Devam etmekte olan 114E244 numaralı TÜBİTAK-1001 projesi kapsamında şu ana kadar yapılan çalışmaların sonuçları aşağıdaki uluslararası yayınlarda sunulmuştur.

  • H. M. Furqan, J. M. Hamamreh, H. Arslan, “Secure Communication via Untrusted Switchable Decode-and-Forward Relay,” IEEE International Wireless Communications and Mobile Computing Conference (IWCMC), 1-4, June 26-30, 2017.

“In this paper, a practical power efficient technique is proposed for an untrusted decode-and-forward (DAF) based cooperative communication system to provide secure communication between the source and the destination. More specifically, a DAF relay, called switchable DAF (sDAF), is designed in such a way that it can be switched to amplify-and-forward (AAF) in certain predefined situations. The algorithm is based on destination-assisted jamming and comprised of two phases. The first phase securely shares the random manipulating sequence (RMS) through an untrusted relay, while the second phase uses this RMS for secure communication through untrusted relay. This algorithm not only provides secrecy, but also enhances the power efficiency as compared to other destination-assisted jamming techniques.”

  • J. M. Hamamreh, H. M. Furqan, H. Arslan, “Secure Pre-coding and Post-coding for OFDM Systems along with Hardware Implementation,” IEEE International Wireless Communications and Mobile Computing Conference (IWCMC), 1-6, June 26-30, 2017.

“An effective and hardware-friendly physical layer security design composed of a channel-based frequency pre- coder and a post-coder for OFDM-based systems is proposed. The design is achieved by decomposing the diagonal matrix of the channel frequency amplitude of the legitimate receiver in order to obtain two unitary orthonormal matrices. The first matrix is used as a pre-coder just before the IFFT process at the transmitter, while the second matrix is used as a post-coder just after the FFT process at the receiver. Besides security, the presented design is interestingly found out to work as a shuffler or inter-leaver, which does not only provide secrecy, but also enhances the performance against burst errors. Moreover, a new channel calibration technique is developed to overcome the effect of channel reciprocity mismatch on the proposed scheme. The provided simulations and USRP hardware testbed implementation results validate the effectiveness of the proposed design in achieving practical and reliable secrecy with minor modifications on the OFDM structure.”

  • J. M. Hamamreh, H. Arslan, “Secure Orthogonal Transform Division Multiplexing (OTDM) Waveform for 5G and Beyond,” accepted for publication in IEEE Communications Letters. (Date of Publication: 11 January 2017, http://ieeexplore.ieee.org/document/7814269)

“In this work, a secure waveform design for future 5G wireless systems is proposed. The developed waveform, referred to as secure orthogonal transform division multiplexing (OTDM) waveform, is designed to diagonalize the multi-path channel matrix of only the legitimate receiver (Bob), while degrading eavesdropper’s reception. In particular, instead of using fixed exponential basis functions, generated by IFFT and FFT as in OFDM, orthogonal transform basis functions, which are extracted from the channel, are utilized to modulate and demodulate the data symbols. The simulation results prove that the proposed design provides a significant practical security gap between Bob’s and Eve’s performance. The design is shown to be robust against channel imperfection, and it neither sacrifices communication resources nor considers any knowledge on the eavesdropper’s channel. Besides security, the scheme results in a higher SNR, leading to a 3-5 dB gain over OFDM at BER=10^-3.”

  • M. Yusuf, H. Arslan, “Enhancing Physical-Layer Security in Wireless Communications Using Signal Space Diversity,” IEEE Military Communications Conference (MILCOM), 1190-1194, Nov. 1-3, 2016. (http://ieeexplore.ieee.org/document/7795492)

“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.”

  • H. M. Furqan, J. M. Hamamreh, H. Arslan, “Secret Key Generation Using Channel Quantization with SVD for Reciprocal MIMO Channels,” IEEE International Symposium on Wireless Communication Systems (ISWCS), 597-602, Sept. 20-23, 2016. (http://ieeexplore.ieee.org/document/7600974)

“The generation of secret keys from reciprocal wireless channel by exploiting their randomness nature, is an emerging area of interest to provide secure communication. One of the main challenges in this domain is to increase the secret key length, extracted from the shared channel coefficients between two legitimate communication parties, while maintaining its randomness and uniformity. In this work, we develop a practical key generation method, based on channel quantization with singular value decomposition (CQSVD), which is capable of significantly increasing the generated secret key in MIMO systems. This is achieved through quantizing the phases and amplitudes of the estimated MIMO channel coefficient’s matrix by using an alternative form of SVD, where the key sequence is extracted from the orthogonal basis functions of the decomposed channel. In this method, it is shown that for an MxM antenna system, with M^2 independent channel fading coefficients, a secret key sequence of length 2M^3 can be generated. The extracted key sequence is transformed to a random phase sequence, which is then used to manipulate the transmitted data on a symbol level basis rather than bit level-basis, to provide more secure communication. The comparative simulation results show that the proposed CQSVD method outperforms the state of the art secret key generation methods.”

