Yalçın Şadi

Şadi, Yalçın

Name Variants

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

ORCID ID

0000-0002-8378-5688

Scopus Author ID

36844802900

Full item page

Scholarly Output Search Results

Now showing 1 - 10 of 24

Citation Count: 13
Minimum Length Scheduling for Full Duplex Time-Critical Wireless Powered Communication Networks
(IEEE, 2020) Iqbal, Muhammad Shahid; Şadi, Yalçın; Coleri, Sinem
Radio frequency (RF) energy harvesting is key in attaining perpetual lifetime for time-critical wireless powered communication networks (WPCNs) due to full control on energy transfer, far field region, small and low-cost circuitry. In this paper, we propose a novel minimum length scheduling problem to determine the optimal power control, time allocation and schedule subject to data, energy causality and maximum transmit power constraints in a full-duplex WPCN. We first formulate the problem as a mixed integer non-linear programming problem and conjecture that the problem is NP-hard. As a solution strategy, we demonstrate that the power control and time allocation, and the scheduling problems can be solved separately in the optimal solution. For the power control and time allocation problem, we derive the optimal solution by evaluating Karush-Kuhn-Tucker conditions. For the scheduling, we introduce a penalty function allowing reformulation of the problem as a sum penalty minimization problem. Upon derivation of the optimality conditions based on the characteristics of the penalty function, we propose two polynomial-time heuristic algorithms and a reduced-complexity exact algorithm employing smart pruning techniques. Via extensive simulations, we illustrate that the proposed heuristic schemes outperform the schemes for predetermined transmission order of users and achieve close-to-optimal solutions.
Citation Count: 1
The Effect of Codebook Design on the Conventional SCMA System Performance
(Institute of Electrical and Electronics Engineers Inc., 2020) Kiraci, F.; Bardakci, E.; Sadi, Y.; Erkucuk, S.
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-noiseratio (SNR) region. © 2020 IEEE.
Citation Count: 6
Minimum Length Scheduling for Discrete-Rate Full-Duplex Wireless Powered Communication Networks
(IEEE-Inst Electrical Electronics Engineers Inc, 2022) Iqbal, Muhammad Shahid; Sadi, Yalcin; Coleri, Sinem
Wireless powered communication networks (WPCNs) will act as a major enabler of massive machine type communications (MTCs), which is a major service domain for 5G and beyond systems. The MTC networks will be deployed by using low-power transceivers with finite discrete configurations. This paper considers minimum length scheduling problem for full-duplex WPCNs, where users transmit information to a hybrid access point at a rate chosen from a finite set of discrete-rate levels. The optimization problem considers energy causality, data and maximum transmit power constraints, and is proven to be NP-hard. As a solution strategy, we define the minimum length scheduling (MLS) slot, which is slot of minimum transmission completion time while starting transmission at anytime after the decision time. We solve the problem optimally for a given transmission order based on the optimality analysis of MLS slot. For the general problem, we categorize the problem based on whether the MLS slots of users overlap over time. We propose optimal algorithm for non-overlapping scenario by allocating the MLS slots, and a polynomial-time heuristic algorithm for overlapping scenario by allocating the transmission slot to the user with earliest MLS slot. Through simulations, we demonstrate significant gains of scheduling and discrete rate allocation.
Citation Count: 27
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
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.
Quality of Service Constrained Scheduling for Massive M2m Communications in Future Cellular Networks
(Kadir Has Üniversitesi, 2018) Mohemine, Muhammad Abdul; Şadi, Yalçın
Radio resource allocation for massive M2M communications is one of the key problems in next generation cellular networks. Satisfying strict and very diverse quality-of-service requirements increases the hardness of this problem. in this thesis flexible scheduling problem for massive M2M communications is solved considering the physical layer architecture of 5G cellular networks. First envisioned physical layer architectures and waveforms proposed for 5G are investigated and a physical layer architecture model that will allow flexible resource allocation is proposed. Then a flexible radio resource allocation algorithm is proposed based on this model. The performance of the algorithm is shown through extensive simulations.
Radio Access Management Using Multiple Numerologies for Massive Machine Type Communications Towards 6g
(Kadir Has Üniversitesi, 2022) ÇAĞAN, YAĞIZ CAN; Yalçın Şadi
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.
Noma-based Radio Resource Allocation For Machine Type Communications İn 5g And Beyond Cellular Networks 5g ve Ötesi Hücresel Ağlarda Makine Tipi İletişim için Noma Tabanlı Radyo Kaynak Atama
(Kadir Has Üniversitesi, 2021) Aldemir, Sümeyra; Şadi, Yalçın
The rapid increase of machine-to-machine (M2M) communications brings challenges in the design of cellular networks. The adversity of meeting the Quality-of-Service (QoS) requirements of a massive number of machine-type communications (MTC) devices with insufficient radio resources has emerged. The main goal of this thesis is to investigate the minimum bandwidth resource allocation problem for non-orthogonal multiple access (NOMA) based M2M communications in 5G and beyond cellular networks. A polynomial-time persistent resource allocation algorithm considering NOMA and the periodicity of the MTC traffic is proposed to solve the problem fast and efficiently. The proposed algorithm consists of two phases. In the first phase, M2M clusters are grouped into NOMA sub-clusters using a technique that minimizes the number of NOMA sub-clusters for a set of devices. NOMA sub-clusters are then allocated to resource blocks (RB) in the second phase, considering their 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 addressing the spectrum-scarcity issue.
Semi Persistent Radio Resource Allocation for Machine Type Communications in 5g and Beyond Cellular Networks
(Kadir Has Üniversitesi, 2018) Haj Hussıen, Zaid; Şadi, Yalçın
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. We elaborate on the expected flexible physical layer structure and study its possible effects on our algorithm. Simulations show that the proposed algorithm outperforms the previously proposed clustering-based radio resource algorithms significantly and performs very close to optimal.
Citation Count: 1
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
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.
Citation Count: 8
Throughput Maximization in Discrete Rate Based Full Duplex Wireless Powered Communication Networks
(John Wıley & Sons Ltd, 2020) Iqbal, Muhammad Shahid; Şadi, Yalçın; Coleri, Sinem
In this study, we consider a discrete rate full-duplex wireless powered communication network. We characterize a novel optimization framework for sum throughput maximization to determine the rate adaptation and transmission schedule subject to energy causality and user transmit power. We first formulate the problem as a mixed integer nonlinear programming problem, which is hard to solve for a global optimum in polynomial-time. Then, we investigate the characteristics of the solution and propose a polynomial time heuristic algorithm for rate adaptation and scheduling problem. Through numerical analysis, we illustrate that the proposed scheduling algorithm outperforms the conventional schemes such as equal time allocation half-duplex and on-off transmission schemes for different initial battery levels, hybrid access point transmit power and network densities.