Qadri Hamarsheh

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.

Enhancing the BER of MIMO-OFDM systems for Speaker verification

In this work a new algorithm has been proposed to improve the wireless systems that are compatible with the current new technologies. Therefore, Denoise Orthogonal Frequency Division Multiplexing (OFDM) symbols and Replace the high Peak-to-Average Power Ratio (PAPR); (DORP) has been modified. In DORP, wavelets techniques have been used to denoise the affected OFDM symbol by high PAPR values. After that and based on adaptive threshold method the local maxima and minima will be determined and replaced by the average of them and their surrounding neighbors. The algorithm mainly tackles and overcomes the effect of the high Peak-to-Average Power Ratio problem that is found in OFDM systems, MIMO-OFDM combination has been developed to meet the rapidly increment in the users demand such as the ubiquitous transmission, imposing new multimedia applications and wireless services. A system performance investigation process will be accomplished based on both of numerical method and MATLAB simulation. Moreover, a comparison has been made to check the validity of our proposition either with our previously published work or with the literature. Although, the achieved results show that the proposed work gives an improvement of the BER; an additional complexity has been added to transceivers structure. Moreover, and as a result to the comparison with the conventional systems, the bit error rate (BER) performance has been improved for the same bandwidth occupancy. As a validity process a comparison has been made with the current values found in the literature and we have achieved around 27% PAPR extra reduction. That is in addition to around 81% verification rate and noise immunity.

Unified matrix processor design for FCT-based filtering, convolution and correlation of signals

A new unified matrix processor for the main DSP discrete procedures: convolution, correlation functions and filtering of signals based on discrete cosine transform (DCT-II), is proposed and described. It is shown that these procedures can be computed using the same building blocks which give the processor universal computational structure property. The computational complexity analysis of the proposed processor shows that the FCT-based matrix processor for N-point convolution and correlation computing allows a reduction by 2N-3 real multiplications and N-2 real additions in comparison with other processors of the same class. The architecture of the processor supports the classic schema for computing DSP procedures: (Two DCT spectrums + product of cosine spectrums + IDCT transform). The proposed architectures employ simple Processor Elements (PE) that require real multiplications and additions.

Unified Matrix Processor Design for FCT-IV and FST-IV Hartley Based Transforms

A new unified fast shifted cosine and sine transform matrix processor based on fast Hartley transform is presented and described. It is also shown that the decimation-in-frequency (DIF) FCT-IV and FST-IV can be computed using the same building blocks which are used for computing decimation-in-time FCT-IV and FST-IV. A unified fast shifted cosine and sine transform matrix processor can be designed to compute either the DCT-IV or DST-IV

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).

Enhancing DVB-H BER based OFDM systems

Due to the need for enhancing the wireless systems performance, a new technique, and over the last decades, has been imposed to such systems, namely Orthogonal Frequency Division Multiplexing (OFDM). In order to overcome one of the main OFDM drawbacks a new proposal has been investigated, which could limit the usage of such system in the nonlinear devices. Peak-to-Average Power Ratio (PAPR) problem comes as a result of using Fast Fourier Transform (FFT) stage, where the input 2N signals and after the process could be added together in the same phase. In this algorithm some modifications have been made over a previously published, where the wavelet entropy understanding has been imposed to be the judge for the PAPR consideration. In the previous published work, when a wavelet technique was proposed to DeNoise OFDM symbols and Replace the high PAPR and named by DORP. This is attained by making use of an adaptive threshold to allocate the affected samples, which are amended according to the surrounding ones. In the Modified-DORP (M-DORP), the wavelet transform is used to reconstruct the affected OFDM symbol with PAPR based on their entropies. A MATLAB simulation has been made to verify and validate the numerical model that is derived to investigate the systems performance. Furthermore, the achieved results were compared to either our previously published work or to the work that found in the literature. However, the simulation results show BER systems improvement under the same systems’ conditions, an additional transceivers complexity has been added. This will leave a space for further improvement in future. Furthermore, the M-DORP gives a noise immunity and verification rate up to 85%.