Ashraf Yahia Hassan

Ashraf Yahia Hassan
Benha University · Department of Electrical Engineering (Benha)

Professor

About

33
Publications
2,966
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
94
Citations
Additional affiliations
December 2009 - December 2015
Benha University
Position
  • Lecturer

Publications

Publications (33)
Article
Full-text available
Radio Frequency (RF) energy harvesting has been used to power wireless and low-powered devices. However, RF energy harvesting has limitations in terms of the amount of power that can be collected based on signal availability. Hence, energy prediction is essential to improve energy harvesting circuits' performance. Previous research has mainly focus...
Conference Paper
Radio Frequency (RF) energy harvesting has been employed to power wireless devices. Nevertheless, RF energy harvesting encounters restrictions regarding the quantity of power it can harvest depending on signal accessibility. As a result, accurately predicting energy levels becomes crucial for enhancing the performance of energy harvesting cir...
Article
Full-text available
In this study, a high-gain wideband circularly polarized (CP) printed monopole antenna for wireless local-area network (WLAN), worldwide interoperability for microwave access or WiMAX, C-band, and multiple input, multiple output (MIMO) applications was proposed and demonstrated. The proposed antenna structure has an octal-shaped monopole antenna ti...
Article
Full-text available
This paper presents a novel approach to digital signature by integrating the ElGamal or Schnorr digital signature algorithms, chaotic systems, and scanning techniques. Briefly, ZZBCRP is a zigzag transformation that is used firstly to construct a permuted transaction, which technique starts from any random position and intersects in both directions...
Article
Full-text available
Accurate PV system simulators are implemented with expensive software platforms using paid irradiance data. The main purpose of this paper is to develop and validate a PV system simulator, beginning with a solar cell parameter extraction model, then test and validate long-term Irradiance data using free online source (Typical Meteorological Year TM...
Article
Full-text available
This paper aims to improve SHA-512 security without increasing complexity; therefore, we focused on hash functions depending on DNA sequences and chaotic maps. After analysis of 45 various chaotic map types, only 5 types are selected in this proposal—namely, improved logistic, cosine logistic map, logistic sine system, tent sine system, and hybrid....
Article
Full-text available
A time-diversity system is implemented in this work using a time-diversity encoder. The diversity encoder uses an orthogonal matrix to map vectors of $N$ modulated symbols to vectors of $N$ diversity symbols. Each modulated symbol is implicitly transmitted $N$ times in $N$ successive periods when the $N$ diversity symbols are transmitted....
Article
Full-text available
Optimum usage of the existing frequency spectrum is a major requirement due to the large increase in the number of subscribers at the same frequency. The cognitive radio scheme has become an important application used to optimize spectrum utilization, detects spectrum bands that are not occupied by primary users to create communication links betwee...
Article
Full-text available
In this paper, a new approach is proposed for implementing an adaptive decision feedback equalizer (ADFE) for the 5G channel. The proposed equalizer works in two phases. In the first phase, a least-squares (LS) algorithm with a variable-length training sequence is used to estimate the coefficients of the channel and the equalizer. In the second pha...
Article
Zero-Forcing (ZF) detector is used in Space-Division Multiplexing (SDM) receiver to remove interference among the received symbols. Previous works showed that the power of channel noise is enhanced in the output of the ZF detector. They recommend using the ZF detector when the received Signal-to-Noise Ratio (SNR) is high. This work proves that the...
Article
In this work, a new time diversity scheme is proposed to achieve time diversity in flat fading channels without affecting the data transmission rate. The conventional time diversity system reduces the transmission rate of the modulated symbols by a factor equal to the time diversity order. However, in the proposed time diversity system, any require...
Article
Full-text available
In this work, a diversity encoder maps vectors of N modulated symbols to vectors of N diversity symbols using an orthogonal matrix. Each modulated symbol appears in N diversity symbols. An Orthogonal-Frequency-Division-Multiplexing (OFDM) modulator converts the diversity vectors to OFDM symbols. The number of subcarriers in the OFDM symbol equals N...
Article
Full-text available
This paper proposes a new time–space diversity scheme for data transmission through flat fading channels. Extended pulses are used to shape the modulated symbols at different time slots. The proposed transmitter does not change the transmission rate of the modulated symbols after the shaping process. One transmitting antenna is used to transmit the...
Article
Multiuser systems suffer from multiple access interference (MAI) due to the correlations between users signature codes. The decorrelator detector uses the inverse correlation matrix of the signature codes to eliminate the MAI. The major disadvantage of the decorrelator detector is the enhancement of the noise power at its outputs as mentioned in ma...
