Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Conference Object Carrier Frequency Offset Based Shared Randomness for Secure Transmission in M-Psk Noma(IEEE, 2023) Göztepe, Caner; Karabulut Kurt, Güneş; Özbek, BernaPower domain non-orthogonal multiple access (NOMA) enhances spectral efficiency by superposing multiple users in the same time-frequency resource block at the expense of exposing the users' data. However, current approaches to improve the secrecy levels of users are limited to rate reduction. This paper proposes a secure NOMA system based on the shared randomness extracted from the reciprocal carrier frequency offsets (CFOs) between the transmitter-receiver pairs for M-ary phase-shift keying. As multiple users will have physically separated oscillators, it will result in independent CFOs among users. This randomness is used to introduce a constellation rotation in the transmitted symbols. We show that under ideal CFO estimates, the proposed approach achieves perfect secrecy among all NOMA users without introducing any rate reduction. We also demonstrate the practical applicability of the proposed approach by using a software-defined radio-based test bed. © 2023 IEEE.Conference Object Citation - WoS: 3Citation - Scopus: 3Space-Frequency Grouping Based Key Extraction for Mimo-Ofdm Systems(IEEE, 2017) Topal, Ozan Alp; Karabulut Kurt, Güneş; Özbek, BernaLatest developments in wireless communication networks push the limits of conventional security methods. Security can be improved with a secret key that is dynamically generated based on the surrounding physical environment. With this objective, physical layer security approaches can be implemented by means of simple signal processing methods. In this paper, we propose novel key extraction approaches based on spatial and frequency characteristics of the wireless environment. In a 2x2 MIMO-OFDM system, low key disagreement rates and key error rates are observed, proving the potential of physical layer key extraction techniques.Article Citation - WoS: 1Citation - Scopus: 2Secure Multiuser Miso Communication Systems With Limited Feedback Link(Springer Verlag, 2018) Özbek, Berna; Özdoğan Şenol, Özgecan; Karabulut Kurt, GüneşPhysical layer security is one of the promising techniques for the security of next-generation wireless systems. In this paper, we analyze the impact of the limited feedback link on the secrecy capacity for a system which includes a base station with multiple antennas, a single legitimate user selected from multiple active ones and multiple eavesdroppers. We propose to design a limited feedback link by reducing the feedback load and quantizing the channel state information (CSI) of legitimate users to establish a secure communication system. The feedback load is decreased with a self discrimination criterion at the legitimate users’ side while keeping the secrecy capacity constant. The best legitimate user is selected based on the quantized CSI through a limited feedback link. We also analyze the impact of CSI of eavesdroppers, which information may or may not be available at transmitter. In practical cases where eavesdroppers are passive and their location is not known by the transmitter, an artificial noise is used to disrupt their reception. When the CSI of eavesdroppers is known, the generalized singular value decomposition is applied. We illustrate the performance results of the proposed limited feedback link through the availability of CSI of eavesdroppers at the transmitter.Article Citation - WoS: 20Citation - Scopus: 22Key Error Rates in Physical Layer Key Generation: Theoretical Analysis and Measurement-Based Verification(Institute of Electrical and Electronics Engineers Inc., 2017) Topal, Ozan Alp; Karabulut Kurt, Güneş; Özbek, BernaChannel gains are frequently used to obtain a secret key that can be used for encryption in physical layer security systems. However, the channel gains captured by the nodes may not always be the same due to channel estimation errors. This would result in a non-zero key error rate (KER). In this letter, we obtain theoretical expressions for KER in orthogonal frequency division multiplexing systems. Tight KER approximations are provided based on Gauss-Laguerre quadrature. A measurementbased study is conducted by using software defined radio nodes to demonstrate the validity and the practicality of the provided results.