Erdal Panayırcı

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Panayırcı, Erdal

Name Variants

P., Erdal
Panayirci,E.
Panayirci,Erdal
Erdal Panayırcı
Panayirci E.
Panayırcı,E.
Panayirci, Erdal
P.,Erdal
Erdal, Panayirci
Panayırcı E.
Panayırcı, Erdal
Panayırcı, Erdal
Panayırcı, Erdal

Job Title

Prof. Dr.

Email Address

eepanay@khas.edu.tr

ORCID ID

0000-0001-7328-6626

Scopus Author ID

7005179513

Full item page

Scholarly Output

169

Articles

62

Citation Count

298

Supervised Theses

9 Scholarly Output Search Results

Now showing 1 - 10 of 165

Optimal Rate and Power Allocation Algorithm in Tdd-Ofdm Based Two-Tier Femtocell Networks
(Kadir Has Üniversitesi, 2014) Altabaa, Mhd Tahssin; Panayırcı, Erdal; Panayırcı, Erdal
People nowadays are witnessing the acceleration of development of electronics. The new technologies of electronic devices has made mobile phones smarter and more technologically advanced, where they support software platforms and applications that increased the demands on high data rates and gives the users the ability to play online games, video chat, upload-download data, and watch videos on social networks and other video-streaming websites. According to statistics of researches and telecommunication companies, the average usage area of a mobile data transfer users are generated from indoor places e.g. houses. Mobile operators seeks out for providing high data rates to increase their capacity to suit the demands of indoor users for those who experience weak signal power; However, the current studies suggests a distance decreasing between the Mobile Station (MS) and Base Station (BS) for a lower distance of wireless communication. Femtocell technology, also called Home Base Station (HBS), provides a high data transfer rates and better coverage area for limited number of indoor users, where the conventional base station used by the telecommunication company that has a wide coverage correspondingly named Macro Base Station (MBS). In home base station technology, the femtocell users uses the same spectrum for uplink and downlink frequencies that the other mobile stations are using for communication with the MBS. However, for such a communication system, it brings out a new area for research regarding interference management. In this thesis, an adaptive power control algorithm based on the network's present parameters with two constraints performed at the femtocell users' uplink channels for interference mitigation in a Time Division Duplex-Orthogonal Frequency Division Multiplexing (TDD-OFDM) wireless communication fashion. The constraints aims to ensure the quality of service of communication of MBS's user and to preserve the data rate of femtocell users from collapsing. The first constraint is regarding the mitigation of the interference coming from the femtocell user to the macro base station; this constraint depends on the availability of the time slot that both femtocell and macrocell users are sharing subject to a certain frequency. The second constraint is regarding the limitation of the femtocell user's transmitting power based on the maximization of the weighted rate sum of the femtocell users subject to the power summation of each femtocell user on each subchannel. Accordingly, we study the scenarios that considers both the cross-tier and co-tier interferences to mimic the realistic femtocell environment.
Physical Layer Security for Multi-User Mimo Visible Light Communication Systems With Generalized Space Shift Keying
(Institute of Electrical and Electronics Engineers Inc., 2021) Su, Nugman; Panayırcı, Erdal; Panayırcı, Erdal; Koca, Mutlu; Yeşilkaya, Anıl; Poor, Harold Vincent; Haas, Harald
We consider the physical layer security (PLS) of multi-user (MU) multiple-input-multiple-output visible light communication (VLC) systems with an eavesdropper (Eve) and propose a novel spatial constellation design technique based on generalized space shift keying (MU-GSSK-SCD). The received signals of the legitimate users are optimized jointly, such that their bit error ratios (BERs) are minimized and Eve's BER is significantly degraded. The emission power of randomly selected light-emitting diodes is adjusted, by exploiting users' channel state information at the transmitter. Our strategy ensures that legitimate users receive confidential messages fully in an undistorted fashion, while any meaningful leakage to Eve is strongly prohibited, without any artificial noise addition. Every user can decode only its information, hence inter-user security is also guaranteed. The PLS improvements are presented in terms of both BERs and achievable secrecy rates in practical VLC scenarios. For various user configurations, it is shown that MU-GSSK-SCD increases the BER at Eve to the 0.5 level, while providing minimized BERs to the legitimate users. The achievable secrecy rate region is derived for MU-GSSK-SCD and it is shown that full secrecy can be achieved at 0 dB signal-to-noise ratio (SNR) level with a user separation as small as 90 cm.
