Researcher:
Şadi, Yalçın

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Yalçın

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Şadi

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Şadi, Yalçın

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2010 - 201710

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Researcher Of Publications: search.filters.isAuthorOfPublication.6509aed6-9933-4fc3-99ce-3ef826bcd440

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    Optimal power control, rate adaptation, and scheduling for uwb-based intravehicular wireless sensor networks
    (Institute of Electrical and Electronics Engineers (IEEE), 2013) N/A; Department of Electrical and Electronics Engineering; Şadi, Yalçın; Ergen, Sinem Çöleri; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 7211
    The intravehicular wireless sensor network (IVWSN) is a promising new research area that can provide part cost, assembly, maintenance savings, and fuel efficiency through the elimination of the wires and enables new sensor technologies to be integrated into vehicles, which would otherwise be impossible using wired means such as Intelligent Tire. The close interaction of communication with control systems, strict reliability, energy efficiency, and delay requirements in such a harsh environment that contains a large number of reflectors that operate at extreme temperatures are distinguishing properties of this network. In this paper, we investigate optimal power control, rate adaptation, and scheduling for an ultrawideband-based IVWSN for one-electronic-control-unit (ECU) and multiple-ECU cases. For the one-ECU case, we show that the optimal rate and power allocation is independent of the optimal scheduling algorithm. We prove the NP-hardness of the scheduling problem and formulate the optimal solution as a mixed-integer linear programming (MILP) problem. We then propose a 2-approximation algorithm, which is the smallest period into the shortest subframe first (SSF) algorithm. For the multiple-ECU case, where the concurrent transmission of links is possible, we formulate the optimal power control as a geometric-programming problem and optimal scheduling problem as an MILP problem where the number of variables is exponential in the number of links. We then propose a heuristic algorithm-the maximum-utility-based concurrency allowance algorithm-based on the idea of significantly improving the performance of the SSF algorithm in the existence of multiple ECUs by determining the sets of maximum utility.
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    Energy and delay constrained maximum adaptive schedule for wireless networked control systems
    (IEEE-Inst Electrical Electronics Engineers Inc, 2015) N/A; Department of Electrical and Electronics Engineering; Şadi, Yalçın; Ergen, Sinem Çöleri; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; 246556; 7211
    Communication system design for wireless networked control systems (WNCSs) is very challenging since the strict timing and reliability requirements of control systems should be met by the wireless communication systems that introduce non-zero packet error probability and non-zero delay at all times. Particularly, the scheduling algorithms for WNCSs should be designed to provide maximum level of adaptivity accommodating packet losses and changes in network topology while exploiting periodic nature of the sensor node transmissions. Creating such a schedule has been previously studied for an Ultra Wide Band (UWB) based WNCS. in this paper, we extend the joint optimization problem of power control, rate adaptation and scheduling with the objective of providing maximum adaptivity for general WNCSs employing continuous rate transmission model in which Shannon's channel capacity formulation is used for the achievable transmission rate. Upon proving the NP-hardness of the problem, we provide a framework for the design of a heuristic algorithm for scheduling and propose an optimal polynomial time algorithm for the power control and rate adaptation problem following the derivation of the optimality conditions. We demonstrate via extensive simulations that the proposed algorithms outperform the existing algorithms with performance close to optimal solution and average runtime admissible for practical WNCSs.
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    Minimum energy data transmission for wireless networked control systems
    (Ieee-Inst Electrical Electronics Engineers Inc, 2014) Park, Pangun; N/A; Department of Electrical and Electronics Engineering; Şadi, Yalçın; Ergen, Sinem Çöleri; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; 246556; 7211
    The communication protocol design for wireless networked control systems brings the additional challenge of providing the guaranteed stability of the closed-loop control system compared to traditional wireless sensor networks. In this paper, we provide a framework for the joint optimization of controller and communication systems encompassing efficient abstractions of both systems. The objective of the optimization problem is to minimize the power consumption of the communication system due to the limited lifetime of the battery-operated wireless nodes. The constraints of the problem are the schedulability and maximum transmit power restrictions of the communication system, and the reliability and delay requirements of the control system to guarantee its stability. The formulation comprises communication system parameters including transmission power, rate and scheduling, and control system parameters including sampling period. The resulting problem is a Mixed-Integer Programming problem. However, analyzing the optimality conditions on the variables of the problem allows us to reduce it to an Integer Programming problem for which we propose an efficient solution method based on its relaxation. Simulations demonstrate that the proposed method performs very close to optimal and much better than the traditional separate design of these systems.