Article
Full-text available
Inter-symbol interference (ISI) causes many errors in modulated symbols, when they are transmitted through band-limited channels. According to the multipath delay profile of the channel, the modulated symbol may disperse over more than one symbol period casing interferences among the received symbols. In this paper, the ISI signal is not considered...
Article
Full-text available
High-Speed Orthogonal-Frequency-Division-Multiplexing (HS-OFDM) is an OFDM system with high OFDM symbol rate. In HS-OFDM system, the symbol period is comparable with the multipath delay-spread of the channel. No cyclic-prefix is used with HS-OFDM to increase the bandwidth efficiency. HS-OFDM suffers from Inter-Symbol Interference (ISI) and Inter-Ca...
Article
Full-text available
Orthogonal-frequency-division-multiplexing (OFDM) systems suffer from Inter-carrier interference (ICI) when the orthogonality between subcarriers is lost. The orthogonality between subcarriers is lost due to two factors. The first is the Doppler-frequency shift in the subcarriers due to the relative motion between the transmitter and receiver. The...
Article
Full-text available
This paper proposes a new technique to increase the symbol rate in Quadrature Amplitude Modulation (QAM) using a new set of orthonormal functions. The proposed technique increases the rate of QAM symbols without increasing the bandwidth of the modulated signal or increasing the modulation order of the QAM symbol. The set of orthonormal functions co...
Article
This paper proposes a transmit-diversity system using a pair of orthogonal pulses. The system uses a set of orthonormal-basic functions, which contains four shaped-sinusoidal pulses with the same frequency. The first two elements in the set are shaped sine and cosine pulses. The second two elements are the same sine and cosine pulses but they are s...
Conference Paper
This paper introduces a new way to increase the transmission rate of data in Orthogonal-Frequency-Division-Multiplexing (OFDM) system. The data rate is doubled by doubling the number of the subcarriers in the OFDM signal. The bandwidth of the OFDM signal and the OFDM-symbol rate are not changed. Complex Exponential Subcarriers (CESs) are used inste...
Article
This paper proposes a new modulation technique that doubles the transmission rate of data symbols in digitally modulated systems. The rate is doubled without any changes in the used signal constellation or the modulated signal bandwidth. The proposal doubles the transmission rate by using Complex-Exponential-Basic-Functions (CEBFs) instead of Real-...
Article
Time diversity is achieved in direct sequence spread spectrum by receiving different faded delayed copies of the transmitted symbols from different uncorrelated channel paths when the transmission signal bandwidth is greater than the coherence bandwidth of the channel. In this paper, a new time diversity scheme is proposed for spread spectrum syste...
Article
In wireless channel the noise has a zero mean. This channel property can be used in the enhancement of the noise performance in the digital receivers by oversampling the received signal and calculating the decision variable based on the time average of more than one sample of the received signal. The averaging process will reduce the effect of the...
Article
Quadrature Amplitude Modulation (QAM) system with high data rate suffers from Inter-Symbol-Interference (ISI) in frequency-selective wireless channel. To reduce this ISI signal, Decision Feedback Equalizer (DFE) is used. When the channel impulse response is time varying, the channel's coefficients need to be adaptively estimated. Adaptive implement...
Conference Paper
In linear time invariant channel model, the systems that are designed based on CDMA are suffering from multiple access interference (MAI) and noise problems. In time varying channel model, the CDMA systems suffer from complex time varying channel's gains plus MAI and noise. A lot of CDMA detectors are designed to overcome the MAI problem. But these...
Conference Paper
Code Division Multiple Access (CDMA) is a widely used multiple access method in a lot of nowadays vital applications. The systems that are designed based on CDMA are suffering from multiple access interference (MAI) problem. A lot of CDMA detectors are designed to overcome the (MAI) problem. But as the capability of CDMA detector in (MAI) cancellat...
Conference Paper
Code Division Multiple Access (CDMA) is a widely used multiple access method in a lot of nowadays vital applications. The systems that are designed based on CDMA are suffering from multiple access interference (MAI) problem. A lot of CDMA detectors are designed to overcome the (MAI) problem. But as the capability of CDMA detector in (MAI) cancellat...
Article
Full-text available
Code Division Multiple Access (CDMA) is a widely used multiple access method in a lot of nowadays vital applications. The systems that are designed based on CDMA are suffering from multiple access interference (MAI) problem. A lot of CDMA detectors are designed to overcome the (MAI) problem. But as the capability of CDMA detector in (MAI) cancellat...
Article
The systems that are designed based on CDMA are suffering from a multiple access interference problem. The decorrelator CDMA detector is a linear detector that can cancel the MAI but with channel noise enhancement. The complexity of the decorrelator is a linear function in the number of the system's users. In this research, a new detector is propos...

Network

Cited By