Ahlam Damati

Wavelet transformation method to allocate the OFDM signals peaks

This work makes use of the entropy in order to propose a wavelet transformation algorithm to detect the odd peaks. Furthermore, this algorithm has been used to enhance the Orthogonal Frequency Division Multiplexing (OFDM) system performance based on combatting the peak-to-average power ratio (PAPR) problem. Three main stages are used to fulfill the process requirements; OFDM signal transformation based on the wavelet structure, thresholding process based on a predetermined criterion, and the filtration stage based on the moving filter. The proposed algorithm performance has been checked and validated not just numerically but also by a MATLAB conducted simulation. Furthermore, to check the simulation results, a comparison has been made to the literature; and shows promising results under the same bandwidth occupancy and systems limitations.

Improving the MIMO-OFDM systems performance-based GA

This paper proposes a new peak-to-average power ratio (PAPR) reduction method for a multiple-input multipleoutput (MIMO)-orthogonal frequency division multiplexing (OFDM) systems based on a genetic algorithm (GA). In this proposition we have combined a previously published work with the genetic algorithm to enhance both of the PAPR reduction ratios and computational load that are found in the literature. During this work, there was a comparison that has been stated among three techniques that were proposed to overcome the PAPR drawback; original Partial Transmit Sequence (PTS) technique, previously published work based on the linear coding and a modified version that combines the linear coding with GA. Finally, a range of simulation results are provided to demonstrate the superiority of the proposed scheme.

Optical OFDM QoS improvement based on Wavelet packet transform

An optical Orthogonal Frequency Division Multiplexing (OFDM) has been proposed based on Wavelet packet transform (WF-O-FDM). In this paper, a performance investigation has been made to check the validity of the proposed work. This investigation has been made based on two crucial factors, BER and the Complementary Cumulative Distribution Function (CCDF). A MATLAB based simulation has been taking over to examine this performance and to compare it with conventional OFDM that is based on FFT. The extracted results show that the WF-O-FDM depicts an improvement of the BER for the same optical bandwidth occupancy, while the Peak to Average Power Ratio (PAPR) values has been reduced for about 85% compared with the conventional one.

Enhancing the MIMO-OFDM Radar systems performance using GA

This paper proposes a new peak-to-average power ratio (PAPR) reduction method for a multiple-input multiple-output (MIMO)-orthogonal frequency division multiplexing (OFDM) systems based on a genetic algorithm (GA). It has been introduced to be compatible with Radar systems, where the GA was used to optimize the MIMO-OFDM symbols in such way that could improve the systems performance. During this work, there was a comparison that has been stated among three systems; original radar system, radar system-based MIMO-OFDM and radar system-based MIMO-OFDM uses GA. Finally, a range of simulation results are provided to demonstrate the superiority of the proposed scheme, since it is showed an enhancement in the coverage distance besides reducing the PAPR effects.

PAPR effect remedy in OFDM-based wireless systems

An enhancement proposition for a Terrestrial Digital Video Broadcasting (DVB-T) systems is discussed in this work. DVB-T physical layer uses a powerful technique namely Orthogonal Frequency Division Multiplexing (OFDM) technique, which has been used to combat the channel’s effect. However, it has a major drawback that degrades its efficiency; namely Peak-to-Average Power Ratio (PAPR). Two criteria have been used for this purpose; BER curves and CCDF curves in order to distinguish the powerfulness of those propositions in reducing the PAPR effect. In fact, a powerful special averaging technique results are compared to previously published propositions, namely based on wavelet transformations and the one that is based on the pulse width modulation. A mathematical model has been drawn in order to check both of the CCDF and the BER curves, and simulated at same channel limitations and specifications. The proposition gives extra 35% noise immunity over our previously published work that is based on entropy wavelet, and an enhancement of over 25% from the CCDF point of view in combatting the PAPR. Furthermore, a complexity reduction has been attained by decreasing the side information transmission in compared with the work in the literature.

OFDM systems performance enhancement

In this work a comparison among different proposed algorithms has been done to check the performance improvements for current wireless technologies. Orthogonal Frequency Division Multiplexing (OFDM) technique is one of the main techniques that are uses to enhance the quality of service (QoS) for beyond third generation (B3G) systems. This is in order to meet the rapidly increased of multimedia users demand. This comparison includes three previous propositions that were made to enhance the OFDM performance; work based on linear coding techniques, work based on wavelet transform and work based on PWM. All these propositions have been made to combat the effect of high Peak-to-Average Power Ratio (PAPR).