Sparse Channel Estimation and Equalization for Ofdm-Based Underwater Cooperative Systemsw With Amplify-And Relaying
(IEEE-INST Electrical Electronics Engineers Inc, 2016) Panayırcı, Erdal; Şenol, Habib; Şenol, Habib; Panayırcı, Erdal; Uysal, Murat; Poor, H. Vincent
This paper is concerned with a challenging problem of channel estimation and equalization for amplify-and-forward cooperative relay based orthogonal frequency division multi-plexing (OFDM) systems in sparse underwater acoustic (UWA) channels. The sparseness of the channel impulse response and prior information for the non-Gaussian channel gains modeled by an exact continuous Gaussian mixture (CGM) are exploited to improve the performance of the channel estimation algorithm. The resulting novel algorithm initially estimates the overall sparse complex-valued channel taps from the source to the destination as well as their locations using the matching pursuit (MP) approach. The effective time-domain non-Gaussian noise is approximated well as a Gaussian noise in the frequency-domain where the estimation takes place. An efficient and low complexity algorithm is developed based on a combination of the MP and the maximum a posteriori probability (MAP) based space-alternating generalized expectation-maximization technique to improve the estimates of the channel taps and their locations in an iterative manner. Computer simulations show that the UWA channel is estimated very effectively and the proposed algorithm exhibits excellent symbol error rate and channel estimation performance.
Pilot-Aided Bayesian Mmse Channel Estimation for Ofdm Systems: Algorithm and Performance Analysis
(2004) Şenol, Habib; Şenol, Habib; Cirpan, Hakan Ali; Panayırcı, Erdal; Panayırcı, Erdal
This paper proposes a computationally efficient pilot-aided minimum mean square error (MMSE) channel estimation algorithm for OFDM systems. The proposed approach employs a convenient representation of the discrete multipath fading channel based on the Karhunen-Loeve (KL) orthogonal expansion and estimates uncorrelated series expansion coefficients. Moreover optimal rank reduction is achieved in the proposed approach by exploiting the optimal truncation property of the KL expansion resulting in a smaller computational load on the estimation algorithm. The performance of the proposed approach is studied through analytical and experimental results. We first consider the stochastic Cramer-Rao bound and derive the closed-form expression for the random KL coefficients. We then exploit the performance of the MMSE channel estimator based on the evaluation of minimum Bayesian MSE. © 2004 IEEE.
Orthogonal Frequency Division Multiplexing With Index Modulation in the Presence of High Mobility
(2013) Basar, Ertugrul; Panayırcı, Erdal; Aygölü, Ümit; Panayırcı, 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. © 2013 IEEE.
Energy-Efficient Design for Ris-Aided Cell-Free Ultra Dense Hetnets
(Institute of Electrical and Electronics Engineers Inc., 2023) Li,B.; Panayırcı, Erdal; Hu,Y.; Dong,Z.; Panayirci,E.; Jiang,H.; Wu,Q.
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. © 2023 IEEE.
Performance of Mimo Enhanced Unipolar Ofdm With Realistic Indoor Visible Light Channel Models
(Institute of Electrical and Electronics Engineers Inc., 2016) Yeşilkaya, Anıl; Panayırcı, Erdal; Miramirkhani, Farshad; Basar, Ertugrul; Panayırcı, Erdal; Uysal, Murat
