Browsing by Author "Panayirci, Erdal"

Now showing 1 - 16 of 16

Citation - WoS: 1
Breaking the Performance Gap of Fully and Semisupervised Learning in Electromagnetic Signature Recognition
(Ieee-inst Electrical Electronics Engineers inc, 2024) Wang, Haozhi; Wang, Qing; Chen, Luyong; Fu, Guanyang; Liu, Xiaofeng; Dong, Zhicheng; Panayirci, Erdal
Intelligent electromagnetic signature recognition is one of the key technologies in Internet of Things (IoT) device connection, which can improve system security and speed up the authentication process. In practical scenarios, as the number of IoT devices increases, electromagnetic features, such as fingerprint and modulation signals also increase substantially. However, since intelligent recognition technology, such as automatic modulation classification (AMC), requires a large amount of labeled data to train the neural network classifier, it is challenging to collect so much labeled data. To address the performance degradation challenges with small training data, we propose an efficient semisupervised electromagnetic recognition framework to break the performance gap with the fully supervised learning scheme. This framework can fully use the unlabeled electromagnetic data collected during the authentication process for self-training to improve the classifier's performance. According to the idea of consistency regularization, we design a signal augmentation method and propose an ensemble pseudolabel design algorithm to improve confidence. Moreover, we perform a convex combination of electromagnetic features to smooth the model decision boundary while generalizing to unknown data distribution regions. Experimental results on the modulated data demonstrate the performance superiority of the proposed algorithm, i.e., use less than 5% of data with no more than 10% performance drop.
Citation - Scopus: 1
Design of Secure Multi-User Coded-SSK With Index Selecting Capability
(IEEE-Inst Electrical Electronics Engineers Inc, 2025) Hassan, Sumeyra; Panayirci, Erdal; Helleseth, Tor; Poor, H. Vincent
We propose a new coded space shift keying (CSSK) signaling technique for multi-user (MU), multiple-input multiple-output (MIMO) communication systems incorporating physical layer security (PLS). Besides its error correction ability, the designed linear code is capable of choosing transmit antenna indices automatically and selecting the best set of antenna combinations that minimizes the bit error rate (BER). Results obtained for the single-user (SU) schemes are then extended to a general single-cell downlink MU CSSK setting. A precoder design is proposed with a maximum ratio combining (MRC) technique to eliminate the multi-user interference (MUI) entirely by taking advantage of channel state information (CSI) at the transmitter. It is shown that the same precoding provides a very effective jamming signal for the PLS against passive eavesdroppers, degrading their signal-to-interference-plus-noise ratio (SINR) severely. A closed-form expression for the achievable secrecy rates is derived and it is maximized by the proposed power allocation algorithm. Finally, it is shown analytically and by computer simulations that substantially better BER performance is achieved by each user over interference-free transmission compared to an SU transmission with a maximum likelihood (ML) detector.
Citation - WoS: 1
Energy-Efficient Design for Ris-Aided Cell-Free Ultra Dense Hetnets
(Ieee, 2023) Li, Bin; Hu, Yulin; Dong, Zhicheng; Panayirci, Erdal; Jiang, Huilin; Wu, Qiang
In this article, we investigate the energy efficiency of reconfigurable intelligent surfaces (RISs) aided full-duplex cellfree ultra dense hetNets (CFUDN), which has the advantages of both cell-free massive MIMO (CF-MMIMO) and ultra-dense hetNets (UDN). To maximize the EE of full-duplex CFUDN, users association and clustering, RISs subsurface associations are carefully designed. Then, the phase shift matrix of RISs and transmission power of base stations are jointly optimized. Due to the non-convexity and high complexity of formulated problem, it is extremely difficult to solve this problem. At present, the block coordinate descent (BCD) algorithm is the most commonly used method for joint optimization problems. However, as we all know, the BCD algorithm has some degree of performance loss due to alternate optimization. To overcome this challenging issue, a novel joint optimization framework based on Riemannian product manifolds (RPM) is proposed.
