Liqaa AbdulSattar AL-Hashemi

Bio: Liqaa AbdulSattar AL-Hashemi is an academic researcher from University of Basrah. The author has contributed to research in topics: Orthogonal frequency-division multiplexing & Quadrature amplitude modulation. The author has an hindex of 1, co-authored 2 publications receiving 4 citations.

An ICI Reduction Based on PAPR Clipping in Coherent Optical OFDM System

Abstract: The Inter-Carrier Interference (ICI) compensation for Coherent Optical Orthogonal Frequency Division Multiplexing (CO-OFDM) system has been studied in this paper. The purpose behind is to investigate the presence of ICI due to the impact of Laser Phase Noise (LPN) and Fiber Non-Linearity (FNL). Thereby, we propose a simple clipping scheme which represents an effective distortion algorithm to decrease the Peak to Average Power Ratio (PAPR) for 4QAM system. The method exhibits a significant process on ICI cancellation in CO-OFDM system. The OFDM signal is basically transmitted along 550km distance rated at 10Gbps single mode fiber for the coherent optical mode. The new findings show that the receiver sensitivity is highly improved below 10−3 FEC for laser power 5dBm; and archives about 1dBm to 2.4dBm when laser power becomes 8dBm at a typical clipping ratio of 0.6. In particular, the system exhibits a good performance over a 385km transmission distance in comparison to the conventional CO-OFDM. As a result, the proposed clipping shows that the system can enhance its the performance by reducing ICI in the CO-OFDM system; in addition to present a high robustness in BER metric against FNL by a clear reduction in PAPR.

An Effective Combining Transformer to RelieveFiber Nonlinearity in CO-OFDM System

Abstract: This paper mainly concerns on reducing the impact of chromatic dispersion (CD) and the nonlinear(NL) impairments in coherent optical orthogonal frequency division multiplexing (CO-OFDM) system. In effect, the system suffers from a severe problem due to a high peak to average power ratio (PAPR); and this consequently degrades the system performance. In this paper, a new method is proposed to mitigate the PAPR problem and thereby reduce the impact of nonlinearity on the performance of the CO-OFDM system with quadrature amplitude modulation QAM mapping. The recommended new technique is based on combining two effective ways of clipping method integrated with the L2-by3 method. The simulation results indicate that the proposed method was effectively able to improve system performance by enhancing system performance via bit error rate (BER), quality factor (QF), error vector magnitude (EVM) beside the Optical Signal-to-Noise Ratio (OSNR) without the need to add any digital processing at the receiver; and eventually decrease the receiver complexity. The proposed method reduced the peak to average power ratio (PAPR) about 3.8 dB and helped to increase transmission distance by approximately 200 km.

OFDM for Optical Communications

Abstract: Orthogonal frequency division multiplexing (OFDM) is a modulation technique which is now used in most new and emerging broadband wired and wireless communication systems because it is an effective solution to intersymbol interference caused by a dispersive channel. Very recently a number of researchers have shown that OFDM is also a promising technology for optical communications. This paper gives a tutorial overview of OFDM highlighting the aspects that are likely to be important in optical applications. To achieve good performance in optical systems OFDM must be adapted in various ways. The constraints imposed by single mode optical fiber, multimode optical fiber and optical wireless are discussed and the new forms of optical OFDM which have been developed are outlined. The main drawbacks of OFDM are its high peak to average power ratio and its sensitivity to phase noise and frequency offset. The impairments that these cause are described and their implications for optical systems discussed.

Two-dimensions asymmetrically clipped optical orthogonal frequency division multiplexing for screen to a camera communications system

Abstract: Orthogonal frequency division multiplexing (OFDM) of the optical communication system is a known approach for light fidelity and the screen-to-a-camera (S2C) communication system is an innovative implementation for optical camera communication (OCC). In This paper, two dimensional (2D) asymmetrically clipping optical (ACO) OFDM for the S2C model can be obtained which develops a single screen display, consisting of several cells, for a data rate of up to 100 kb/s. This paper contains an innovative system design focused on validation of implementation and theoretical study. The source distribution of the ACO OFDM system has been implemented using LAB VIEW software. The performance of the suggested model was verified through numerical assessment techniques, as it was checked that within the transmission distance of 4.5 m and the field of view of 30 $$^\circ$$ overall bit error rate (BER) of 10−6 and signal to noise ratio (SNR) 18 dB is achieved. Under the existing IEEE 802.15.7 m standard, the overall results of the S2C OFDM system are being evaluated by comparing them to the 2D OFDM OCC system to illustrate the efficiency of the proposed scheme.