Mona Shokair - Academia.edu (original) (raw)

Papers by Mona Shokair

Mobile WiMAX is a broadband wireless solution that enables convergence of mobile and fixed broadb... more Mobile WiMAX is a broadband wireless solution that enables convergence of mobile and fixed broadband networks through a common wide area broadband radio access technology and flexible network architecture. It adopts Orthogonal Frequency Division Multiple Access (OFDMA) for improved multi-path performance in Non-Line-Of-Sight (NLOS) environments. Scalable OFDMA (SOFDMA) is introduced in the IEEE 802e[1]. WIMAX system uses one of different types of channel coding but The mandatory channel coding scheme is based on binary nonrecursive Convolutional Coding (CC). There are other several optional channel coding schemes such as block turbo codes, convolutional turbo codes, and low density parity check (LDPC). In this paper a comparison between the performance of WIMAX using turbo code and using convolutional product code (CPC) [2] is made. Also a combination between them had been done. The CPC gives good results at different SNR values compared to both the turbo system, and the combination...

2018 35th National Radio Science Conference (NRSC), 2018

This paper proposes cooperative Device to Device (D2D) communication which uses a cooperative rel... more This paper proposes cooperative Device to Device (D2D) communication which uses a cooperative relay technique; that used to reduce the interference; with conventional underlay D2D communication, where a relay is chosen from Cellular Users. Therefore, two proper methods for interference management and cancellation using the AAF strategy in D2D communication with Maximum Ratio Combining (MRC) will be suggested which are not clarified until now. From simulation results; we can conclude that by using a relay with a D2D channel in the presence of AWGN and flat fading, the BER will be decreased at low SNR levels. Moreover, D2D link throughput will be increased by 20%. Also comparison between the proposed technique and another one will be made, where the proposed reduce BER by 9 dB. Also, best location of the relay will be chosen. Moreover, the effect of changing D2D pairs number on the outage ratio links will be studied. It can be seen that when the D2D number equal to 20 pairs, the outage ratio will be reduced to 0.002.

2017 13th International Computer Engineering Conference (ICENCO), 2017

Cognitive radio is an efficient technology for spectrum utilization in wireless communication sys... more Cognitive radio is an efficient technology for spectrum utilization in wireless communication systems. Cooperative spectrum sensing is considered as a major technique in cognitive radio system because of being able to improve spectrum sensing and minimize probability of error in multi fading channels. In fact, clustering orders nodes into groups, clusters, to supply network better realization improvement. Also, clustering paradigm and collaborative spectrum sensing are gathered to reduce collision caused by reporting channel also improve sensing performance and reduce computations cost. A lot of algorithms of cooperative spectrum sensing had been discussed relayed on clustering scheme. In this paper, we provide an approach relayed on clustering scheme to reduce the total energy wasted by Cognitive Radio Network (CRN). clustering significance in CRN and its challenges are discussed. Categories of cluster based collaborative spectrum sensing are displayed moreover, the contribution of clustering in CRN is discussed.

China Communications, 2018

In this paper, the problem of communication security in an underlay wiretap cognitive radio netwo... more In this paper, the problem of communication security in an underlay wiretap cognitive radio network is addressed and statistically investigated. We rely on a simple dual-hop communication model of decode and forward relay assisted network. Regarding the interference from primary users, interference power and maximum transmit power constraints; this network is subjected to multiple eavesdropping attacks which employ a specific interception strategy. To confound this eavesdropping, proposed selection schemes are exploited that aim at maximizing the minimum of the dual secrecy rates in order to strengthen the physical layer security. Moreover, exact and asymptotic closed form expressions are derived for specific performance metrics over independent and identically distributed Rayleigh fading channels. At high signal to interference noise ratio (SINR), tangential system bounds are also derived and discussed. Monte Carlo simulation results emphasize our assumption. It is found out that a...

Cognitive radio is a promising te cognitive radio is how to increase sec paper, the effect of usi... more Cognitive radio is a promising te cognitive radio is how to increase sec paper, the effect of using multiple an to maximize the secondary throughp amplification factor. The analysis of value of the relay amplification facto antenna, the results show that using throughput and also improves the det

Wireless Personal Communications, 2018

In this paper, the benefit of distinguishable diversity order within a cooperative relay system i... more In this paper, the benefit of distinguishable diversity order within a cooperative relay system is exploited to overcome the problem of secure communication in an underlay wiretap cognitive radio network. This network is in a coexistence with a primary transceiver network and it is subjected to multiple eavesdropping attacks which employ a specific interception strategy. To improve the physical layer security, simple relay selection schemes will be proposed that aims at maximizing the minimum of the dual hop communication secrecy rates under primary network constraints. For Rayleigh fading channels, exact and asymptotic closed form expressions will be derived for the secondary system outage and secrecy rate. Furthermore, based on the network topology, tight inner and outer bounds will subsequently be derived on the system secrecy outage probability. By employing analytical and simulation results, the gain of the system diversity order is obviously investigated and emphasized.

