arXiv subjects

Ehab Salahat

Publications and source records attributed to Ehab Salahat.

10 recordsLinked to original sources

arXiv2017

Error Rates Analysis of MIMO Space-Time Block Codes in Generalized Shadowed Fading Channels

This paper introduces a new and unified bit error rates performance analysis of space-time block codes (STBC) deployed in wireless systems with spatial diversity in generalized shadowed fading and noise scenarios. Specifically, we derive a simple and a very accurate approximate expressions for the average error rates of coherent modulation schemes in generalized $η-μ$ and $κ-μ$ shadowed fading channels with multiple input multiple output (MIMO) systems. The noise in the network is assumed to be modeled using the additive white generalized Gaussian noise (AWGGN), which encompasses the classical Laplacian and the Gaussian noise environments as special cases. The derived results obviate the need to re-derive the error rates for MIMO STBC systems under many multipath fading and noise conditions while avoiding any special functions with high computational complexity. Published results from the literature, as well as numerical evaluations, corroborate the accuracy of our derived generalized expressions.

cs.IT↗

arXiv2017

Exploring Symmetry in Wireless Propagation Channels

Wireless communications literature is very rich with empirical studies and measurement campaigns that study the nature of the wireless propagation channel. However, despite their undoubted usefulness, many of these studies have omitted a fundamental yet key feature of the physical signal propagation, that is, wireless propagation asymmetry. This feature does not agree with the electromagnetic reciprocity theorem, and the many research papers that adopt wireless channel symmetry, and hence rendering their modeling, unexpectedly, inaccurate. Besides, asymmetry is unquestionably an important characteristic of wireless channels, which needs to be accurately characterized for vehicular/mobile communications, 5G networks, and associated applications such as indoor/outdoor localization. This paper presents a modest and a preliminary study that reports potential causes of propagation asymmetry. Measurements conducted on Khalifa University campus in UAE show that wireless channels are symmetric in the absence of symmetry impairments. Therefore, care should be taken when considering some practical wireless propagation scenarios. Key conclusions and recommendation are summarized. We believe that this study will be inspiring for the academic community and will trigger further investigations within wireless propagation assumptions.

cs.IT↗

arXiv2017

Investigation of Wireless Channel Asymmetry in Indoor Environments

Asymmetry is unquestionably an important characteristic of the wireless propagation channel, which needs to be accurately modeled for wireless and mobile communications, 5G networks, and associated applications such as indoor/outdoor localization. This paper reports on the potential causes of propagation asymmetry. Practical channel measurements at Khalifa University premises proved that wireless channels are asymmetric in realistic scenarios. Some important conclusions and recommendation are also summarized.

cs.IT↗

arXiv2017

Recent Advances in Features Extraction and Description Algorithms: A Comprehensive Survey

Computer vision is one of the most active research fields in information technology today. Giving machines and robots the ability to see and comprehend the surrounding world at the speed of sight creates endless potential applications and opportunities. Feature detection and description algorithms can be indeed considered as the retina of the eyes of such machines and robots. However, these algorithms are typically computationally intensive, which prevents them from achieving the speed of sight real-time performance. In addition, they differ in their capabilities and some may favor and work better given a specific type of input compared to others. As such, it is essential to compactly report their pros and cons as well as their performances and recent advances. This paper is dedicated to provide a comprehensive overview on the state-of-the-art and recent advances in feature detection and description algorithms. Specifically, it starts by overviewing fundamental concepts. It then compares, reports and discusses their performance and capabilities. The Maximally Stable Extremal Regions algorithm and the Scale Invariant Feature Transform algorithms, being two of the best of their type, are selected to report their recent algorithmic derivatives.

cs.CV↗

arXiv2017

Unified Analytical Modeling of the Error Rates and the Ergodic Channel Capacity in $η$-$μ$ Generalized Fading Channels with Integer $μ$ and Maximal Ratio Combining Receiver

In this paper we introduce a novel performance analysis of the $η$-$μ$ generalized radio fading channels with integer value of the $μ$ fading parameter, i.e. with even number of multipath clusters. This fading model includes other fading models as special cases such as the Nakagami-m, the Hoyt, and the Rayleigh. We obtain novel unified and generic simple closed-form expressions for the average bit error rates and ergodic channel capacity in the additive white generalized Gaussian noise (AWGGN), which includes the additive Gaussian, the gamma, the Laplacian, and the impulsive noise as special cases. The receiver is assumed to be an L-branch maximal ratio combiner where we study the effect of having more deployed receiver antenna. Numerical evaluation as well as results from technical wireless literature validate the generality and the accuracy of the derived unified expressions under the studied test cases.

cs.IT↗

arXiv2017

Moment Generating Functions of Generalized Wireless Fading Channels and Applications in Wireless Communication Theory