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    Delay constrained energy minimization in UWB wireless networks
    (Institute of Electrical and Electronics Engineers (IEEE), 2013) N/A; Department of Electrical and Electronics Engineering; Şadi, Yalçın; Ergen, Sinem Çöleri; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; 246556; 7211
    We study the optimal power control, rate adaptation and scheduling for energy minimization subject to delay, traffic demand, transmit power and SNIR constraints in Ultra-Wideband wireless networks. We first show that power control is not required for delay constrained energy minimization. We then formulate optimal scheduling problem as an exponential size Linear Programming (LP) problem for which we propose the Pricing Minimization based Column Generation Method (PMCGM). PM-CGM decomposes the exponential size LP problem into two sub-problems Restricted Master Problem (RMP) and Pricing Problem (PP) and solves it iteratively. We solve the corresponding delay minimization problem for the initialization of the RMP and propose a pricing minimization based polynomial time algorithm to solve the non-linear integer PP formulation. Simulations illustrate that PM-CGM algorithm decreases the runtime required to solve the large scale LP problem considerably while performing very close-to-optimal for different network scenarios.
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    Minimum length scheduling with packet traffic demands in wireless ad hoc networks
    (Ieee-Inst Electrical Electronics Engineers Inc, 2014) N/A; N/A; Department of Electrical and Electronics Engineering; Şadi, Yalçın; Ergen, Sinem Çöleri; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 7211
    Traditional approach to the minimum length scheduling problem ignores the packet level details of transmission protocols, meaning that a packet transmission can be divided into several data chunks each of which is transmitted at a different rate due to the difference in the set of concurrently transmitting nodes. This solution requires including packet headers for each data chunk resulting in both an increase in the system overhead and underutilization of the time slots. In this paper, we extend the previous works on minimum length scheduling by considering the transmission of the packets of arbitrary sizes in the time slots of arbitrary lengths. Given the packet traffic demands on the links, we formulate the joint optimization of the power control, rate adaptation and scheduling for minimizing the schedule length of a wireless ad hoc network and demonstrate the hardness of this problem. Upon solving the power control and rate adaptation problem separately, we formulate the scheduling problem as an integer programming (IP) problem where the number of variables is exponential in the number of the links. In order to solve this large-scale IP problem fast and efficiently, we propose Branch and Price Method and Column Generation Method based heuristic algorithms.
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    Effects of MGS fragmentation, slice mode and extraction strategies on the performance of SVC with medium-grained scalability
    (IEEE, 2010) N/A; N/A; Department of Electrical and Electronics Engineering; Görkemli, Burak; Şadi, Yalçın; Tekalp, Ahmet Murat; PhD Student; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 26207
    This paper presents a comparison of a wide set of MGS fragmentation configurations of SVC in terms of their PSNR performance, with the slice mode on or off, using multiple extraction methods. We also propose a priority-based hierarchical extraction method which outperforms other extraction schemes for most MGS configurations. Experimental results show that splitting the MGS layer into more than five fragments, when the slice mode is on, may result in noticeable decrease in the average PSNR. It is also observed that for videos with large key frame enhancement NAL units, MGS fragmentation and/or slice mode have positive impact on the PSNR of the extracted video at low bitrates. While using slice mode without MGS fragmentation may improve the PSNR performance at low rates, it may result in uneven video quality within frames due to varying quality of slices. Therefore, we recommend combined use of up to five MGS fragments and slice mode, especially for low bitrate video applications.
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    Optimal power control and rate adaptation for ultra-reliable M2M control applications
    (IEEE, 2015) Department of Electrical and Electronics Engineering; N/A; N/A; Ergen, Sinem Çöleri; Şadi, Yalçın; Farayev, Bakhtiyar; Faculty Member; PhD Student; PhD Student; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 7211; N/A; N/A