Citation - Scopus: 2
Energy-Efficient Secure Communication for Ios Aided Cfmmimo Network
(Ieee, 2024) Li, Bin; Hu, Yulin; Dong, Zhicheng; Panayirci, Erdal; Jiang, Huilin; Wu, Qiang
In this article, we investigate the security energy efficiency (SEE) of intelligent omni-surface (IOS) aided cell-free massive MIMO (CFMMIMO) networks. Firstly, we provide a SEE maximization design for the IOS-assisted CFMMIMO network. To address the formulated non-convex, multivariate problem, in particular, we first decouple the problem into two sub-problems, and design corresponding low-complexity algorithms for each sub-problem, including the joint optimization algorithm of the access point (AP) transmission beamforming and artificial noise covariance matrix based on semi-smooth Newton method (SSNM) as well as the joint optimization algorithm of IOS reflection-transmission phase shift matrix based on Riemannian product manifolds-conjugate gradient method (RPM-CG). The two subproblems are then iterated iteratively using the Block Coordinate Descent (BCD) algorithm to obtain the maximum SEE of the IOS-assisted CFMMIMO network. Simulation results show that the proposed algorithm outperforms the five baseline schemes in terms of SEE.
Citation - Scopus: 1
Energy-Efficient Secure Design for iOS and an Aided CF-MIMO Network
(IEEE-Inst Electrical Electronics Engineers Inc, 2025) Li, Bin; Hu, Yulin; Dong, Zhicheng; Panayirci, Erdal; Jiang, Huilin; Wu, Qiang
Intelligent Omni-Surface (IOS) has attracted considerable attention for its advantages of high energy efficiency, which are similar to those of Reconfigurable Intelligent Surface (RIS), while also being able to overcome the limited scope of RIS services. In this paper, we provide a security energy efficiency (SEE) maximization design for IOS and artificial noise (AN) assisted cell-free massive MIMO (CF-mMIMO) networks, via jointly optimizing the transmission beamforming and AN covariance matrix of the AP, the reflection and transmission phase-shift matrices of the IOS, and the reflection-transmission power ratio of the IOS. To handle the formulated problem with non-convexity and high complexity, we first decouple it into two sub-problems. Then, we design low-complexity algorithms for each sub-problem i.e., an AP transmission beamforming and AN noise covariance matrix joint optimization algorithm based on the SSNCG-ALM, and an IOS reflection and transmission phase-shift matrix joint optimization algorithm based on the RPM-TR. Finally, a SEE maximization iterative algorithm based on block coordinate descent and successive convex approximation is established. The simulation results demonstrate that the proposed design significantly enhances the SEE of CF-mMIMO networks.
Citation - WoS: 4
Citation - Scopus: 5
Joint Resource Allocation in Multi-Ris and Massive Mimo-Aided Cell-Free Iot Networks
(Ieee-inst Electrical Electronics Engineers inc, 2024) Li, Bin; Hu, Yulin; Dong, Zhicheng; Panayirci, Erdal; Jiang, Huilin; Wu, Qiang
To meet the needs of high energy efficiency (EE) and various heterogeneous services for 6G, in this article, we probe into the EE of reconfigurable intelligent surfaces (RISs) subsurface (SSF) architecture-aided cell-free Internet of Things (CF-IoT) networks. Specifically, we jointly optimize the base station (BS)-RIS-IoT device (ID) joint associations, the RIS's phase shift matrix (PSM), and the BS's transmit power to enhance CF-IoT's EE. The elevated complexity (NP-hard) and nonconvexity of the formulated problem pose significant challenges, making the solution highly difficult and intricate. To handle this challenging problem, we first develop an alternating optimization framework based on block coordinate descent, which can decouple the original problem into several subproblems. We then carefully design the corresponding low-complexity algorithm for each subproblem to solve it. Moreover, the proposed joint optimization framework serves as a versatile solution applicable to a wide range of scenarios aiming to maximize EE with the assistance of RISs. Simulations confirm that deploying RISs in CF-IoT scenarios is beneficial for improving the EE of the system, and the SSF architecture can further enhance the EE of the system.
