Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği

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  • Conference Object
    Role of Fractional Powers in Manuevering the Fractional Lower-Order Auto-Covariance of Symmetric Alpha-Stable Noise Signals
    (Institute of Electrical and Electronics Engineers Inc., 2019) Ahmed, Areeb; Savacı, Ferit Acar; Wahdan, Muath A.; Othman, Husam
    Since, Fractional Lower-Order Auto-Covariance (FLOAC) remains the only technique to quantify the similarity between alpha-stable (alpha-stable) signals, therefore, the effects of impulsiveness and skewness parameters has also been analyzed before for better generation and detection in various applications. This paper includes the detailed analysis of the FLOAC of symmetric alpha-stable (S alpha S) noise signals in order to observe the possible involvement of the associated fractional powers. The two associated fractional powers of FLOAC has been maneuvered in three possible ways to observe the probable trend of S alpha S noise signals in the presence and absence of Gaussian noise. The observation depicts that the fractional powers largely and solely affect the FLOAC when they are maneuvered collaboratively or even individually where the obtained results can be useful in improving many S alpha S noise signal processing techniques, especially, in the detection of S alpha S noise carrier signals in Random Communication Systems.
  • Conference Object
    Role of Fractional Powers in Maneuvering the Fractional Lower-Order Auto-Covariance of Skewed Alpha-Stable Signals in Gaussian Noise Environment
    (Institute of Electrical and Electronics Engineers Inc., 2019) Ahmed, Areeb; Savacı, Ferit Acar; Wahdan, Muath A.; Othman, Husam
    Since, alpha-stable noise signals similarity can only be gauged by Fractional Lower-Order Auto-Covariance (FLOAC), therefore, the role of impulsiveness and skewness parameters, in generation and detection of the skewed alpha-stable (Sk alpha S) noise signals, has been analyzed several times in the past. However, in this paper, a thorough analysis on the role of fractional powers in changing the FLOAC of Sk alpha S noise signals has been carried out. The two associated fractional powers of FLOAC has been maneuvered in three possible ways to observe the probable trend of Sk alpha S noise signals in the presence and absence of Gaussian noise. According to the observed results, the fractional powers largely and solely affect the FLOAC when they are manipulated collaboratively or even individually where the analyzed results can be handy in enhancing many Sk alpha S noise signal processing techniques, especially, in the detection of Sk alpha S noise carrier signals in Random Communication Systems.
  • Article
    Citation - WoS: 6
    Citation - Scopus: 6
    Structure and Performance Evaluation of Fractional Lower-Order Covariance Method in Alpha-Stable Noise Environments
    (Bentham Science Publishers B.V., 2019) Ahmed, Areeb; Savacı, Ferit Acar
    Background: All existing time delay estimation methods, i.e. correlation and covariance, depend on second or higher-order statistics which are inapplicable for the correlation of alpha-stable noise signals. Therefore, fractional lower order covariance is the most appropriate method to measure the similarity between the alpha-stable noise signals. Methods: In this paper, the effects of skewness and impulsiveness parameters of alpha-stable distributed noise on fractional lower order covariance method have been analyzed. Results: It has been found that auto-correlation, i.e. auto fractional lower order covariance, \ of non delayed alpha-stable noise signals follows a specific trend for specific ranges of impulsiveness and skewness parameters of alpha-stable distributed noise. The results also depict that, by maintaining the skewness and impulsiveness parameters of alpha-stable noise signals in a certain suggested range, better auto-correlation can be obtained between the transmitted and the received alpha-stable noise signals in the absence and presence of additive white Gaussian noise. Conclusion: The obtained results would improve signal processing in alpha-stable noise environment which is used extensively to model impulsive noise in many noise-based systems. Mainly, it would optimize the performance of random noise-based covert communication, i.e. random communication.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 2
    Blind Recognition of Alpha-Stable Random Carrier Signals by an Eavesdropper in Random Communication Systems
    (Institution of Engineering and Technology, 2019) Ahmed, Areeb; Savacı, Ferit Acar
    Invisibility of alpha-stable (alpha -stable) noise as carrier signals, in the presence of additive white Gaussian noise (AWGN) as channel noise, is a key factor to ensure covert transmission by employing random communication systems (RCSs). This study introduces a novel blind recognition method for an eavesdropper to detect the presence of real-valued symmetric and skewed alpha -stable random carrier signals in the presence of AWGN. The introduced method is based on the proposed random carrier signal recogniser (RCSR), which consists of fractional lower-order auto-covariance block, threshold control block and the random carrier signal recognition indicator. The proposed RCSR first detects the possible presence of alpha -stable random carrier signals and then recognises the impulsiveness and skewness parameters, exploited by the transmitter and the intended receiver, to extract covertly conveyed binary information. However, the determined covert range can be adopted to perform secure transmission by RCSs. The simulation results reflect the simplicity of the proposed method as it is capable of performing effectively in real time by utilising extremely less number of observed samples.