    The main challenge of ultra-reliable machine-to-machine (M2M) control applications is to meet the stringent timing and reliability requirements of control systems, despite the adverse properties of wireless communication for delay and packet errors, and limited battery resources of the sensor nodes. Since the transmission delay and energy consumption of a sensor node are determined by the transmission power and rate of that sensor node and the concurrently transmitting nodes, the transmission schedule should be optimized jointly with the transmission power and rate of the sensor nodes. Previously, it has been shown that the optimization of power control and rate adaptation for each node subset can be separately formulated, solved and then used in the scheduling algorithm in the optimal solution of the joint optimization of power control, rate adaptation and scheduling problem. However, the power control and rate adaptation problem has been only formulated and solved for continuous rate transmission model, in which Shannon's capacity formulation for an Additive White Gaussian Noise (AWGN) wireless channel is used in the calculation of the maximum achievable rate as a function of Signal-to-Interference-plus-Noise Ratio (SINR). In this paper, we formulate the power control and rate adaptation problem with the objective of minimizing the time required for the concurrent transmission of a set of sensor nodes while satisfying their transmission delay, reliability and energy consumption requirements based on the more realistic discrete rate transmission model, in which only a finite set of transmit rates are supported. We propose a polynomial time algorithm to solve this problem and prove the optimality of the proposed algorithm. We then combine it with the previously proposed scheduling algorithms and demonstrate its close to optimal performance via extensive simulations. © 2015 IEEE.
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    Joint optimization of communication and controller components of wireless networked control systems
    (IEEE, 2015) Department of Electrical and Electronics Engineering; N/A; Ergen, Sinem Çöleri; Şadi, Yalçın; Faculty Member; PhD Student; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; 7211; N/A
    Designing communication system for wireless networked control systems requires overcoming the additional challenge of maintaining a guaranteed performance for the control system in the presence of wireless network induced imperfections including packet error, delay, sampling and quantization errors compared to traditional wireless sensor networks. The joint optimization of controller and communication systems encompassing efficient abstractions of each system and taking into account all wireless induced imperfections, the parameters of the wireless communication system including the transmission power, rate and scheduling and the parameters of the control system including the sampling period has been studied for the objective of minimizing the average power consumption of the network and the MQAM modulation scheme. In this paper, we extend the joint optimization problem for a generalized power cost function that represents many power-related objectives including minimization of total power consumption of the network and minimization of maximum power consumption among the nodes in the network and for any modulation scheme that satisfies certain properties including MQAM and MFSK. The optimization problem is formulated as a Mixed-Integer Programming problem thus difficult to solve for the global optimum. However, upon determining the optimality conditions for the optimization variables, the problem reduces to an Integer Programming problem for which we propose an optimal fast enumeration algorithm. Simulations demonstrate that the proposed optimal solution method outperforms the traditional separate design of control and communication systems. © 2015 IEEE.
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    Joint optimization of wireless network energy consumption and control system performance in wireless networked control systems
    (IEEE-Inst Electrical Electronics Engineers Inc, 2017) Department of Electrical and Electronics Engineering; N/A; Ergen, Sinem Çöleri; Şadi, Yalçın; Faculty Member; PhD Student; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; 7211; 246556
    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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    Fast scheduling for delay minimization in UWB wireless networks
    (IEEE-inst Electrical Electronics Engineers inc, 2012) N/A; Department of Electrical and Electronics Engineering; Şadi, Yalçın; Ergen, Sinem Çöleri; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; 246556; 7211
    We study the optimal scheduling problem for delay minimization subject to traffic demand, transmit power and Signal-to-Noise-plus-interference Ratio (SNIR) constraints in rate-controlled Ultra-Wideband (UWB) wireless networks. We first formulate the Linear Programming (LP) problem where the number of variables is exponential in the number of the links. We then propose the heuristic algorithm called Exclusion Region and Utility Maximization based Column Generation Method (EXUM-CGM) to solve the problem rapidly and efficiently. in EXUM-CGM, we decompose the large scale problem into two sub-problems, Restricted Master Problem (RMP) and Pricing Problem (PP). We adapt the exclusion region concept commonly used in UWB systems to the initialization of the RMP. Since the PP formulation is a non-linear integer programming problem, we propose a heuristic algorithm based on utility maximization. Through the simulations, we show that EXUM-CGM decreases the runtime of the exponential LP problem significantly while achieving very close-to-optimal solutions.