Researcher:
Bağcı, Kadir Tolga

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Kadir Tolga

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Bağcı

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Bağcı, Kadir Tolga

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2010 - 201914

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Now showing 1 - 10 of 14
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    End-to-end service-level management framework over multi-domain software defined networks
    (Institute of Electrical and Electronics Engineers (IEEE), 2016) N/A; N/A; N/A; Department of Electrical and Electronics Engineering; Bağcı, Kadir Tolga; Nacaklı, Selin; Şahin, Kemal Emrecan; Tekalp, Ahmet Murat; PhD Student; PhD Student; Master Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; 26207
    We introduce a distributed, dynamic, end-to-end (E2E) service-level management framework over a multi-domain SDN in order to enable end users to negotiate with their service providers a level of service according to their needs and budget. In this framework, the service provider offers multiple levels of service and allocates network resources to each user to satisfy specific service level requests in a fair manner. To this effect, controllers of different domains negotiate with each other to satisfy the service level parameters of service requests, where functions that manage E2E services collaborate with functions that manage network resources of respective domains. The proposed framework and procedures have been verified over a newly developed large-scale multi-domain SDN emulation environment./ Öz: Çok-alanlı yazılım tanımlı ağlarda (YTA), son kul- lanıcıların servis sağlayıcıları ile belirli bir servis kalitesi için uzlaşmalarını sağlamak amacıyla da gıtık, dinamik ve uçtan uca servis kalitesi yönetimi önermekteyiz. Bu yapıda servis saglayıcıları birçok servis seviyesi önermekte ve ağ kaynaklarını kullanıcılara adil bir ¸sekilde bölü¸stürmektedir. Bu amaçla, uçtan uca servisleri ve her bir alanın kaynaklarını yöneten modüller işbirligi yaparak farklı alanların ağ yöneticilerinin servis istek- lerinin kısıtlarını sağlayacak şekilde birbirleri ile uzlaşmalarına olanak sağlamaktadır. Önerilen yapı ve modüller yeni geliştirilmiş büyük ölçekli çok-alanlı bir YTA’da test edilmiştir.
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    Openqos: an openflow controller design for multimedia delivery with end-to-end quality of service over software-defined networks
    (IEEE, 2012) Department of Electrical and Electronics Engineering; N/A; N/A; N/A; Tekalp, Ahmet Murat; Eğilmez, Hilmi Enes; Dane, Said Tahsin; Bağcı, Kadir Tolga; Faculty Member; Master Student; Master Student; PhD Student; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 26207; N/A; N/A; N/A
    OpenFlow is a Software Defined Networking (SDN) paradigm that decouples control and data forwarding layers of routing. In this paper, we propose OpenQoS, which is a novel OpenFlow controller design for multimedia delivery with end-to-end Quality of Service (QoS) support. Our approach is based on QoS routing where the routes of multimedia traffic are optimized dynamically to fulfill the required QoS. We measure performance of OpenQoS over a real test network and compare it with the performance of the current state-of-the-art, HTTP-based multi-bitrate adaptive streaming. Our experimental results show that OpenQoS can guarantee seamless video delivery with little or no video artifacts experienced by the end-users. Moreover, unlike current QoS architectures, in OpenQoS the guaranteed service is handled without having adverse effects on other types of traffic in the network.
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    SDN-enabled distributed open exchange: dynamic QoS-path optimization in multi-operator services
    (Elsevier, 2019) N/A; Department of Electrical and Electronics Engineering; Bağcı, Kadir Tolga; Tekalp, Ahmet Murat; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 26207
    We propose an SDN-enabled distributed open exchange framework for dynamic optimization of end-to-end (E2E) quality of service (QoS) paths over multi-operator networks, which enables individual network service providers (NSP) to offer inter-operator services with E2E QoS guarantees while allowing each NSP to manage their own network resources. Different from the state of the art, there are no physical Internet exchange points in the proposed framework and NSPs are assumed to have direct inter-connections. In the proposed SDN-enabled "virtual" open exchange, the SON controllers of all NSPs directly communicate with each other to advertise a set of QoS-enabled paths across their own network with ask prices, and each NSPs dynamically selects the best E2E price-performance path for its customers by bidding on a subset of these advertised paths, and form E2E paths by concatenating them. The main contributions of this paper are a distributed open exchange framework and a distributed procedure for E2E path computation by collaboration between SDN controllers of multiple NSPs, which is coordinated by the SDN controller of the NSP in which the managed service request originates. The proposed procedure has been verified over a multi-operator SDN environment, emulated by using the Mininet, which includes a controller-to-controller messaging protocol for provisioning multi-operator video services with E2E QoS. (C) 2019 Published by Elsevier B.V.
