Sofien Mhatli

Long-reach OFDM WDM-PON delivering 100 Gb/s of data downstream and 2 Gb/s of data upstream using a continuous-wave laser and a reflective semiconductor optical amplifier.

This paper presents a long-reach orthogonal frequency division multiplexing wavelength division multiplexing passive optical network (OFDM WDM-PON), a system capable of delivering 100  Gb/s of data downstream and 2  Gb/s of data upstream on a single wavelength. The optical sources for downstream data and upstream data are a continuous-wave laser at a central office and a reflective semiconductor optical amplifier (RSOA) at each optical network unit.

Analysis of Full Volterra and Sparse Volterra Nonlinear Equalization for Downlink LTE System

In this work, we propose Full Volterra and Sparse Volterra channels equalization algorithms for downlink LTE system. For estimation purpose, the LTE standard provides known data as pilot symbols and exploits them through a coherent detection to improve system performance. The references symbols location is similar to diamond pattern through time and frequency domain. Our goal is to show how to use the Full Volterra and Sparse Volterra equalizers over frequency domain in order to mitigate linear and nonlinear effects introduced by power amplifier and multipath channel. Downlink LTE Performances System in term of BLER, EVM (%) and Throughput versus SNR are presented and discussed. Then we compare our results with basic RLS equalizer curves. Moreover, it is shown that the Full Volterra and Sparse Volterra models can significantly reduce interferences and nonlinear effects and consequently improve the performances of LTE Downlink System.

Analysis of Wiener - Hammerstein equalizer for optical OFDM modem

We propose a non Linear Wiener Hammerstein channel equalization algorithm for coherent optical OFDM system. The proposed equalization method compensates the channel non linearities. Simulations for the proposed non linear equalizer are conducted using a training sequence method to determine optimal performance through a comparative analysis. When compared to the un-equalized signals results show an improvement when using the Wiener Hammerstein equalizer. Moreover, it is shown that Wiener Hammerstein algorithm showed to be significantly beneficial for coherent optical OFDM systems. The performances of all different schemes were compared with respect to bit error rate, transmission distance, optical signal to noise ratio, power launch and error vector magnitude.

A novel support vector machine robust model based electrical equaliser for coherent optical orthogonal frequency division multiplexing systems

Classifiers, such as artificial neural networks non-linear equaliser (ANN-NLE), Wiener–Hammerstein non-linear equaliser, Volterra non-linear equaliser (Volterra-NLE) and support vector machine non-linear equaliser (SVM-NLE), can play a significant role in compensating non-linear imperfections in the optical communications context. Using classifiers to mitigate the non-linear effects in coherent optical orthogonal frequency division multiplexing (CO-OFDM) systems is an interesting idea to be investigated. In this study, a novel support vector machine robust version, specifically adapted to a 100 Gb/s CO-OFDM data structure for long haul distance, is proposed. Firstly, the authors demonstrate that SVM-NLE upgrades the system performance by about 10−1 in terms of bit-error rate compared to Volterra-NLE at optical signal-to-noise ratio equal to 14 dB. Then, they show that it can double the transmission distance up to 1600 km over single mode fibre channel. Furthermore, a performance comparison is performed using 16 quadrature amplitude modulation and 40 Gb/s bit rate for SVM-NLE, ANN-NLE and inverse Volterra series transfer function non-linear equaliser, respectively.

Nonlinearity mitigation of optical Fast-OFDM signals using a Wiener-Hammerstein electrical equalizer

In this paper, the principles of coherent optical Fast-OFDM and the modem design with the employment of a Wiener-Hammerstein equalizer (W-H/E) are described. Afterwards, we test 16QAM Fast-OFDM with W-H/E for up to 3500 km of transmission. Finally, we compare coherent optical Fast-OFDM with conventional CO-OFDM using W-H/E.