Wireless Personal Communications, 2017

In the two published articles listed below, the affiliation of the first author of the second pap... more In the two published articles listed below, the affiliation of the first author of the second paper was correct, but the other authors' joint affiliation was incorrect. Their affiliation is correct in this erratum.

2016 12th International Computer Engineering Conference (ICENCO), 2016

Cooperative spectrum sensing assumes an essential part in cognitive radio network due to having t... more Cooperative spectrum sensing assumes an essential part in cognitive radio network due to having the capacity to enhance spectrum sensing performance and reduce probability of error in fading and shadowing channels. In fact, clustering scheme and cooperative spectrum sensing are combined to reduce Jostle of reporting channel, improve performance of sensing and reduce the computational cost. Many methods of cooperative spectrum sensing have been proposed based on clustering technique. In this paper, proposed approach will be suggested based on clustering to minimize the total power consumed by CRN in order to perform spectrum sensing, transmit decision to cluster head, and transmit the final decision to the fusion center. This is done by using multi objective genetic algorithm. Simulation results show that our proposed algorithm can achieve better energy gain which is less than conventional cluster based cooperative spectrum sensing scheme. Moreover, it increases performance of CRN.

International Journal of Computer Applications, 2016

In this paper, two systems will be introduced to improve the performance of Cooperative Cognitive... more In this paper, two systems will be introduced to improve the performance of Cooperative Cognitive Relay Network (CCRN). The first is Compress-and-Forward (CF) relay scheme based on joint source-channel coding for threeterminal classical relay network. Simulation results show that CF relay scheme gives remarkable performance gains over other cooperation strategies such as decode-and-forward and amplify-and-forward in this scenario where both source-relay and relay destination links have low signal-to-noise ratios. The second system is multi-hopping cooperative relaying with multi-antennas using decode and forward scheme. Using multi-hopping with multi-antennas techniques in CCRN gives a remarkable enhancement in the performance than using only one hop with single antenna system.

2016 33rd National Radio Science Conference (NRSC), 2016

Compressed sensing is an important topic in signal processing that provides the reconstruction of... more Compressed sensing is an important topic in signal processing that provides the reconstruction of a signal from a small number of linear measurements. The condition for compressed sensing is that the input signal must be sparse. Some signals are sparse in time domain and other signals must be converted to the frequency domain to be sparse. In this paper, sparse signal in the frequency domain will be assumed. When the signal is converted to sparse by using transform domain, it will cause the complex representation of both the sensing matrix and the input signal. To overcome this complexity, an efficient complex to real transformation technique is proposed to enhance the system performance. Furthermore, the sparse signal is recovered in less time and minimum error. Also, the signal to error ratio from the recovery process is increased. The proposed algorithm removes the imaginary parts and doubles the size of both the sensing matrix and the sparse signal by separating the real and complex variables to remove complexity.

Circuits and Systems: An International Journal, 2015

Primary User Emulation Attack (PUEA) is one of the major threats to the spectrum sensing in cogni... more Primary User Emulation Attack (PUEA) is one of the major threats to the spectrum sensing in cognitive radio networks. This paper studies the PUEA using energy detection that is based on the energy of the received signal. It discusses the impact of increasing the number of attackers on the performance of secondary user. Moreover, studying how the malicious user can emulate the Primary User (PU) signal is made. This is the first analytical method to study PUEA under a different number of attackers. The detection of the PUEA increases with increasing the number of attackers and decreases when changing the channel from lognormal to Rayleigh fading.

Journal of Theoretical and Applied Information Technology

In this paper, the diversity reception with correlated Rayleigh fading signals will be investigat... more In this paper, the diversity reception with correlated Rayleigh fading signals will be investigated. Results will be evaluated by converting two correlated Rayleigh fading signals into another two independent Rayleigh fading signals using transformation matrix. These results show that Optimum transformation matrix F=1 is better than F = 2 / 2 which is the elements of the optimum transformation matrix which convert two correlated Rayleigh fading signals into another two independent Rayleigh fading signals. Analysis of the system over Rayleigh fading will be made further, the BER performance will be investigated under BPSK modulation.