Citation - WoS: 49
Optical OFDM with Index Modulation for Visible Light Communications
(Ieee, 2015) Basar, Ertugrul; Panayirci, Erdal
In this paper, we propose optical orthogonal frequency division multiplexing with index modulation (O-OFDM-IM) for visible light communications (VLC) systems employing light emitting diodes (LEDs) and photodetectors (PDs). The proposed scheme uses the indices of the active subcarriers of an optical OFDM system to transmit additional information bits. In the proposed scheme, the bipolar signals are asymmetrically clipped or DC biased and a log-likelihood ratio (LLR) calculation based detector is used to determine the indices of the active subcarriers. Our computer simulations show that the O-OFDM-IM achieves better error peformance compared to classical optical OFDM schemes.
Citation - WoS: 30
Orthogonal Frequency Division Multiplexing With Index Modulation in the Presence of High Mobility
(Ieee, 2013) Basar, Ertugrul; Aygolu, Umit; Panayirci, Erdal
In this paper, a novel orthogonal frequency division multiplexing (OFDM) scheme, which is called OFDM with index modulation (OFDM-IM), is proposed for frequency-selective fading channels in the presence of high mobility. In this scheme, inspiring from the recently introduced spatial modulation concept for multiple-input multiple-output (MIMO) channels, the information is conveyed not only by M-ary signal constellations as in classical OFDM, but also by the indices of the subcarriers, which are activated according to the incoming bit stream. Different low complexity transceiver structures based on maximum likelihood (ML) detection or log-likelihood ratio (LLR) calculation are proposed. It is shown via computer simulations that the proposed scheme achieves significantly better error performance than classical OFDM.
Citation - WoS: 4
Citation - Scopus: 6
Physical Layer Security With Dco-Ofdm Vlc Under the Effects of Clipping Noise and Imperfect Csi
(Ieee-inst Electrical Electronics Engineers inc, 2024) Panayirci, Erdal; Bektas, Ekin B.; Poor, H. Vincent
Visible light communications (VLC) and physical-layer security (PLS) are key candidate technologies for 6G wireless communication. This paper combines these two technologies by considering an orthogonal frequency division multiplexing (OFDM) technique called DC-biased optical OFDM (DCO-OFDM) equipped with PLS as applied to indoor VLC systems. First, a novel PLS algorithm is designed to protect the DCO-OFDM transmission of the legitimate user from an eavesdropper. A closed-form expression for the achievable secrecy rate is derived and compared with the conventional DCO-OFDM without security. To analyze the security performance of the PLS algorithm under the effects of the residual clipping noise and the channel estimation errors, a closed-form expression is derived for a Bayesian estimator of the clipping noise induced naturally at the DCO-OFDM systems after estimating the optical channel impulse response (CIR), by a pilot-aided sparse channel estimation algorithm with the compressed sensing approach, in the form of the orthogonal matching pursuit (OMP), and the least-squares (LS). Finally, from the numerical and the computer simulations, it is shown that the proposed PLS algorithm with secret key exchange guarantees the eavesdropper's BER to stay close to 0.5 and that the proposed encryption-based PLS algorithm does not affect the BER performance of the legitimate user in the system.
Citation - WoS: 1
Citation - Scopus: 1
Physical Layer Security With Mimo-Generalized Space Shift Keying Modulation Technique in Li-Fi Systems
(Ieee, 2024) Hassan, Sumeyra; Panayirci, Erdal
In this study, a physical layer security algorithm based on generalized space shift keying modulation for visible light communication systems has been developed. Initially, the algorithm selects the most suitable index combinations for ideally activating the photodiodes in the receiver through a designed linear encoder, thereby enhancing error correction capabilities. Subsequently, a customized precoding matrix is developed using this index information and the channel state information to provide an optimum bit error rate for the legitimate receiver, Bob. This approach also degrades the bit error performance of the illegitimate receiver, Eve, thus ensuring high-level security at the physical layer in Li-Fi systems. Experiments conducted with Monte-Carlo simulations demonstrate the effectiveness of this methodology for scenarios requiring secure communication.