In this paper, new exact and approximate moment generating functions (MGF) expression for generalized fading models are derived. Specifically, we consider the $η-λ-μ$, $α-μ$, $α-η-μ$, $α-λ-μ$, $α-κ-μ$, and $α-λ-η-μ$ generalized fading distributions to derive approximate MGF expressions. The new expressions are very accurate and, in contrast to earlier results in the literature, avoid any complicated special functions, e.g. the Meijer-$G$ and Fox $H$-functions. As such, the new MGF expressions allow easier and more efficient analytical manipulations, which also apply for their special cases such as the Rayleigh, Rice, and Nakagami-m fading. As an illustrative application, the average bit error rates for each of the fading models are evaluated using the new derived MGF expressions. The accuracy of the analytical results by using the numerically computed results as a basis of comparison as well as published results from the literature.

cs.IT↗

arXiv2017

Maximal Ratio Combining Diversity Analysis of Underwater Acoustic Communications Subject to $κ-μ$ Shadowed Fading Channels

In this paper, a novel unified analytical expression for average bit error rates (ABER) and average channel capacity (ACC) is presented for the $κ-μ$ shadowed fading model. This new shadowed fading model has shown to be suitable for underwater wireless channel modeling for the measurements conducted by the Naval Research Laboratory, and is not so well covered in the public literature. Deploying the Maximal Ratio Combining (MRC) receiver, a new simple analytical expression for the probability density function (PDF) of the receiver output signal to noise ratio is presented. Based on this new PDF, the novel unified ABER and ACC expression derived. To further generalize the error rate analysis, the additive white generalized Gaussian noise model is assumed that models the different noise environments. The new unified expression is accurate, simple and generic, and is suitable for MRC analysis in this generalized shadowed fading and noise environment. Numerical techniques and published results from the technical literature corroborate the generality and accuracy of our analysis under the different test scenarios.

cs.IT↗

arXiv2016

Unified Error Rates Analysis of MIMO Space-Time Block Codes over Generalized Shadowed κ-μ and η-μ Fading and AWGGN

This paper presents a novel unified performance analysis of Space-Time Block Codes (STBCs) operating in the Multiple Input Multiple Output (MIMO) network and subjected to generalized shadowed fading and noise scenarios. Specifically, we derive novel, simple and accurate average bit error rates (ABER) expressions for coherent modulation schemes in the generalized η-μ and shadowed κ-μ fading channels. The noise in the network is assumed to be modeled by the additive white generalized Gaussian noise (AWGGN), which encompasses the Laplacian and the Gaussian noise environments as special cases. The result obviates the need to re-derive the error rates for MIMO STBC systems under many multipath fading and noise models, while avoiding computationally-expensive expressions. Published results from the literature as well as numerical simulations corroborate the accuracy of our derived generalized expressions.

cs.IT↗

arXiv2016

On the Performance of DCSK MIMO Relay Cooperative Diversity in Nakagami-m and Generalized Gaussian Noise Scenarios

Chaotic Communications have drawn a great deal of attention to the wireless communication industry and research due to its limitless meritorious features, including excellent anti-fading and anti-intercept capabilities and jamming resistance exempli gratia. Differential Chaos Shift Keying (DCSK) is of particular interest due to its low-complexity and low-power and many attractive properties. However, most of the DCSK studies reported in the literature considered the additive white Gaussian noise environment in non-cooperative scenarios. Moreover, the analytical derivations and evaluation of the error rates and other performance metrics are generally left in an integral form and evaluated using numerical techniques. To circumvent on these issues, this work is dedicated to present a new approximate error rates analysis of multi-access multiple-input multiple-output dual-hop relaying DCSK cooperative diversity (DCSK-CD) in Nakagami-m fading channels (enclosing the Rayleigh fading as a particular case). Based on this approximation, closed-form expressions for the average error rates are derived for multiple relaying protocols, namely the error-free and the decode-and-forward relaying. Testing results validate the accuracy of the derived analytical expressions.

cs.IT↗

arXiv2016

A Novel Hybrid Fast Switching Adaptive No Delay Tanlock Loop Frequency Synthesizer

This paper presents a new fast switching hybrid frequency synthesizer with wide locking range. The hybrid synthesizer is based on the tanlock loop with no delay block (NDTL) and is capable of integer as well as fractional frequency division. The system maintains the in-lock state following the division process using an efficient adaptation mechanism. The fast switching and acquisition as well as the wide locking range and the robust jitter performance of the new hybrid NDTL synthesizer outperforms conventional time-delay tanlock loop (TDTL) synthesizer by orders of magnitude, making it attractive for synthesis even in Doppler environment. The performance of the hybrid synthesizer was evaluated under various conditions and the results demonstrate that it achieves the desired frequency division.

cs.IT↗