple amplitude levels, such as PAM-4 [7] and PAM-8 [8]. However, the reception sensitivity will be significantly reduced as the level increases.…”

Section: Introductionmentioning

confidence: 99%

DLI-Based DP-QPSK Reception Scheme for Short-Range Optical Communication

Yin

Huang

2020

Applied Sciences

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The unacceptably high cost of digital coherent receivers for short-range optical communication has in recent years fueled the study of alternative transmission schemes that are simultaneously highly performing and cost-effective. However, the proposed solutions (e.g., Kramers–Kronig receiver) usually require the cooperation of a transmitting end, which is unachievable in the context of non-cooperative communication. In this work, we mainly studied a dual-polarization quadrature phase-shift-keying (DP-QPSK) non-coherent reception scheme based on a delay-line interferometer (DLI) and measures to improve the reception performance. A data recovery algorithm was proposed for DLI-based DP-QPSK demodulation. The simulation results demonstrated that the algorithm could accurately recover the raw data from the transmitter. Moreover, decreasing the differential delay of the DLI could effectively increase the chromatic dispersion tolerance of the receiver and the optimal delay scaled inversely with the chromatic dispersion. It was found that a DLI-based DP-QPSK reception scheme is a better choice for short-range, non-cooperative communication with less severe transmission impairments.

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180 Gb/s PAM8 Signal Transmission in Bandwidth-Limited IMDD System Enabled by Tap Coefficient Decision Directed Volterra Equalizer

Cited by 8 publications

References 28 publications

A Robust Sparse RLS-Volterra Nonlinear Equalizer Using ℓ₀-Regularization for 4 × 150 Gbit/s IMDD-Based Optical Interconnect

A Robust Sparse RLS-Volterra Nonlinear Equalizer Using ℓ₀-Regularization for 4 × 150 Gbit/s IMDD-Based Optical Interconnect

2D Constellation Distortion for Subduing Equalization Noise in Bandwidth- Limited IMDD Systems

DLI-Based DP-QPSK Reception Scheme for Short-Range Optical Communication

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