  • Article
    Citation - WoS: 5
    Citation - Scopus: 5
    Inverse System Approach To Design Alpha-Stable Noise Driven Random Communication System
    (Institution of Engineering and Technology, 2020) Savacı, Ferit Acar; Ahmed, Areeb
    In the proposed random communication system (RCS), the alpha-stable (alpha-stable) noise as a random carrier drives the transmitter which is modelled by the linear dynamical system and the skewness parameter of the random carrier encodes the binary messages. By selecting the receiver as the inverse system of the transmitter, the output of the receiver is ensured to be alpha-stable noise whose skewness parameters are then estimated to decode the binary messages. The response of a linear system to an alpha-stable process is again alpha-stable process, however, the skewness parameters of the response differs from that of the input which can only be recovered at the output of the inverse system. Hence, estimation of skewness parameter by an eavesdropper, without using the inverse system, will not reveal the true binary messages while the intended receiver truly decodes the binary messages. The proposed inverse system based RCS provides efficient performance which is shown by comparing the bit error rate of the intended receiver and an eavesdropper where the enhancement in covertness is shown by evaluating the covertness values of the proposed RCS.
  • Article
    Citation - WoS: 5
    Citation - Scopus: 8
    Covert Electromagnetic Nanoscale Communication System in the Terahertz Channel
    (World Scientific Publishing, 2020) Ahmed, Areeb; Savacı, Ferit Acar
    In this paper, an electromagnetic nano random communication system (EM-nRCS) has been proposed which ensures covert communication in the terahertz (THz) band. In the proposed system, the skewed alpha-stable noise shift keying method has been used to transmit random noise signals (RNSs) from the nano-transmitter (NT) by utilizing single-walled/carbon nanotubes-based true random number generator (SWCNTs-TRNG) and a graphene-based nano-antenna. A line-of-sight THz transparency window between 0.1 THz and 0.5 THz in the THz channel with spreading loss, molecular absorption loss and molecular absorption noise has been considered. Due to the broadband nature of the RNSs, the proposed EM-nRCS provides efficient transmission by overcoming the high path loss and intense channel noise arising from random fluctuations in the THz band. Non-coherent nano-receiver (NR) consisting of the modified extreme value method (MEVM) estimator has been proposed to extract the hidden binary information in the received RNSs. The bit error rate performance shows that the proposed EM-nRCS ensures high performance and covertness for future EM nanoscale communication devices.
  • Article
    Citation - WoS: 9
    Citation - Scopus: 13
    Synchronisation of Alpha-Stable Levy Noisebased Random Communication System
    (Institution of Engineering and Technology, 2018) Ahmed, Areeb; Savacı, Ferit Acar
    In this study, the pilot-assisted synchronisation method for a random communication system (RCS) has been proposed. The pilot symbol, which has alpha-stable distribution, has been used to establish synchronisation and to maintain covertness in the RCS. The introduced synchronisation block (SB) consists of fractional lower-order covariance-based correlators (FLOCCs), threshold detectors (TDs) and the synchronisation control block. To measure the performance of the proposed SB, the performance criterion, i.e. confidence ratio (CR), has been proposed. The reliability of the proposed SB can be enhanced by altering the CR and the achieved CR by using the FLOCCs and TDs in SB.