Adaptive Volterra Equalizer for optical OFDM modem

This paper addresses OFDM (orthogonal frequency division multiplexing) transmission over optical links with high spectral efficiency, i.e. by using high-order QAM-modulation schemes as a mapping method prior to the OFDM multicarrier representation. Here we address especially coherent optical OFDM modem in long distance which is affected by a nonlinear distortion caused by fiber nonlinearity as a major performance-limiting factor in advanced optical communication systems. We proposed a nonlinear electrical equalization scheme based on the Volterra model. Compared with other popular linear compensation technique such as the LMS (least Mean Square) and RLS (Recursive Least square), simulation results are presented to demonstrate the capability of a Volterra model based electrical equalizer used in a coherent optical orthogonal frequency division multiplexing system. It is shown that the Volterra model based equalizer can significantly reduce nonlinear distortion.

Non linearity equalization for coherent optical OFDM modem

We propose a Linear adaptive channel equalization using the recursive least-squares (RLS) algorithm for coherent optical OFDM system. The proposed equalization method adaptively compensates the channel non linearities. Simulations for the proposed adaptive equalizer are conducted using a training sequence method to determine optimal performance through a comparative analysis. When compared to the un-equalized signals results show an improvement when using the Adaptive Equalization (AE). Moreover, it is shown that AE using RLS algorithm showed to be significantly beneficial for coherent optical OFDM systems. The performances of all different schemes were compared with respect to bit error rate, transmission distance, optical signal to noise ratio, power launch and error vector magnitude.

Fiber non linearties mitigations with different Equalizers for optical OFDM modem

We propose in this paper a nonlinear electrical equalizations scheme based on the different equalizer for Coherent optical OFDM modem. Simulation results are presented to demonstrate the capability of these models to mitigate fiber non linearties.

Performance analysis of passive optical network systems based on the IM/DD OFDM modulation technique

Motivated by the robust immunity to interference as well as the higher spectrum efficiency, Orthogonal Frequency Division Multiplexing (OFDM) has been widely considered as one of the strongest contenders for high-speed Next- Generation Passive Optical Networks (NG-PONs), which satisfies the huge surge in demand for high-speed broadband services. In the other hand, OFDM systems suffer from a high Peak-to-Average Power Ratio (PAPR) at the transmitted signal resulting in signal degradation. The simplest method to deal with the PAPR problem consists in applying deliberate clipping to the transmitted signal which significantly reduces the requirement of the received optical power. In this paper, an analytical evaluation for the performance of an IM/DD optical OFDM system is shown, this is while accounting for clipping distortion and quantification noise caused by the limited bit resolution of DAC converter. Moreover, the paper demonstrates that applying digital signal restoration at the system receiver enables further improvements in the system performances in terms of enhanced effective Signal-to-Noise Ratio (SNR) and reduced optical power that is required to achieve specified Bit-Error-Rate (BER).

Cost-Effective OFDM WDM-PON system Delivering Downstream data 100Gbps and Upstream data 2 Gbps

This paper presents Long Reach Orthogonal frequency division multiplexing Wavelength Division Multiplexing Passive Optical Network (OFDM WDM-PON) system capable of delivering downstream 100 Gbit/s data and upstream 2 Gbit/s data on a single wavelength. The optical source for downstream data and upstream data is Continous wave Laser at central office and reflective semiconductor optical amplifier (RSOA) at each optical network unit. We use two RSOAs at each optical network unit for the 2-Gb/s upstream transmission. We extend the maximum reach of this OFDM WDM PON to be 50 km by using Raman amplifiers at the RN. The hybrid amplifier is designed to enhance the signal power and compensated the fiber dispersion over a wide wavelength range. The combination of 45 km single mode fiber and 5 km dispersion compensated fiber (DCF) is used for transmission of upstream data to improve uplink performance. This research focuses on the implementation and performance analysis of high data rate coherent optical OFDM WDM PON for long-haul transmission. OptiSystem-12 simulation tool is fully used to design and implement the system. The performance of the system is studied and analyzed system in terms of Bit-Error-Rate (BER), the effect of the transmission distance on the constellation diagram, and the relation of BER and OSNR with regard to transmitted input power.