Çağlar Tunç | Bilkent University (original) (raw)
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Papers by Çağlar Tunç
Turkish J. Electr. Eng. Comput. Sci., 2017
A new class of scheduling algorithms is proposed for disk drive scheduling. As opposed to choosin... more A new class of scheduling algorithms is proposed for disk drive scheduling. As opposed to choosing the request with the shortest access time in conventional shortest access time first (SATF) algorithms, we choose an ordered sequence of pending I/O requests at the scheduling instant with the shortest cumulative access time. Additionally, we introduce flexibility for forthcoming requests to alter the chosen sequence. Simulation results are provided to validate the effectiveness of the proposed disk scheduler. Throughput gains of 3% and above are shown to be attainable, although this occurs at the expense of increased computational complexity.
2014 22nd Signal Processing and Communications Applications Conference (SIU), Apr 1, 2014
Özetçe-Esnek (elastik)şebekeli optik aglarda frekans dilimi genişligi seçimi ile kastedilen, tale... more Özetçe-Esnek (elastik)şebekeli optik aglarda frekans dilimi genişligi seçimi ile kastedilen, talep edilen trafik durumuna göre, tahsis edilen frekans dilimi genişligini dinamik olarak güncellemektir. Bununla birlikte güncelleme sıklıgının artması, optik ag için bir yük oluşturacagından ötürü güncelleme sıklıgının genelde sınırlandırılması gereklidir. Bu makalede, trafik modelinden bagımsız olarak çalışan bir çevrimiçi frekans dilimi genişligi seçim mekanizması tanıtılmaktadır. Anahtar Kelimeler-Dinamik frekans dilimi tahsisi, Esnekşebekeli optik aglar, Trafik Mühendisligi, Trafik adaptasyonu Özet-Frequency slot width selection in flexi-grid optical networks refers to the process of online update of the slot width of the channel, according to time-varying traffic demands. Since slot width updates are associated with signaling costs, it is common to limit the rate of updates. In this article, we propose a modelfree hysteresis-based slot width selection algorithm for flexi-grid optical networks.
Photonic Network Communications, Aug 28, 2014
A spectrum slot is the frequency range allocated to a single channel within a flexible grid, and ... more A spectrum slot is the frequency range allocated to a single channel within a flexible grid, and its width needs to be an integer multiple of the so-called slot width granularity. The slot width of the spectrum slots to be used for an optical path in flexgrid optical networks can be adjusted in time to align with time-varying client traffic demand for both bandwidth and energy efficiency purposes. However, frequent adjustment of the slot width of optical paths places substantial signaling load on the control plane. In this paper, an online slot width adjustment mechanism is proposed for flexgrid optical networks under slot width update rate constraints in order to maintain the associated signaling load at acceptable levels. Real traffic traces are used to validate the effectiveness of the proposed mechanism. Keywords Flexgrid optical networks • Dynamic slot width adjustment • Elastic spectrum allocation • IP over optical architectures 1 Introduction Optical transport networks currently use Dense Wavelength Division Multiplexing-based (DWDM) transmission using the International Telecommunication Union (ITU) fixed frequency grid, which divides the optical spectrum range at the C-band (1,530-1,565 nm) into fixed 50-GHz spectrum slots [15,26]. In fixed-grid optical networks, the basic switching
Turkish J. Electr. Eng. Comput. Sci., 2017
A new class of scheduling algorithms is proposed for disk drive scheduling. As opposed to choosin... more A new class of scheduling algorithms is proposed for disk drive scheduling. As opposed to choosing the request with the shortest access time in conventional shortest access time first (SATF) algorithms, we choose an ordered sequence of pending I/O requests at the scheduling instant with the shortest cumulative access time. Additionally, we introduce flexibility for forthcoming requests to alter the chosen sequence. Simulation results are provided to validate the effectiveness of the proposed disk scheduler. Throughput gains of 3% and above are shown to be attainable, although this occurs at the expense of increased computational complexity.
2014 22nd Signal Processing and Communications Applications Conference (SIU), Apr 1, 2014
Özetçe-Esnek (elastik)şebekeli optik aglarda frekans dilimi genişligi seçimi ile kastedilen, tale... more Özetçe-Esnek (elastik)şebekeli optik aglarda frekans dilimi genişligi seçimi ile kastedilen, talep edilen trafik durumuna göre, tahsis edilen frekans dilimi genişligini dinamik olarak güncellemektir. Bununla birlikte güncelleme sıklıgının artması, optik ag için bir yük oluşturacagından ötürü güncelleme sıklıgının genelde sınırlandırılması gereklidir. Bu makalede, trafik modelinden bagımsız olarak çalışan bir çevrimiçi frekans dilimi genişligi seçim mekanizması tanıtılmaktadır. Anahtar Kelimeler-Dinamik frekans dilimi tahsisi, Esnekşebekeli optik aglar, Trafik Mühendisligi, Trafik adaptasyonu Özet-Frequency slot width selection in flexi-grid optical networks refers to the process of online update of the slot width of the channel, according to time-varying traffic demands. Since slot width updates are associated with signaling costs, it is common to limit the rate of updates. In this article, we propose a modelfree hysteresis-based slot width selection algorithm for flexi-grid optical networks.
Photonic Network Communications, Aug 28, 2014
A spectrum slot is the frequency range allocated to a single channel within a flexible grid, and ... more A spectrum slot is the frequency range allocated to a single channel within a flexible grid, and its width needs to be an integer multiple of the so-called slot width granularity. The slot width of the spectrum slots to be used for an optical path in flexgrid optical networks can be adjusted in time to align with time-varying client traffic demand for both bandwidth and energy efficiency purposes. However, frequent adjustment of the slot width of optical paths places substantial signaling load on the control plane. In this paper, an online slot width adjustment mechanism is proposed for flexgrid optical networks under slot width update rate constraints in order to maintain the associated signaling load at acceptable levels. Real traffic traces are used to validate the effectiveness of the proposed mechanism. Keywords Flexgrid optical networks • Dynamic slot width adjustment • Elastic spectrum allocation • IP over optical architectures 1 Introduction Optical transport networks currently use Dense Wavelength Division Multiplexing-based (DWDM) transmission using the International Telecommunication Union (ITU) fixed frequency grid, which divides the optical spectrum range at the C-band (1,530-1,565 nm) into fixed 50-GHz spectrum slots [15,26]. In fixed-grid optical networks, the basic switching