Yazar "Yusuf, Marwan" seçeneğine göre listele

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    Controlled inter-carrier interference for physical layer security in OFDM systems
    (Institute of Electrical and Electronics Engineers Inc., 2016) Yusuf, Marwan; Arslan, Hüseyin
    Performance of OFDM is known to be very sensitive to frequency synchronization errors. By exploiting this feature, a novel technique is proposed to provide secure communication against eavesdropping. The technique is based on introducing self inter-carrier interference to pre-compensate the carrier offset only for the legitimate user. This pre-compensation process depends on both the channel and the local carrier offset of the legitimate user, hence provides another degree of freedom for secrecy. Under the assumption that eavesdropper experiences an uncorrelated channel, his performance is expected to be degraded. Also our approach converts the simple one-tap frequency domain channel equalization to a very complex receiver operation for the eavesdropper. Moreover, the power aspects of this technique are discussed. By setting a threshold in the pre-compensation stage, we provide an acceptable trade-off between the transmitted power and the error performance.
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    Cross MAC/PHY layer security design using ARQ with MRC and adaptive modulation
    (Institute of Electrical and Electronics Engineers Inc., 2016) Hamamreh, Jehad M.; Yusuf, Marwan; Baykaş, Tuncer; Arslan, Hüseyin
    In this work, Automatic-Repeat-Request (ARQ) and Maximal Ratio Combination (MRC), have been jointly exploited to enhance the confidentiality of wireless services requested by a legitimate user (Bob) against an eavesdropper (Eve). The obtained security performance is analyzed using Packet Error Rate (PER), where the exact PER gap between Bob and Eve is determined. PER is proposed as a new practical security metric in cross layers (Physical/MAC) security design since it reflects the influence of upper layers mechanisms, and it can be linked with Quality of Service (QoS) requirements for various digital services such as voice and video. Exact PER formulas for both Eve and Bob in i.i.d Rayleigh fading channel are derived. The simulation and theoretical results show that the employment of ARQ mechanism and MRC on a signal level basis before demodulation can significantly enhance data security for certain services at specific SNRs. However, to increase and ensure the security of a specific service at any SNR, adaptive modulation is proposed to be used along with the aforementioned scheme. Analytical and simulation studies demonstrate orders of magnitude difference in PER performance between eavesdroppers and intended receivers.
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    Enhancing physical-layer security in wireless communications using signal space diversity
    (Institute of Electrical and Electronics Engineers Inc., 2016) Yusuf, Marwan; Arslan, Hüseyin
    In this paper, we enhance the security of OFDM systems in frequency selective fading channels using signal space diversity. In rich multipath environments, spatially separated channels are independent to each other. Hence, by adapting the interleaving pattern to the channel of the legitimate user, more diversity gain is provided to the legitimate user compared to an eavesdropper. This ensures secrecy in a time division duplex system, where the eavesdropper has no information regarding the channel of the legitimate user. The scheme can also be used in the conventional frequency division duplex system, which is more challenging in terms of security aspects because of the channel state information leakage. We verify the gain of our scheme by showing the improvement in the bit error rate performance.
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    On signal space diversity: An adaptive interleaver for enhancing physical layer security in frequency selective fading channels
    (Elsevier Science Bv, 2017) Yusuf, Marwan; Arslan, Hüseyin
    Signal space diversity is a powerful technique that increases reliability of detection over fading channels. In this paper, we explore the ability of this technique to provide secure communication. We enhance the security of OFDM systems in frequency selective fading channels by providing more diversity gain to the legitimate user compared to an eavesdropper. This is done by adapting the interleaving pattern to the channel of the legitimate user in rich multipath environments, where spatially separated channels are typically independent to each other. This ensures secrecy in a time division duplex system, where the eavesdropper has no information regarding the channel of the legitimate user. The scheme can also be used in the conventional frequency division duplex system, which is more challenging in terms of security aspects because of the channel state information leakage. A theoretical analysis is presented on the bit-error probability in Rayleigh fading environment. The numerical results support the conclusion that adapting the interleaving pattern to the CSI of the legitimate user provides a gain in the bit-error rate performance over the eavesdropper.
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    Physical layer security schemes for wireless communication systems
    (İstanbul Medipol Üniversitesi Fen Bilimleri Enstitüsü, 2016) Yusuf, Marwan; Arslan, Hüseyin
    Security in wireless communications has always been a major concern due to the broadcast nature of the radio waves. Apart from the conventional cryptologic methods that are performed in the upper layers, physical-layer security is emerging as a promising paradigm that aims to take advantage of the random propagation characteristics of wireless channels. For the rich multipath environment, we propose a technique that exploits the inter-carrier interference, caused by a carrier frequency offset in OFDM systems, to degrade the performance of eavesdroppers. The proposed technique is based on introducing a controlled interference to pre-compensate the effect of the carrier offset only for the legitimate user in time division duplex systems. Frequency division duplex is a more challenging scenario in terms of security aspects due to the channel state information (CSI) leakage problem. We propose another technique that uses the conventional scheme of performing CSI feedback. We enhance the security of OFDM systems in frequency selective fading channels by using signal space diversity (SSD). By adapting the interleaving pattern used in SSD to the channel response of the legitimate user, more diversity gain is provided to the legitimate user compared to an eavesdropper. The smart adaptation of the interleaving pattern reduces both: the computational complexity and the diversity gain delivered to an eavesdropper compared to the conventional SSD system. For open environment, where scatterers are limited or line-of-sight dominates the communication, we introduce a complementary scheme that uses a multiple antenna technique called directional modulation in a coordinated multi-point system to provide location-specific secure transmission to legitimate users. We characterize the performance achievable using a newly defined metric called clear region. Finally we investigate the effect of the number of antennas and modulation order on the performance.
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    Secure spatial multiple access using directional modulation
    (IEEE-Institute of Electrical and Electronics Engineers Inc, 2018) Hafez, Mohammed; Yusuf, Marwan; Khattab, Tamer; Elfouly, Tarek; Arslan, Hüseyin
    In this paper, we introduce a secure multiple access scheme, which exploits the multipath structure of the channel to create a multi-user interference environment. The generated interference enables legitimate users to share time and frequency resources over spatially secure communication links. Utilizing directional modulation, we ensure secrecy for legitimate users against eavesdropping while preserving mutual confidentiality between the legitimate users themselves. Moreover, we introduce a complementary scheme for covering the non-selective channel case. The scheme uses directional modulation in coordinated multi-point transmission to provide location-specific secure communication to legitimate users. We characterize the achievable performance using a newly defined metric called vulnerable region. We provide analysis for the achievable secrecy rate, secrecy outage probability, and channel correlation effect on the secrecy performance for the proposed scheme. Furthermore, the effect of the channel spatial diversity, channel estimation error, and the number of legitimate users on the secrecy performance is studied.