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The research work I have been involved can be summarized into five threads of execution:
Broadband wireless networks provide ample opportunities for introducing novel services and user experiences based on multimedia anytime-anywhere. However, supporting multimedia applications and services over wireless networks is challenging due to constraints and heterogeneities such as formidable physical layer impairments, limited bandwidth, limited battery power, random time-varying fading effect, different protocols and standards, and stringent Quality-of-Service (QoS) requirements. In this thesis work, we propose to study and devise robust multimedia transmission schemes over wireless networks with QoS support, which currently represents one of the most challenging research problems in wireless communications. The main focus will be maximizing energy efficiency. Moreover, these schemes will be evaluated analytically, experimentally and via discrete-time event simulations in the proposed thesis study. This is also linked to my previous M.Sc. study [TH-1,2,3]. [TH0-0] Gürkan Gür, S. Bayhan, and F. Alagöz, "Hybrid Satellite-IEEE 802.16 System for Mobile Multimedia Delivery," International Journal of Satellite Communications & Networking - special issue on "Hybrid/Integrated Satellite-Terrestrial Networks" (accepted, to appear in 2010). [TH0-1] Gürkan Gür , F. Alagoz, and M.Abdel-Hafez, "A Novel Error Concealment Method for Images Using Watermarking in Error-Prone Channels," in Proc. 16th IEEE Int. Symposium on Personal Indoor and Mobile Radio Commun. (PIMRC’05), Berlin, DE, September 2005. [TH0-2] F. Alagoz, Gürkan Gür, and M.Abdel-Hafez, “Performance Study of An Image Restoration Algorithm for Bursty Mobile Satellite Channels,” Lecture Notes in Computer Science (LNCS), Springer-Verlag, Volume 3733, Nov. 2005, pp. 748 - 758. [TH0-3] Gürkan Gür, F. Alagoz, Y. Altug, and E. Anarim, “Image Error Concealment Using Watermarking with Subbands for Wireless Channels,” IEEE Communications Letters, March 2007. [TH0-4] Gürkan Gür, S. Bayhan, and F. Alagoz, “Transport Protocols and QoS for Wireless Multimedia," book chapter in the book Handbook of Research on Wireless Multimedia: Quality of Service and Solutions, IGI Group Inc.
I have worked as a visiting researcher and participated in RoSE Project on Multiple Description Coding at Department of Information Science and Engineering (DISI) of the University of Trento, ITALY in 2009. In iMedia Lab, we have implemented some server-side and client-side components for MDC based streaming using FFMPEG available under GPL license. The Robust Streaming Environment (RoSE)
Project has been started in order to be a catalyst of the activities
carried in DISI and other external partners on multimedia networks,
devices and services. RoSE is focused on: As just been described in the above RoSE mission
section, one of the objective of this project is the development of
a testbed for the experimentation of different IPTV services. The
first generic architecture that has been developed inside our
project is focused on one of the most common problems that nowadays
the multimedia servers have to handle: the efficient support of
heterogenous clients (with different hardware and different
computational power) on different typology networks and conditions.
The generic architectural view of RoSE is depicted in figure below.
INTEGRATED BROADBAND WIRELESS NETWORKING THREAD (TH2): I also conduct research on next-generation wireless systems, mainly broadband multi-layered aerial networks and terrestrial systems, namely, WiMAX and lately 3G LTE. I have done some work regarding cross-layer [TH2-1] M. Abdel-Hafez, Gürkan Gür, and F. Alagoz, "Exploring the Issues of TCP over Satellite IP Networks," UAE Forum in Telecommunication Research 2006 (FTR2006), May 2006, Sharjah, United Arab Emirates. [TH2-2] Suzan Bayhan, Gürkan Gür , Fatih Alagoz, “Adaptive Routing Protocol for QoS in Two-Layered Satellite IP Networks,” in Proc. 2nd International Workshop in Satellite and Space Communications (IWSSC06), September 14-15 2006, Madrid, Spain. [TH2-3] Suzan Bayhan, Gürkan Gür, Fatih Alagoz, “VoIP Performance on NGEO Satellite IP Networks with On-board Processing Capabilities”, in Proc. 7th IEEE International Symposium on Computer Networks (ISCN06), June 16-18 2006, İstanbul, Turkey. [TH2-4] Suzan Bayhan, Gürkan Gür, and F. Alagoz, “Performance of Delay-Sensitive Traffic in Multi-layered Satellite IP Networks with On-board Processing Capability”, Wiley’s International Journal of Communication Systems,vol. 20, no. 12, pp. 1367-1389, Dec. 2007. [TH2-5] Gürkan Gür, S. Bayhan, F. Alagoz and A. Jamalipour, "On the Use of WiMAX as the Terrestrial Segment for DVB-SH Networks," to be presented in4th International Workshop on Satellite an Space Communications 2008 (IWSSC 2008), Toulouse, France, 2008. [TH2-6] Gürkan Gür, F. Alagoz, and T. Tugcu, "Link Adaptation Mechanisms in Wireless MAN," book chapter in the book Mobile WiMAX: Toward Broadband Wireless Metropolitan Area Networks, Auerbach Publications, CRC Press, 2007. [TH2-7] M. S. Kuran, Gürkan Gür, T. Tugcu, and F. Alagoz, “Cross-layer Routing-scheduling in IEEE 802.16 Mesh Networks," First International Conference on MOBILe Wireless MiddleWARE, Operating Systems, and Applications (MOBILWARE 2008), Innsbruck, Austria, Feb. 2008. [TH2-8] S. Kuran, Gürkan Gür, T. Tugcu, and F. Alagoz, "Applications of Cross-Layer Paradigm for Improving the Performance of WiMAX," accepted to IEEE Wireless Communications Magazine, 2010.
