Ahmet Cihat Toker

Rensselaer Polytechnic Institute, Troy, New York, United States

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Publications (9)1.03 Total impact

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    ABSTRACT: Quality of Experience (QoE) is the subjective judgment of the satisfaction an end user perceives from an application running over a given network topology and configuration. The information provided by end users regarding their QoE preferences, experience and feedback is invaluable in providing a service that meets with their mobile activity needs within various access networks. The PERIMETER project progresses the QoE thematic research area by taking end user-related QoE factors for end user-centric mobility experimentation, thus empowering them to always have a service in which their QoE is high. This paper will detail the components of the PERIMETER framework and the user centric scenario based process adopted to implement and develop such a framework. This paper provides an insight into the federated testbed infrastructure, testing methodology and tools, operating system and applications used in the project, thus demonstrating PERIMETER's innovative advances within the QoE end user domain.
    Testbeds and Research Infrastructures. Development of Networks and Communities - 6th International ICST Conference, TridentCom 2010, Berlin, Germany, May 18-20, 2010, Revised Selected Papers; 01/2010
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    ABSTRACT: Traditional approaches to resource sharing make the assumption that the cooperating entities are able to exchange performance related information. This is not a valid assumption if the entities belong to different operators. In such a scenario, cooperation decisions have to be taken under uncertainty. We present our dynamic inter operator resource sharing framework, in which we formulate the decision problem as a Partially Observable Markov Decision Problem(POMDP). We provide an exact solution POMDP and find the optimal borrowing threshold. We also propose a user-centric load measure that can be used independent of the underlying networking technology. We demonstrate our approach via a load balancing scenario for TCP traffic over 802.11g network.
    01/2010;
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    ABSTRACT: The possible leveraging of high deployment costs, and the possibility to increase revenue have also introduced the concept of network sharing between different operators. On the other hand, the realization of a user-centric paradigm in future heterogeneous wireless networks, which implies free and automatic choice among different available wireless and mobile access networks, will revolutionize future wireless networks. For this innovative concept to materialize a paradigm shift is required from a long-term contractual based service delivery to a short-term contractual and dynamic service delivery. In this paper we formulate and compare the network-centric resource allocation and and user-centric network selection problems in a multi-operator scenario using two different flavors of game theory, namely bargaining games (for network-centric resource sharing) and multi-attribute auctions (for user-centric interface selection). We also compare the contributed solutions to one another to investigate their performance in terms of efficient resource allocation, call blocking probability, and user satisfaction.
    Communications: Wireless in Developing Countries and Networks of the Future - Third IFIP TC 6 International Conference, WCITD 2010 and IFIP TC 6 International Conference, NF 2010, Held as Part of WCC 2010, Brisbane, Australia, September 20-23, 2010. Proceedings; 01/2010
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    ABSTRACT: Realtime resource sharing between operators is an efficient approach to deal with the ever increasing wireless traffic. Simple and closed form formulas relating cooperation terms to the network performance measures are needed, so that the operators can take cooperate/not cooperate decisions, and track the benefits/losses of sharing. Analytical solutions to resource sharing the among access networks of a single operator exist. However the fact that operators will not share network internal data calls for solutions that are separable from each other. In this paper we provide such a closed form formulation, validate it with simulations and propose a simple negotiation mechanism between two operators utilizing this model. This simple model can be extended to model more complex interactions between operators, interaction between more than two operators, or can be used to evaluate long term cooperation policies. Keywordsresource sharing-4G-performance modeling-cooperation-traffic engineering
    12/2009: pages 229-240;
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    ABSTRACT: The current trend in wireless communication networks involves the integration of different wireless access technologies into a single operator network. The possible leveraging of high deployment costs, and the possibility to increase revenue have also introduced the concept of network sharing between different operators. The problem of optimal allocation of bandwidth to multimedia applications over different wireless access networks, is augmented with the possibility of using the bandwidth of other operators who are willing to share bandwidth.We formulate the allocation of bandwidth within the operator network and distribution of excess bandwidth among operators as cooperative bargaining games. We provide distribution and allocation rules based on the Kalai-Smorodinsky Solution, and provide bandwidth offer algorithms based on these rules. We compare this integrated approach with the service and capacity based approaches in the literature.