  • M. Yusuf, H. Arslan, “Controlled Inter-carrier Interference for Physical Layer Security in OFDM Systems,” IEEE Vehicular Technology Conference (VTC-Fall), 1-5, Sept. 18-21, 2016.

“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.”

  • J. M. Hamamreh, E. Guvenkaya, T. Baykas, H. Arslan, “A Practical Physical-Layer Security Method for Precoded OSTBC-Based Systems,” IEEE Wireless Communications and Networking Conference (WCNC), 1-6, Apr. 3-6, 2016. (http://ieeexplore.ieee.org/document/7564990)

“In this work, we investigate the security performance obtained by employing a practical precoded orthogonal space time block coding method (POSTBC) in MISO wireless networks. In particular, space time codewords are precoded with an optimum matrix that minimizes the error rate at only the legitimate user (Bob). The acquired results depict that there exists a security gap region in the resulting BER performance as a consequence of using POSTBC. Moreover, we enhance the performance more by developing a new hybrid and green security method called precoding along with partial pre-equalizing (PCPPE). In this method, the transmitted symbols are precoded by a new precoder composed of both the original precoder and a new designed unitary matrix that maps Bob’s channel amplitudes or phases estimated over the transmitting antennas into 2D orthonormal matrix. Additionally, three issues associated with the proposed security method have been tackled. Including: the slight increase in the transmit power, the appropriate selection process of the optimal precoding matrix, and the effect of imperfect channel estimation and reciprocity. The comparative simulation results prove that PCPPE method provides a secure link among the legitimate parties without sacrificing Bob’s reliability although an eavesdropper is assumed to be fully aware of the used method and the original selected precoding matrix indicator (PMI).”

  • J. M. Hamamreh, M. Yusuf, T. Baykas, H. Arslan, “Cross MAC/PHY Layer Security Design Using ARQ with MRC and Adaptive Modulation,” IEEE Wireless Communications and Networking Conference (WCNC), 1-7, Apr. 3-6, 2016. (http://ieeexplore.ieee.org/document/7564987)

“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.”

  • M. Yusuf, H. Arslan, “Secure Multi-User Transmission using CoMP Directional Modulation,” IEEE 82nd Vehicular Technology Conference (VTC Fall), Short Paper, 1-2, Sept. 6-9, 2015. (http://ieeexplore.ieee.org/document/7391131)

“Directional Modulation is a recently developed multi-antenna technique for secure transmission. It allows to transmit signals in desired directions while distorting the signal in the other directions. To secure the transmission in a scenario where eavesdropper is in the same direction as legitimate user, a coordinated multipoint scheme is proposed to have a location- specific secure communication that works even when a rich scattering environment is not available. Simulations are presented to verify the proposed scheme using 3 base stations.”

  • M. Soltani, T. Baykas, H. Arslan, “Achieving Secure Communication Through Pilot Manipulation,” IEEE 26th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC), 527-531, Aug. 30 – Sept. 2, 2015. (http://ieeexplore.ieee.org/document/7343356)

“Raising concerns about the security of wireless communication led researchers develop new concepts to keep information secret from eavesdroppers. Among them, physical layer security relies on the features of the wireless channels. Most of the work in physical layer security does focus on data transmission. On the other hand the focus of this work is to use manipulation of pilot tones to enhance communication security and to reduce eavesdroppers’ ability to estimate the wireless channel. Particularly, we are introducing two novel algorithms, which manipulate pilot tones according to legitimate channels’ phase and amplitude characteristics. Both algorithms decrease the channel estimation quality of the eavesdropper considerably, while the amplitude based algorithm provides high quality reception at the legitimate receiver. We provide resulting pilot error rates due to proposed algorithms. In addition, we show the effect of threshold selection to channel estimation quality both at the legitimate receiver and eavesdropper.”

Yine aynı TÜBİTAK projesinden sağlanacak destek ile 1 Ağustos 2017 tarihinde “Haberleşme Teknolojileri ve Uygulamaları Çalıştayı” düzenlenecektir. Bu çalıştayın düzenli olarak her sene yapılması planlanmaktadır. Aşağıdaki linkten çalıştay afişine ve çalıştay ile ilgili diğer bilgilere erişilebilmektedir.

http://cosinc.medipol.edu.tr/workshop/