Citation - Scopus: 1
Priority-Based Sensing Strategy for ISAC Systems with Primary and Secondary Targets
(IEEE-Inst Electrical Electronics Engineers Inc, 2025) Du, Linsong; Ma, Zheng; Liang, Qingpeng; Fan, Pingzhi; Panayirci, Erdal
Integrated sensing and communication (ISAC) holds significant commercial potential in future 6G. The 3GPP technical report indicates that it is crucial to prioritize the sensing services of the ISAC system to ensure the efficient execution of critical services due to resource-constrained environments. Thus, this paper investigates priority-based resource allocation in ISAC systems, where an ISAC base station (BS) simultaneously serves a communication user (CU) and detects both a primary sensing target (PST) and a secondary sensing target (SST). First, A priority criteria for this ISAC system is proposed: 1) Above all, to ensure that the Cramer-Rao bound (CRB) for PST is maintained below a threshold; 2) Following this, the CRB of the SST should be optimized, while ensuring the communication spectral efficiency is preserved. Then, based on this criterion, three cases are derived, and for each case, a distinct resource allocation problem is formulated, yielding closed-form or semi-closed-form expressions of the optimal resource allocation for each problem. Furthermore, An algorithm is also proposed to determine the occurrence of each case and provide the corresponding optimal resource allocation. In addition, system performance under each case is analyzed based on these expressions. Finally, the simulation results demonstrate the impact of the priority strategy on performance, which is consistent with the previous performance analysis.
Riemannian Manifold Approach for RIS/IOS-Assisted Wireless Networks Design
(IEEE-Inst Electrical Electronics Engineers Inc, 2025) Li, Bin; Guo, Ning; Hu, Yulin; Panayirci, Erdal; Dong, Zhicheng
Reconfigurable Intelligent Surfaces (RIS) and Intelligent Omni-Surfaces (IOS) have emerged as transformative technologies in wireless communications, offering enhanced energy and spectral efficiency. However, the inherent characteristics of RIS/IOS also bring new challenges to the resource allocation design of RIS/IOS-assisted wireless networks, such as the nonconvexity caused by the constant modulus constraint of RIS/IOS phase shift elements and the complexity of jointly designing RIS/IOS phase shifts and base station beamforming. Although existing approaches, such as the max-min algorithm and the alternating optimization algorithm, can address these challenges, they suffer from high computational complexity. This paper systematically analyzes the challenges in the design of RIS/IOS-assisted wireless networks and briefly introduces the principles of Riemannian manifold optimization. To address these complex design challenges, we introduce four pivotal manifolds: the complex circle manifold, sphere manifold, Cholesky manifold, and product manifold, each providing unique solutions for enhancing network performance. Finally, we discuss future research directions for Riemannian manifold methods in the design of RIS/IOS-assisted networks.
Secure Optical Coded GSSK System with Dimming
(IEEE, 2024) Hassan, Sumeyra; Panayirci, Erdal; Helleseth, Tor; Poor, H. Vincent
In this work, we develop an indoor visible light communications (VLC) system based on a transmitted precoded (TPC)-aided, coded generalized space shift keying (GSSK) system with physical layer security (PLS) capability in the presence of dimming. A new design of the encoder and decoder of linear codes is given to improve the error-correcting capability of the system as well as to enable random selection of the activated indices in the GSSK automatically. The PLS of the system is guaranteed by the appropriate selection of the power allocation coefficients for randomly activated photodiodes (PDs). At the receiver, the unknown channel and dimming coefficients are jointly estimated in the legitimate users with a new pilot-aided estimation technique. Then, the optimal detection of the spatial symbols is implemented using the maximum likelihood (ML) criterion in the presence of dimming. It is shown that the dimming coefficients, unknown to the eavesdropper, provide additional PLS for the legitimate user. The computer simulations show that the legitimate user achieves excellent bit error performance mainly due to the linear coding employed that serves for error correction and selection of the best GSSK constellation in the system. In contrast, the bit error performance of the potential eavesdroppers is significantly degraded.
