Şadi, Yalçın

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ŞADI, Yalçın
Şadi,Y.
Sadi,Y.
Yalçın Şadi
ŞADI, YALÇIN
Şadi, Y.
Sadi, Y.
Y. Sadi
Yalçın ŞADI
YALÇIN ŞADI
Sadi,Yalcin
S., Yalcin
Sadi, Yalçın
Şadi, Yalçın
Yalçın Sadi
Sadi Y.
Ş., Yalçın
Y. Şadi
Şadi, YALÇIN
Sadi, Yalcin
Yalcin, Sadi
S.,Yalcin
Şadi Y.
Şadi, Yalçın
Job Title
Dr. Öğr. Üyesi
Email Address
yalcin.sadi@khas.edu.tr
Main Affiliation
Electrical-Electronics Engineering
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Website
ORCID ID
0000-0002-8378-5688
Scopus Author ID
36844802900
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Google Scholar ID
WoS Researcher ID
AAA-8692-2019

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Scholarly Output

29

Articles

12

Citation Count

148

Supervised Theses

4

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2017 - 201962020 - 202521
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Scholarly Output Search Results

Now showing 1 - 10 of 27
  • Thumbnail Image
    Article
    Citation - WoS: 14
    Citation - Scopus: 22
    Qos-Constrained Semi-Persistent Scheduling of Machine-Type Communications in Cellular Networks
    (IEEE, 2019) Karadağ, Göksu; Şadi, Yalçın; Gül, Recep; Sadi, Yalçın; Ergen, Sinem Coleri; Electrical-Electronics Engineering
    The dramatic growth of machine-to-machine (M2M) communication in cellular networks brings the challenge of satisfying the quality of service (QoS) requirements of a large number of M2M devices with limited radio resources. In this paper we propose an optimization framework for the semi-persistent scheduling of M2M transmissions based on the exploitation of their periodicity with the goal of reducing the overhead of the signaling required for connection initiation and scheduling. The goal of the optimization problem is to minimize the number of frequency bands used by the M2M devices to allow fair resource allocation of newly joining M2M and human-to-human communications. The constraints of the problem are delay and periodicity requirements of the M2M devices. We first prove that the optimization problem is NP-hard and then propose a polynomial-time heuristic algorithm employing a fixed priority assignment according to the QoS characteristics of the devices. We show that this heuristic algorithm provides an asymptotic approximation ratio of 2.33 to the optimal solution for the case where the delay tolerances of the devices are equal to their periods. Through extensive simulations we demonstrate that the proposed algorithm performs better than the existing algorithms in terms of frequency band usage and schedulability.
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    Conference Object
    Citation - WoS: 1
    Citation - Scopus: 3
    Noma-Based Radio Resource Allocation for Machine Type Communications in 5g and Beyond Cellular Networks
    (IEEE, 2021) Aldemir, Sumeyra; Şadi, Yalçın; Sadi, Yalcin; Erküçük, Serhat; Erkucuk, Serhat; Okumus, F. Batuhan; Electrical-Electronics Engineering
    In this paper, the minimum bandwidth resource allocation problem for non-orthogonal multiple access (NOMA) based machine to machine (M2M) communications in 5G and beyond cellular networks is investigated. In order to solve the problem fast and efficiently, a persistent resource allocation based polynomial-time algorithm considering NOMA and the periodicity of the machine type communication traffic is proposed. The algorithm consists of two phases. In first phase, M2M clusters are divided into NOMA sub-clusters using a technique that minimizes the number of NOMA sub-clusters for a set of devices. In second phase, NOMA sub-clusters are allocated to resource blocks (RB) considering their quality of service (QoS) requirements while achieving minimum bandwidth reservation. Through simulations, the performance of the proposed algorithm is presented in comparison to the previously proposed access grant time interval (AGTI) based radio resource allocation algorithms. It is illustrated that the proposed algorithm improves the spectrum-efficiency significantly.
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    Article
    Citation - WoS: 35
    Citation - Scopus: 38
    Joint Optimization of Wireless Network Energy Consumption and Control System Performance in Wireless Networked Control Systems
    (IEEE-INST Electrical Electronics Engineers Inc, 2017) Şadi, Yalçın; Ergen, Sinem Coleri; Electrical-Electronics Engineering
    Communication system design for wireless networked control systems requires satisfying the high reliability and strict delay constraints of control systems for guaranteed stability with the limited battery resources of sensor nodes despite the wireless networking induced non-idealities. These include non-zero packet error probability caused by the unreliability of wireless transmissions and non-zero delay resulting from packet transmission and shared wireless medium. In this paper we study the joint optimization of control and communication systems incorporating their efficient abstractions practically used in real-world scenarios. The proposed framework allows including any non-decreasing function of the power consumption of the nodes as the objective any modulation scheme and any scheduling algorithm. We first introduce an exact solution method based on the analysis of the optimality conditions and smart enumeration techniques. Then we propose two polynomial-time heuristic algorithms based on intelligent search space reduction and smart searching techniques. Extensive simulations demonstrate that the proposed algorithms perform very close to optimal and much better than previous algorithms at much smaller runtime for various scenarios.