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    Distributed-collaborative managed dash video services
    (Ieee, 2017) N/A; N/A; N/A; Department of Electrical and Electronics Engineering; Şahin, Kemal Emrecan; Bağcı, Kadir Tolga; Tekalp, Ahmet Murat; Master 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
    We propose a new distributed-collaborative managed DASH video service architecture over software defined networks (SDN) that enables fair and stable video quality to heterogeneous resolution clients. The proposed service is managed by the video service provider (VSP) in collaboration with the network service provider (NSP), where groups of clients sharing a network slice with a reserved throughput collaborate with each other to compute their own fair-share bitrates. Our novel distributed service architecture allows each client to share its buffer status with other clients in the same collaboration group so that each client can estimate a group-buffer-status aware fair-share bitrate, enforce this rate by TCP receive-window size control over a network slice reserved for the group, and perform application-level DASH video rate adaptation that is consistent with this enforced fair bitrate. Experimental results show that the proposed collaborative video service outperforms the traditional competitive DASH clients in terms of (i) minimizing quality fluctuations per client, (ii) fairness among heterogeneous DASH clients, and (iii) maximizing the total goodput of reserved network slice.
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    Virtualized cloud video services
    (Institute of Electrical and Electronics Engineers (IEEE), 2017) N/A; N/A; N/A; Department of Electrical and Electronics Engineering; Nacaklı, Selin; Şahin, Kemal Emrecan; Bağcı, Kadir Tolga; Tekalp, Ahmet Murat; PhD Student; Master Student; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; 26207
    We propose new architectures for collaborative video services using software defined networks (SDN) and cloud computing technologies. In the proposed architectures, the video service provider (VSP) is configured as a cloud service. The network service provider (NSP) employs SDN as a cloud service, consisting of a controller cloud and multiple edge network clouds. The proposed centralized and distributed collaborative cloud video services overcome quality of experience (QoE) fluctuations per flow and unfairness between multiple DASH clients employing TCP receive window adaptation over a network slice with reserved capacity as we show that quality of service (QoS) reservation alone is not sufficient to supply fair and steady QoE to all clients. In the centralized approach, the fair-share bitrate of each client is calculated by the traffic engineering module of the NSP, while in the distributed approach the clients collaborate with each other to calculate their own fair shares. Experimental results show that both collaboration architectures perform better than the competitive approach using standard TCP.
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    Distributed-collaborative managed dash video services
    (Institute of Electrical and Electronics Engineers (IEEE), 2017) N/A; N/A; Department of Electrical and Electronics Engineering; Şahin, Kemal Emrecan; Bağcı, Kadir Tolga; Tekalp, Ahmet Murat; Master 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
    We propose a new distributed-collaborative managed DASH video service architecture over software defined networks (SDN) that enables fair and stable video quality to heterogeneous resolution clients. The proposed service is managed by the video service provider (VSP) in collaboration with the network service provider (NSP), where groups of clients sharing a network slice with a reserved throughput collaborate with each other to compute their own fair-share bitrates. Our novel distributed service architecture allows each client to share its buffer status with other clients in the same collaboration group so that each client can estimate a group-buffer-status aware fair-share bitrate, enforce this rate by TCP receive-window size control over a network slice reserved for the group, and perform application-level DASH video rate adaptation that is consistent with this enforced fair bitrate. Experimental results show that the proposed collaborative video service outperforms the traditional competitive DASH clients in terms of (i) minimizing quality fluctuations per client, (ii) fairness among heterogeneous DASH clients, and (iii) maximizing the total goodput of reserved network slice.
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    Dynamic end-To-end service-level negotiation over multi-domain software defined networks
    (Institute of Electrical and Electronics Engineers (IEEE), 2016) N/A; N/A; N/A; Department of Electrical and Electronics Engineering; Bağcı, Kadir Tolga; Nacaklı, Selin; Şahin, Kemal Emrecan; Tekalp, Ahmet Murat; PhD Student; PhD Student; Master Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; 26207