Citation - WoS: 11
Spatial Modulation Aided Physical Layer Security for NOMA-VLC Systems
(Ieee-inst Electrical Electronics Engineers inc, 2023) Panayirci, Erdal; Koca, Mutlu; Haas, Harald; Poor, H. Vincent
We consider the physical layer security (PLS) problem in multi-user non-orthogonal multiple access (NOMA) enabled multiple-input multiple-output (MIMO) visible light communication systems intercepted by a passive eavesdropper (Eve). We propose a novel transmit precoding scheme based on receive spatial modulation (RSM) to degrade the signal-to-interference-noise ratio (SINR) of Eve by exploiting only the slow-fading characteristics of the visible light channel of the legitimate users (Bobs). The proposed PLS precoder is reinforced with secret parameter exchange with Bobs and a CSI acquisition model is proposed to reduce the PLS algorithm's computational load substantially at the transmitter. The closed-form expressions for the achievable secrecy rates and their upper and lower bounds are derived. Via Monte Carlo simulations, we confirm that Bobs can successfully decode their information in various user configurations while Eve's received SINR is significantly worsened by the jamming signal induced by the proposed precoder with secret key exchange. It is also shown that Eve's bit error rate (BER) is increased to the 0.5-level for almost any position in the considered indoor environment. Finally, we corroborate the derived secrecy expressions by computer simulations and show that the proposed scheme provides PLS for Bobs.
Citation - Scopus: 5
Transmit Precoding for Physical Layer Security of Mimo-Noma Visible Light Communications
(Ieee, 2021) Su, Nugman; Panayirci, Erdal; Koca, Mutlu; Haas, Harald
We consider the physical layer security (PLS) of non-orthogonal multiple access (NOMA) enabled multiple-input multiple-output (MIMO) visible light communication systems in the presence of a passive eavesdropper (Eve). In order to disrupt the decoding process at Eve, we propose a novel precoding scheme reinforced with random constellation coding. Multiple legitimate users (Bobs) will be served simultaneously using NOMA. For the proposed precoder design, we exploit the slow-fading characteristics of the visible light channel so that the transmitted symbols are successfully decoded at Bob, while Eve suffers from very high bit error ratios (BERs) due to precoding-induced jamming. Via computer simulations, we show that Bob can successfully decode their own information in various user configurations and receiver diversities. It is also shown that the BER at Eve's side is increased to the 0.5-level for similar and the asymmetrical positioning of Bob with respect to the transmitter, thus PLS is ensured by the proposed precoding technique.
Citation - WoS: 1
Trellis Code Design for Spatial Modulation
(Ieee, 2011) Basar, Ertugrul; Aygolu, Umit; Panayirci, Erdal
In this paper, we propose a novel multiple-input multiple-output (MIMO) transmission scheme, called trellis coded spatial modulation (TC-SM) in which a trellis (convolutional) encoder and a spatial modulation (SM) mapper are jointly designed similar to the conventional trellis coded modulation (TCM). A soft decision Viterbi decoder, which is fed with the soft information supplied by the optimal SM decoder, is used at the receiver. The pairwise error probability (PEP) upper bound is derived for the TC-SM scheme in uncorrelated quasi-static Rayleigh fading channels. From the PEP upper bound, code design criteria are given and then used to obtain new 4-, 8- and 16-state TC-SM schemes using QPSK (quadrature phase-shift keying) and 8-PSK modulations for 2 and 3 bits/s/Hz spectral efficiencies. It is shown via computer simulations that the proposed TC-SM schemes achieve significantly better error performance than their counterparts at the same spectral efficiency, yet with reduced decoding complexity.