Visible light communication (VLC) involves the dual use of illumination infrastructure for high speed wireless access. Designing such optical based communication systems realistic indoor optical channel modeling becomes an important issue to be handled. In this paper first we obtain new realistic indoor VL channel characterizations and models in a multiple-input multiple-output (MIMO) transmission scenario using non-sequential ray tracing approach for the channel impulse responses (CIRs). Practical issues such as number of light emitting diode (LED) chips per luminary spacing between LED chips objects inside the room and cabling topology are also investigated. On the other hand since indoor optical channels exhibit frequency selectivity multi-carrier communication systems particularly orthogonal frequency division multiplexing (OFDM) is used to handle the resulting inter-symbol interference in VLC systems. Hence we propose a new MIMO-OFDM based VLC system called MIMO enhanced unipolar OFDM (MIMO-eU-OFDM) by combining MIMO transmission techniques with the recently proposed eU-OFDM scheme. The bit error rate (BER) performance of the proposed system is investigated in the presence of the 2×2 and 4×4 realistic MIMO VLC channels and its BER performance is compared with the reference optical MIMO-OFDM systems. © 2016 IEEE.
Partial Power and Rate Adaptation for Mqam/Ofdm Systems Under Cfo
(IEEE, 2014) Dong, Zhicheng; Panayırcı, Erdal; Fan, Pingzhi; Panayırcı, Erdal; Lei, Xianfu
In this paper a new partial power and rate adaptation scheme for orthogonal frequency division multiplexing (OFDM) systems is proposed in the presence of carrier frequency offset (CFO). The conventional adaptive scheme is shown to be a special case of the partially adaptive scheme technique which enables the resulting non-convex optimization problem solved in a feasible way. It leads to a solution for optimal power adaptation that maximizes the spectral efficiency of an OFDM system using M-ary quadrature amplitude modulation (MQAM) under average power and instantaneous BER constraints. Closed-form expressions for the average spectral efficiency (ASE) of adaptive OFDM systems are derived. The theoretical results and computer simulations show that the range of the partial adaptation becomes narrow and the performance of constant power and continuous rate is very close to that of the partially adaptive power and continuous rate for higher CFO or high signal noise ratio (SNR) values.
Analysis of Visible Light Communation Sytems and Adaptive Equalization Effects
(Kadir Has Üniversitesi, 2015) Mamus, Atilla; Panayırcı, Erdal; Panayırcı, Erdal
Communication by means of visible light is a newly developing technology that has been brought up as an alternative to the current electromagnetic based communication systems. The recently conducted studies led to the use of LED Technology for illumination purposes and for this technology to have an edge over devices that consume excessive energy as presently being used by us. LED technology is predicted to become an important part of illumination systems especially in consideration of the low energy consumption low voltage use product longevity and small size the technology can provide. Furthermore the use of semi-conductor materials in the LED technology lends this illumination tool the capability to be turned on and off very fast in comparison to the other similar purpose devices. This capability makes it possible for LED technology to be used as a means of data transmission in addition to being a means of illumination. Studies are being conducted to use LEDs effectively as an optic transmission transmitter antenna and application of modulation techniques used in electromagnetic systems to VLC technology for purposes of achieving resistance against white noise reflections refractions and echoes. in literature the model of receiving data by means of adaptive filters and its processing has been used in very limited number of studies and in these studies generally LMS algorithms were used. in this dissertation an empty room in rectangular prism shape in pre-determined dimensions was used with LED panels in numbers and positions previously determined which sent data whereby the impulse response displayed by the channel until the data sent that reached the photo detector was analyzed according to different FOV angles in computer environment and later on the data was sent to the receiver through these channels that have differing impulse response based on specific FOV degrees. The data that is processed at the receiver was passed through adaptive filters to evaluate byte error rate performances in the computer environment. LMS and RLS algorithms were used in the adaptive filter. The simulation results have been displayed in graphics of bit error rate change based on SNR and it has been observed that the adaptive filter on which RLS algorithm is used provided better results than the adaptive filter on which LMS algorithm was used. bstract.
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; Panayırcı, 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.