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

28

Articles

11

Citation Count

148

Supervised Theses

4 Scholarly Output Search Results

Now showing 1 - 10 of 26

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
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.
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
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.
Minimum Length Scheduling for Discrete-Rate Full-Duplex Wireless Powered Communication Networks
(IEEE-Inst Electrical Electronics Engineers Inc, 2022) Şadi, Yalçın; 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.
Throughput Maximization in Discrete Rate Based Full Duplex Wireless Powered Communication Networks
(John Wıley & Sons Ltd, 2020) Iqbal, Muhammad Shahid; Şadi, Yalçın; 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.
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.
Minimum Length Scheduling for Multi-Cell Full Duplex Wireless Powered Communication Networks
(Mdpi, 2021) Iqbal, Muhammad Shahid; Şadi, Yalçın; Sadi, Yalcin; Coleri, Sinem
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.
Minimum Length Scheduling for Discrete Rate Based Full Duplex Wireless Powered Communication Networks
(Springer, 2019) Iqbal, Muhammad Shahid; Şadi, Yalçın; Şadı, Yalçın; Ergen, Sinem Coleri
In this study, we consider a wireless powered communication network where multiple users with radio frequency energy harvesting capabilities communicate to a hybrid energy and information access point in full duplex mode. We characterize an optimization framework for minimum length scheduling to determine the optimal rate adaptation and transmission scheduling subject to energy causality and traffic demand constraints of the users considering discrete-rate transmission model. 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, based on an analysis on the characteristics of the optimal solution, we derive optimality conditions for rate adaptation and scheduling using which we propose a fast polynomial-time complexity heuristic algorithm. We illustrate through numerical analysis that the proposed algorithm performs very close to optimal for various network scenarios.
Minimum Length Scheduling for Full Duplex Time-Critical Wireless Powered Communication Networks
(IEEE, 2020) Şadi, Yalçın; 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.
Energy Efficient Robust Scheduling of Periodic Sensor Packets for Discrete Rate Based Wireless Networked Control Systems
(Elsevier, 2020) Farayev, Bakhtiyar; Şadi, Yalçın; Uçar, Seyhan; Şadi, Yalçın; Coleri, Sinem
Wireless networked control systems (WNCSs) require the design of a robust scheduling algorithm that meets the stringent timing and reliability requirements of control systems, despite the limited battery resources of sensor nodes and adverse properties of wireless communication for delay and packet errors. In this article, we propose a robust delay and energy constrained scheduling algorithm based on the exploitation of the mostly pre-known periodic data generation nature of sensor nodes in control systems. We first formulate the joint optimization of scheduling, power control and rate adaptation for discrete rate transmission model, in which only a finite set of transmission rates are supported, as a Mixed-Integer Non-linear Programming problem and prove its NP-hardness. Next, we propose an optimal polynomial-time power control and rate adaptation algorithm for minimizing the transmission time of a node subset. We then design a novel polynomial-time heuristic scheduling algorithm based on first determining the concurrently transmitting node subsets and then distributing them uniformly over time by a modified Karmarkar-Karp algorithm. We demonstrate the superior performance of the proposed scheduling algorithm in terms of robustness, delay and runtime on the Low-Rate Wireless Personal Area Network (LR-WPAN) simulation platform, which we developed in network simulator-3 (ns3).
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
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.