Bechir Nsiri

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.

Analysis of full volterra nonlinear equalizer for downlink LTE system

In this work, we propose a Full Volterra channel equalization for downlink LTE system. For estimation purpose, the LTE standard provides known data as pilots symbols and exploits them through a coherent detection to improve system performance. These drivers are placed in a hybrid way to cover up both time and frequency domain. Our aim is to precise how to adapt the Full Volterra technique to the LTE standard in order to compensate linear and nonlinear effects introduced by power amplifier and multipath channel. We present the comportment of Full Volterra equalizer in term of BLER, EVM (%) and Throughput versus SNR. Then we compare our results with basic RLSequalizercurves. Moreover, it is shown that the Full Volterra model can significantly reduce interferences and nonlinear effects and consequently improves the performances of LTE Downlink System.

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.

Analysis of Wiener-Hammerstein equalizer for downlink LTE system

We propose a Wiener-Hammerstein (W-H) channel estimation algorithm for Long-Term Evolution (LTE) systems. The LTE standard provides known data as pilot symbols and exploits them through coherent detection to improve system performance. These drivers are placed in a hybrid way to cover up both time and frequency domain. Our aim is to adapt the W-H equalizer (W-H/E) to LTE standard for compensation of both linear and nonlinear effects induced by power amplifiers and multipath channels. We evaluate the performance of the W-H/E for a Downlink LTE system in terms of BLER, EVM and Throughput versus SNR. Afterwards, we compare the results with a traditional Least-Mean Square (LMS) equalizer. It is shown that W-H/E can significantly reduce both linear and nonlinear distortions compared to LMS and improve LTE Downlink system performance.

Performance of window synchronisation in coherent optical ofdm system

In this paper we investigate the performances of a robust and efficient technique for frame/symbol timing synchronization in coherent optical OFDM. It uses a preamble consisting of only two training symbol with two identical parts to achieve reliable synchronization schemes. The performances of the timing offset estimator at correct and incorrect timing in coherent optical OFDM are compared in term of mean and variance of the timing offset, and finally, we study the influence of number of subcarriers and chromatic dispersion.

Study of the capacity of Optical Network On Chip based on MIMO (Multiple Input Multiple Output) system

When designing Optical Networks-On-Chip, designers have resorted to make dialogue between emitters (lasers) and receivers (photo-detectors) through a waveguide which is based mainly on optical routers called ?-router. In this paper, we propose a new method based on the Multiple Input Multiple Output concept, and we give a model of the channel propagation, then we study the influence of different parameters in the design of Optical Networks-On-Chip.