In 2007, I was involved in a joint research project to develop machine learning based location estimation scheme using RSS for cellular systems. The outcome scheme was embedded in a live commercial product. This project was related to M.Sc. thesis of graduate student Onur Türkyılmaz. His thesis work (supervised by Dr. Alagöz) has been one of the recipients of the 2009 Dr. Akin Cakmakci The Best M.Sc. Thesis Applied in the Industry Award in 2010. [TH3-1] Onur Turkyilmaz, F. Alagoz, Gürkan Gür, and T. Tugcu, "Environment Aware Location Estimation for Cellular Networks," EURASIP Journal on Advances in Signal Processing,vol. 2008, Article ID 276456, 9 pages, 2008. doi:10.1155/2008/276456 [TH3-2] Metin Barut, Ozgun Bayrak, Cagri Temizyurek, Onur Turkyilmaz, and Gürkan Gür , " A Novel Mobile Positioning Algorithm Based on Environment Estimation," 4th Workshop on Positioning, Navigation and Communication 2007 (WPNC'07), Hannover, Germany, March 2007.
The proliferation of wireless technologies has created a new dimension in the spectrum domain; mainly spectrum management and utilization. Because of the excessive demand for the radio spectrum, frequency bands are allocated not for just an application but for a variety of applications. Nevertheless, there still seems to be spectrum scarcity. Per contra, the research studies have shown that the spectrum utilization is very low in some certain bands, which leads to the conclusion that there is a problem with spectrum management and allocation not the spectrum itself. Thus, to combat the overcrowding and inefficient spectrum usage, the ideas on a more “clever” spectrum usage have led to the dynamic spectrum access (DSA) concepts. Moreover, the interoperability of the devices using a variety of access technologies is another driving force for more clever radios. The automatic upload and reconfiguration of the radio devices rather than hardware-based reconfiguration is essential especially in emergency communications. The so-called "smart radios" or "cognitive radios" aim to address all these issues. I am also conducting research on cognitive radio networks. We have a big related research group in our department: WiCo (WiMax Networks & Cognitive Radio) group. [TH4-1] Gürkan Gür, Suzan Bayhan, and F. Alagoz, "Cognitive Femtocell Networks: An Overlay Architecture for Localized Dynamic Spectrum Access," submitted to IEEE Wireless Communications Magazine-Special Issue on Dynamic Spectrum Management in Wireless Networks, 2010. [TH4-2] Gürkan Gür, Ö. Kafalı, A. Günay, and Suzan Bayhan, "C2ONAN: A Commitment-Based Multiagent Model for Cellular Cognitive Radio Networks," submitted to IEEE Systems Journal-Special Issue on Broadband Access Networks, 2010. [TH4-3] Suzan Bayhan, Gürkan Gür , and F. Alagoz, "High Altitude Platform (HAP) Driven Smart Radios: A Novel Concept," in Proc. 3rd International Workshop on Satellite an Space Communications 2007 (IWSSC 2007), Salzburg, Austria, Sept. 13-14 2007. [TH4-4] Suzan Bayhan, Gürkan Gür , and F. Alagoz, "Satellite Assisted Spectrum Agility," in Proc. 2007 Military Communications Conference (MILCOM2007), Orlando, Florida, USA, Oct. 29-31 2007. |