    We introduce a dynamic end-To-end (E2E) servicelevel management framework, which enables quality of experience to end users and efficient and flexible management of network resources for service providers, over a multi-domain SDN. In the proposed fully-distributed E2E service management framework, controllers of different domains negotiate with each other for the service level parameters of a specific service request. The main contribution of this paper is an automated dynamic E2E service-level negotiation procedure, where functions that manage E2E services can collaborate with functions that manage network resources of respective domains. The proposed framework and procedures have been verified over a large-scale multi-domain SDN emulation environment.
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    Dynamic resource allocation by batch optimization for value-added video services over SDN
    (IEEE-Inst Electrical Electronics Engineers Inc, 2018) N/A; Department of Electrical and Electronics Engineering; Bağcı, Kadir Tolga; Tekalp, Ahmet Murat; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 26207
    We propose a video service architecture and a novel resource allocation optimization framework to enable network service providers (NSP) to offer value-added video services (VAVS) over software-defined networking including different service levels, service-level awareness of users, and associated business models. To this effect, we introduce a new batch-optimization framework, where resource (path, bitrate, and admission control) allocations for a small group of flows (consisting of new service requests and some existing ones) are performed simultaneously as the number of new service requests and network conditions vary. The optimization problem becomes NP-complete when path computations are jointly (re-)optimized as a group in order to accommodate all service requests to the extent possible, to best utilize entire network resources in a fair manner, and maximize network service provider's revenue. In order to compute dynamic resource allocations online, we propose a heuristic group-constrained-shortest path procedure that aims for a fair allocation of resources among a group of requests with the same service level, while maximizing the total NSP revenue. Experimental results demonstrate the feasibility of the proposed method for possible deployment by NSP to offer future VAVS, and that the proposed solution is close to the optimal solution, which is approximately computed using a divide-and conquer strategy, for varying network size and traffic load conditions. In particular, we show that processing service requests in batches significantly improves total revenue and fairness in congested mode of operation.
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    Queue-allocation optimization for adaptive video streaming over software defined networks with multiple service-levels
    (Institute of Electrical and Electronics Engineers (IEEE), 2016) N/A; N/A; Department of Electrical and Electronics Engineering; Bağcı, Kadir Tolga; Şahin, Kemal Emrecan; Tekalp, Ahmet Murat; PhD Student; Master 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
    Internet service providers (ISP) are deploying software defined networking (SDN), which enables them to better utilize their resources and increase their revenues by offering on-demand differentiated services. In particular, SDN makes provisioning of dynamically managed video services with multiple levels of service viable, since the controller has complete vision of network resources and can change flow paths dynamically by continuously optimizing routes for each flow according to network state. This paper proposes a new method for flow-path computation by queue allocation with the objective of maximizing ISP revenues under per-flow service-level constraints. We formulate the optimization problem and implement its solution in the path computation unit of an SDN controller. Our experiments support that customers requesting improved quality video service receive significantly better QoE compared to best effort services to justify their paying extra for these services.
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    Adaptive stereoscopic 3D video streaming
    (Ieee, 2010) N/A; N/A; Department of Electrical and Electronics Engineering; Gürler, Cihat Göktuğ; Bağcı, Kadir Tolga; 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 comparative analysis of scalable stereoscopic video coding strategies for adaptive streaming. In particular, we compare scalable simulcast coding of both views using SVC with scalable coding of one view with SVC and non-scalable coding of the other view using H. 264/AVC, and benchmark them against non-scalable dependent coding of both views using the MVC. All of these coding options allow both symmetric and asymmetric coding of stereo videos. In addition, we propose a lightweight and periodic feedback mechanism for rate estimation and a strategy to adapt the total stereo source rate using SNR scalability option of SVC, while minimizing the loss rate of non-discardable packets. Experimental results show that dynamic rate scaling of only one view provides sufficient rate adaptation capability and better overall compression efficiency compared to scaling both of the views.