    Proc. Int. Conf. Game Theory for Networks GameNets '09; 01/2009
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    S. Albayrak, M. Elkotob, A.C. Toker
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    ABSTRACT: We have designed a smart middleware and are working on implementing and deploying it as a landmark architectural piece run by nodes of the Future Internet. The middleware we propose aims as a main goal at making applications and services fully network-aware in the sense that they utilize network resources and tune their own demands based on what the underlying networks can offer. On the other hand, the smart middleware makes networks service aware in the sense that networks also adapt their configuration to service demands. Challenges of the Future Internet such as scalability, increased interoperability, and smart collaboration between engines are addressed by our middleware. Focusing on 3GPP networks including IP Multimedia Subsystem (IMS) networks, this paper presents the architectural design of our middleware and shows in two showcases how and why it is capable of addressing future challenges. Scenarios such as service and network-aware coordinated load balancing and ldquoalways-best-connectedrdquo as a service verify the merits of our smart middleware design.
    Communication Systems Software and Middleware and Workshops, 2008. COMSWARE 2008. 3rd International Conference on; 02/2008
  • S. Albayrak, K. Bur, A.C. Toker
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    ABSTRACT: The Internet, mobile telephony and portable computers let today's user meet novel applications provided by the service developers, who are motivated by the popular customer trends in technology. However, the supply-demand chain observed in telecommunications causes the complexity of both the user devices as well as the network to increase. The complexity is caused by the need to support quality of service, security and mobility for the new services throughout the heterogeneous communication network. These problems slow down the application development process significantly and cause the user demand not to be met in time. We believe that a new look at the network is necessary in order to address these issues. This article presents this new look, which we term network economy. It is a service-centric approach to next generation mobile networks, whereby the network is redefined as a collection of diverse resources. The aim of network economy is to optimise the allocation of these resources such that network efficiency is maximised. In order to achieve this objective, the intelligence level of the network is increased by decision engines, which continuously collect information from the network, classify and store it in a repository to be queried by their peers. The approach is accompanied by context-aware, self-organising user devices. Network economy provides a network-wide infrastructure to benefit users, service developers as well as network operators.
    Personal, Indoor and Mobile Radio Communications, 2007. PIMRC 2007. IEEE 18th International Symposium on; 10/2007
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    ABSTRACT: The widespread deployment of the IEEE 802.11 protocol has made it the de facto standard for wireless network access and allows Internet users to move freely (at least within a hotspot coverage). The convenience brought about by the IEEE 802.11 protocol is also accompanied by new technical challenges such as poor performance of the widely used transport protocol TCP due to the limited and varying bandwidth resources of the wireless medium. In this work, we seek to enhance efficiency of bandwidth usage for TCP over wireless links and improve TCP goodput. Our insight is that TCP acknowledgments can be spared on wireless links to save precious bandwidth resource of these links. We propose a simple technique that leverages the layer coordination between TCP and MAC to suppress TCP acknowledgments. Our technique is transparent to both TCP and MAC and does not require their modification or replacement.
    Communications, 2007. ICC '07. IEEE International Conference on; 07/2007
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    ABSTRACT: The increasing number of radio access technologies and the availability of multi-radio devices boost the need for novel resource allocation schemes in cellular networks. This paper uses a cooperative game theoretic approach for resource allocation at the network level, while utilizing simultaneous use of available radio interfaces at the device level. We model resource allocation management using the well known bankruptcy model and apply Kalai-Smorodinsky bargaining solution method to find a distribution rule, based on which we propose resource allocation and call admission control schemes. Performance analysis of our allocation and control schemes demonstrates significant improvements over previous approaches in terms of utilization of the available bandwidth and the number of call drops. We also study the performance of proposed approach for different operator policies. KeywordsWireless networks–Resource allocation–Game-theory
    Telecommunication Systems · 1.03 Impact Factor