  • Conference Object
    Citation - WoS: 7
    Citation - Scopus: 12
    Measure of Covertness Based on the Imperfect Synchronization of an Eavesdropper in Random Communication Systems
    (Institute of Electrical and Electronics Engineers Inc., 2018) Ahmed, Areeb; Savacı, Ferit Acar
    Random Communication Systems (RCSs) given in the literature have assumed perfectly synchronized transmitter and receiver. However in this paper, instead of assuming perfect synchronization approach in RCSs, the effects of imperfect synchronization (IS) on Skewed Alpha-Stable Noise Shift Keying (SkaS-NSK) based RCS have been observed through simulations. The Bit Error Rate (BER) performance of the eavesdropper with respect to his synchronization error in SkaS-NSK based RCS, has been analyzed. An expression for the probability of an eavesdropper to decode the binary information (i.e., Eavesdropping Probability) in SkaS-NSK based RCS, has been derived. The criterion (i.e., Covertness Value) to measure the covertness level of RCSs has also been proposed. The BER performance of an eavesdropper provides an approximate margin of synchronization error if it can be overcome by an eavesdropper then he can achieve the decoding (i.e., eavesdropping) process.
  • Conference Object
    Citation - WoS: 2
    Citation - Scopus: 7
    On Optimizing Fractional Lower Order Covariance Based Synchronization Method for Random Communication Systems
    (Institute of Electrical and Electronics Engineers Inc., 2018) Ahmed, Areeb; Savacı, Ferit Acar
    Previously, the concept of Pilot Assisted Synchronization (PAS) and Fractional Lower Order Covariance (FLOC) has been incorporated together to synchronize alpha-stable noise based communication system which gave birth to Synchronized Random Communication Systems (SRCS). In this paper, an optimization criterion, i.e. FLOC Margin, has been proposed to improve the efficiency of the Fractional Lower Order Covariance based Correlators (FLOCCs) at the receiver side, hence, resulting in enhanced Bit Error Rate (BER) performance of SRCS. Since, the characteristic exponent and impulsiveness parameter are mainly responsible in generating and shaping up the required pilot sequence, therefore, the effects of these parameters on BER performance has also been observed by fluctuating them in their respective ranges. It has been shown that the proposed optimization criterion increases the BER efficiency of SRCS and also reveals the specific range of the characteristic exponent and impulsiveness parameter which can be exploited to achieve the optimum performance.
  • Article
    Citation - WoS: 14
    Citation - Scopus: 16
    Random Communication System Based on Skewed Alpha-Stable Levy Noise Shift Keying
    (World Scientific Publishing Co. Pte Ltd, 2017) Ahmed, Areeb; Savacı, Ferit Acar
    The digital communication system is based on the skewed alpha-stable (α-stable) noise sequence which is chosen as the random carrier to modulate the binary message at the transmitter side. Antipodal characteristic of the skew parameter beta (β) is exploited for decoding information at the receiver side to obtain a secure communication system. A fast estimator used in this paper is based on Modified Extreme Value Method (MEVM) to extract the binary message from the signal received through the Additive White Gaussian Noise (AWGN) channel. Our proposed receiver is achieving better bit error rate (BER) versus Mixed Signal to Noise Ratio (MSNR) than previously introduced receivers which are based on Sinc and Logarithmic estimators. MEVM estimator is indeed less complex compared to the Sinc and Logarithmic estimators and hence more fast. Additionally, the criterion to measure the security level of random communication system, which is based on α-stable noise sequence, has also been introduced.