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    Article
    Citation - WoS: 0
    Citation - Scopus: 0
    Resource Allocation for Multi-Cell Full-Duplex Wireless Powered Communication Networks
    (Springer, 2024) Şadi, Yalçın; Sadi, Yalcin; Kazmi, Syed Adil Abbas; Coleri, Sinem; Electrical-Electronics Engineering
    Wireless powered communication networks (WPCNs) are crucial in achieving perpetual lifetime for the machine-type communication (MTC) and Internet of things (IoT) in fifth-generation (5G) communication and beyond networks. Practical WPCNs cover a broad region and have a significant number of sensors, requiring multi-cell deployment. We investigate the minimum length scheduling problem for a multi-cell full-duplex WPCNs to find the optimal power and schedule by considering the simultaneous transmission, maximum transmit power and energy causality constraints for the users. The optimization problem to minimize the schedule length is combinatorial, thus, difficult to find the global optimum solution. To overcome this, we divide the problem into two subproblems, i.e., power control problem (PCP) and the scheduling problem. Then, we present the optimal polynomial time algorithm for the PCP based on the use of the bisection method and evaluation of the Perron-Frobenius criteria. Then, by using the PCP solution, we calculate the optimal transmission time for the users that are scheduled by the scheduling algorithm. For the scheduling problem, we define a penalty function that represents the gain of simultaneous transmission over the individual transmission of the users and we show that the minimization of schedule length is similar to the minimization of sum of penalties. Following the optimum analysis of the proposed penalty metric, we present a heuristic algorithm that tries to minimize the sum penalties of the simultaneously transmitting users over the schedule. Through extensive simulations, we show significant gains of scheduling for concurrent transmissions over individual transmissions.
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    Conference Object
    Citation - WoS: 2
    Citation - Scopus: 14
    Flexible Radio Resource Allocation for Machine Type Communications in 5g Cellular Networks
    (Institute of Electrical and Electronics Engineers Inc., 2018) Hussien, Zaid Haj; Şadi, Yalçın; Şadi, Yalçın; Electrical-Electronics Engineering
    The fast growth of machine-to-machine (M2M) communications in cellular networks brings the challenge of satisfying diverse Quality-of-Service (QoS) requirements of massive number of machine type communications (MTC) devices with limited radio resources. In this study we first introduce the minimum bandwidth resource allocation problem for M2M communications in 5G and beyond cellular networks. NP-hardness of the problem is proven. Then we propose a fast and efficient polynomial-time algorithm exploiting the periodicity of the MTC traffic based on persistent resource allocation. We prove a mathematical performance result for this algorithm considering a special case of the problem. Simulations show that the proposed algorithm outperforms the previously proposed clustering based radio resource algorithm significantly and performs very close to optimal. © 2018 IEEE.
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    Conference Object
    Citation - WoS: 22
    Citation - Scopus: 30
    Physical-Layer Security in Visible Light Communications
    (Institute of Electrical and Electronics Engineers Inc., 2020) Yeşilkaya, Anıl; Şadi, Yalçın; Çoğalan, Tezcan; Erküçük, Serhat; Erküçük, Serhat; Panayırcı, Erdal; Şadi, Yalçın; Panayırcı, Erdal; Haas, Harald; Poor, Harold Vincent; Electrical-Electronics Engineering
    Optical wireless communications (OWC) and its potential to solve physical layer security (PLS) issues are becoming important research areas in 6G communications systems. In this paper, an overview of PLS in visible light communications (VLC), is presented. Then, two new PLS techniques based on generalized space shift keying (GSSK) modulation with spatial constellation design (SCD) and non-orthogonal multiple access (NOMA) cooperative relaying are introduced. In the first technique, the PLS of the system is enhanced by the appropriate selection of a precoding matrix for randomly activated light emitting diodes (LEDs). With the aid of a legitimate user's (Bob's) channel state information (CSI) at the transmitter (CSIT), the bit error ratio (BER) of Bob is minimized while the BER performance of the potential eavesdroppers (Eves) is significantly degraded. In the second technique, superposition coding with uniform signaling is used at the transmitter and relays. The design of secure beamforming vectors at the relay nodes along with NOMA techniques is used to enhance PLS in a VLC system. Insights gained from the improved security levels of the proposed techniques are used to discuss how PLS can be further improved in future generation communication systems by using VLC.