The WiMax technology based on air interface standard 802-16 wireless MAN is configured in the sam... more The WiMax technology based on air interface standard 802-16 wireless MAN is configured in the same way as a traditional cellular network with base stations using point to multipoint architecture to drive a service over a radius up to several kilometers. The range and the non line of sight (NLOS) ability of WiMax make the system very attractive for users,

Lecture Notes in Computer Science, 2010

With the rapid expand of wireless digital communications, demand for wireless systems that are re... more With the rapid expand of wireless digital communications, demand for wireless systems that are reliable and have a high spectral efficiency have increased too. Orthogonal Frequency Division Multiplexing (OFDM) has been recognized for its good performance to achieve high data rates. Fast Fourier Transforms (FFT) has been used to produce the orthogonal sub-carriers. Due to the drawbacks of OFDM-FFT based

Advanced Transmission Techniques in WiMAX, 2012

The type of proposed product code described in this chapter is called modified Convolutional Prod... more The type of proposed product code described in this chapter is called modified Convolutional Product Codes (CPC), considered as a different type of normal CPC [8]. The normal CPC depends on recursive systematic convolutional encoder, whereas the modified version of CPC will basically depend on non-recursive non-systematic convolutional encoder. www.intechopen.com Advanced Transmission Techniques in WiMAX 266 WiMAX system is a wireless communication system. It suffers from having a high Bit Error Rate (BER) at low Signal to Noise Ratio (SNR). Using modified version of CPC for WiMAX system reduces the BER at low SNR. Also using the modified version of CPC with WiMAX decreases the number of stages of its physical layer as described later.

Progress In Electromagnetics Research B, 2008

In this paper, a Medium Access Control (MAC) protocol is proposed to investigate Quality of Servi... more In this paper, a Medium Access Control (MAC) protocol is proposed to investigate Quality of Service (QoS) for multimedia traffic transmitted over Ultra Wide-Band (UWB) networks and increase the system capacity. This enhancement comes from using Wise Algorithm for Link Admission Control (WALAC) which has three suggested versions. The QoS of multimedia transmission is determined in terms of average delay, admission ratio, loss probability, utilization, and the network capacity. In addition, a new parameter is aroused for the network performance. Comparisons between the IEEE 802.15.3a protocol and the proposed one are done. The proposed protocol shows better results in both sparse and dense networks for real time traffic transmission.

2011 28th National Radio Science Conference (NRSC), 2011

Abstract Recently, cognitive radio (CR) access has received much attention to overcome spectrum s... more Abstract Recently, cognitive radio (CR) access has received much attention to overcome spectrum scarcity problem. Spectrum sensing methods are often used for finding free channels to be used by CR. In this paper, one of spectrum sensing method will be investigated. This method is cooperative spectrum sensing which is based on energy detection in CR networks in order to overcome fading, noise and shadowing effects on individual CR user and increase the reliability and efficiency of spectrum sensing. The ...

Wireless Personal Communications, 2015

Cognitive radio (CR) system is able to exploit the bands allocated to licensed or primary users w... more Cognitive radio (CR) system is able to exploit the bands allocated to licensed or primary users when they are not being used. Spectrum sensing is a key element of a working CR system. In this paper, enhanced algorithms are proposed for semi-blind spectrum sensing in CR networks using fourth-order statistics of the received primary user's signal. The proposed statistic will have a value equal or close to 3 when only Gaussian noise samples exist in the received signal. This estimate is used to differentiate between the presence or absence of the primary user by comparing with a predefined threshold. Using the Neyman-Pearson criterion, an optimized threshold is established and an analytical expression for the upper bound on the average probability of miss-detection (P m,avg) is also derived. The proposed algorithm clearly outperforms the energy detection (ED) method over the low-SNR range of −15 to 12 dB. For P m,avg = 10 −2 , e.g., the proposed scheme outperforms the ED method by 1.5 dB for the case of a single user. Moreover, the proposed algorithm has been extended to the cooperative spectrum sensing model. Simulation results show that the proposed scheme significantly outperforms the ED method in cooperative spectrum sensing scenarios. Keywords Cognitive radio (CR) • Spectrum sensing • Fourth-order statistics 1 Introduction Spectrum underutilization problem has been confirmed lately by the Federal Communications Commission (FCC) based on field measurements [1]. Consequently, due to the ever-growing

Progress In Electromagnetics Research C, 2008

Peak to Average Power Ratio (PAPR) is one of the serious problems in any wireless communication s... more Peak to Average Power Ratio (PAPR) is one of the serious problems in any wireless communication system using multi carrier modulation technique like OFDM, which reduces the efficiency of the transmit high power amplifier. In this paper, proposed scheme will be introduced that combine interleaving method with peak windowing. Simulation results show that our technique simultaneously decrease Bit Error Rate (BER), reduce the PAPR by 3.5 dB and improve outof-band radiation, in presence of nonlinear power amplifier model.