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    Conference Object
    Citation - Scopus: 0
    Time of Arrival Estimation Performance of Vdes-R Mode With the Presence of Multipath Propagation
    (Institute of Electrical and Electronics Engineers Inc., 2023) Tüfekçi,T.K.; Şadi, Yalçın; Şadi,Y.; Esenyurt,H.Ş.; Electrical-Electronics Engineering
    Global Navigation Satellite System is responsible for providing vessels at sea with navigational information such as positioning; however, to lighten the burden on GNSS and create a backup system, VDES R-Mode is being investigated. Using R-Mode positioning information can be obtained using already existing VDES equipment and decrease the dependency on GNSS. Time of arrival estimation is the pillar of R-Mode, and this work investigates the performance of R-Mode with multipath propagation using a modified version of Ziv Zakai Bound. © 2023 IEEE.
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    Article
    Citation - WoS: 4
    Citation - Scopus: 4
    Minimum Length Scheduling for Multi-Cell Full Duplex Wireless Powered Communication Networks
    (Mdpi, 2021) Iqbal, Muhammad Shahid; Şadi, Yalçın; Sadi, Yalcin; Coleri, Sinem; Electrical-Electronics Engineering
    Wireless powered communication networks (WPCNs) will be a major enabler of massive machine type communications (MTCs), which is a major service domain for 5G and beyond systems. These MTC networks will be deployed by using low-power transceivers and a very limited set of transmission configurations. We investigate a novel minimum length scheduling problem for multi-cell full-duplex wireless powered communication networks to determine the optimal power control and scheduling for constant rate transmission model. The formulated optimization problem is combinatorial in nature and, thus, difficult to solve for the global optimum. As a solution strategy, first, we decompose the problem into the power control problem (PCP) and scheduling problem. For the PCP, we propose the optimal polynomial time algorithm based on the evaluation of Perron-Frobenius conditions. For the scheduling problem, we propose a heuristic algorithm that aims to maximize the number of concurrently transmitting users by maximizing the allowable interference on each user without violating the signal-to-noise-ratio (SNR) requirements. Through extensive simulations, we demonstrate a 50% reduction in the schedule length by using the proposed algorithm in comparison to unscheduled concurrent transmissions.
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    Conference Object
    Citation - WoS: 0
    The Effect of Codebook Design on the Conventional Scma System Performance
    (IEEE, 2020) Kiracı, Furkan; Şadi, Yalçın; Bardakçı, Emine; Erküçük, Serhat; Sadi, Yalçın; Erküçük, Serhat; Electrical-Electronics Engineering
    In 4G systems, Orthogonal Frequency-Division Multiple Access (OFDMA) has been used conventionally for multiple access purposes. This technique has low spectral efficiency since it allocates the resources orthogonally to each user. As an alternative to this technique, Non-orthogonal Multiple Access (NOMA) has been proposed for new generation systems as it allows different users to use the same resources and therefore, increases spectral efficiency. Sparse Code Multiple Access (SCMA) is a code-based NOMA technique and its performance depends on codebook design. In this study, a conventionally used codebook design in the literature has been considered and the system performance has been improved by increasing the distance between the signal constellation points. Considering two different design approaches, the conventional codebook has been modified and about 1dB gain has been achieved in the high signal-to-noise-ratio (SNR) region.
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    Master Thesis
    Radio Access Management Using Multiple Numerologies for Massive Machine Type Communications Towards 6g
    (Kadir Has Üniversitesi, 2022) ÇAĞAN, YAĞIZ CAN; Şadi, Yalçın; Yalçın Şadi; Electrical-Electronics Engineering
    As 5G and beyond cellular systems aim at providing primary support for machine type communications (MTC) under the domain of massive MTC (mMTC), 5G New Radio introduces many flexible physical layer features to enable massive connec tivity while satisfying diverse service and traffic requirements of MTC services. In this thesis, optimal radio resource management for periodic MTC traffic towards 6G networks is investigated considering multiple numerologies supported by New Radio. An optimization framework to minimize the total bandwidth required while meeting the periodic data generation requirements of MTC services is presented. Two alternative optimization problem formulations are provided along with a com parative computational complexity analysis. For both optimization problems, semi persistent radio resource allocation algorithms are proposed. The first phase of both algorithms provides optimal numerology selection and bandwidth partitioning for MTC services and the second phase performs periodic allocation of MTC services in each bandwidth part based on maximum utilization of each band. Simulations il lustrate that the proposed algorithms outperform single numerology-based resource allocation algorithms in terms of spectral efficiency and use multiple numerologies effectively.