Browsing by Author "Akar, Nail"
Now showing items 1-20 of 39
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Analysis of an Adaptive Modulation and Coding scheme with HARQ for TCP traffic
Öztürk, Onur; Akar, Nail (IEEE, 2015-04)In this paper, we analyze the aggregate TCP throughput performance of a wireless link utilizing Active Queue Management (AQM) and an Adaptive Modulation and Coding (AMC) scheme with Hybrid ARQ (HARQ) based on the probability ... -
Analysis of continuous feedback Markov fluid queues and its applications to modeling Optical Burst Switching
Yazıcı, Mehmet Akif; Akar, Nail (IEEE, 2013)Optical Burst Switching (OBS) has been proposed as a candidate technology for the next-generation Internet. In OBS, packets are assembled into a burst, and a burst control packet is sent in advance to inform and reserve ... -
Analytical model of asynchronous shared-per-wavelength multi-fiber optical switch
Akar, Nail; Raffaelli, C.; Savi, M. (IEEE, 2011)In this paper, a buffer-less shared-per-wavelength optical switch is equipped with multi-fiber interfaces and operated in asynchronous context. An analytical model to evaluate loss performance is proposed using an approximate ... -
Bant genişliği kısıtı altında videonun en iyi iletimi
Gürses, E.; Akar, G. B.; Akar, Nail (IEEE, 2006-04)In this paper, we propose an optimal video streaming framework using retransmissions based on the theory of Markov Decision Processes (MDP). Using MDPs, we calculate average reward optimal policies so as to maximize the ... -
BISDN (Broadband integrated services digital network)
Ayanoğlu, E.; Akar, Nail (John Wiley & Sons, 2003)The subject of B‐ISDN came into being in the late 1980s, together with the concept of Asynchronous Transfer Mode (ATM). ATM is closely tied to high‐speed packet switching by means of specialized switches implemented in ... -
Capacity analysis of a PMR system with DAB downlink
Şengül, Ersin; Can, B.; Akar, Nail; İder, Yusuf Ziya; Köymen, Hayrettin (IEEE, 2003)Several trunked private mobile radio (PMR) systems have been designed over the last decade, most of which have symmetric downlink and uplink channel capacities. These systems may not be spectrally efficient in case of group ... -
Çok-akışlı eşler arası isteğe bağlı video sistemlerinin Markov zinciri tabanlı güvenilirlik modellemesi
Yazıcı, Mehmet Akif; Öztoprak, K.; Akar, Nail; Akar, G. B. (IEEE, 2008-04)Çok-akışlı eşler-arası video, gelecek nesil isteğe bağlı video sistemleri için kullanılmaya aday teknolojilerdendir. Çok-akışlı video sistemlerinin sorunlarından birisi, eş dalgalanması adı verilen, eşlerin ağla olan ... -
Differentiated ABR: a new architecture for flow control and service differentiation in optical burst switched networks
Akar, Nail; Boyraz, Hakan (IEEE, 2005)In this paper, we study a new control plane protocol, called Differentiated ABR (D-ABR), for flow control and service differentiation in optical burst switched networks. Using D-ABR, we show using simulations that the ... -
Discrete-time queueing model of age of information with multiple information sources
Akar, Nail; Doğan, Ozancan (IEEE, 2021-01-22)Information freshness in IoT-based status update systems has recently been studied through the Age of Information (AoI) and Peak AoI (PAoI) performance metrics. In this article, we study a discrete-time server arising in ... -
Disk scheduling with shortest cumulative access time first algorithms
Akar, Nail; Tunç, Ç.; Gaertner, M.; Erden, F. (TÜBITAK, 2017)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 ... -
A distributed solution for air-time fairness in multi-rate WLANs
Yazıcı, Mehmet Akif; Akar, Nail (IEEE, 2013)WLANs employing IEEE802.11 standards suffer from a performance anomaly that drags down the fast nodes in the WLAN due to the slow nodes. Air time fairness has been proposed to battle this anomaly. We propose a novel ... -
Dynamic capacity management for voice over packet networks
Akar, Nail; Şahin, Cem (2003-06-07)In this paper, dynamic capacity management refers to the process of dynamically changing the capacity allocation (reservation) of a pseudo-wire established between two network end points. This process is based on certain ... -
Efficient transport of time-varying IP traffic in flexi-grid optical networks
Tunc, Çağlar; Akar, Nail (IEEE, 2014)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 ... -
Energy management for age of information control in solar-powered IoT end devices
Aydin, A. K.; Akar, Nail (Springer, 2021-07)In this paper, we propose several harvesting-aware energy management policies for solar-powered wireless IoT end devices that asynchronously send status updates for their surrounding environments to a network gateway device. ... -
Exact and approximate decoupling and noninteracting control problems
Akar, Nail (Bilkent University, 1989)In this thesis, we consider “exact” and “approximate” versions of the disturbance decoupling problem and the noninteracting control problem for linear, time-invariant systems. In the exact versions of these problems, we ... -
Exact calculation of blocking probabilities for bufferless optical burst switched links with partial wavelength conversion
Akar, Nail; Karasan, Ezhan (IEEE, 2004-10)In this paper, we study the blocking probabilities in a wavelength division multiplexing-based asynchronous bufferless optical burst switch equipped with a bank of tuneable wavelength converters that is shared per output ... -
Finding the exact distribution of (peak) age of information for queues of PH/PH/1/1 and M/PH/1/2 type
Akar, Nail; Doğan, Ozancan; Atay, Eray Ünsal (IEEE, 2020)Bufferless and single-buffer queueing systems have recently been shown to be effective in coping with escalated Age of Information (AoI) figures arising in single-source status update systems with large buffers and FCFS ... -
Impact of scalability in video transmission in promotion-capable differentiated services networks
Gürses, E.; Akar, G. B.; Akar, Nail (IEEE, 2002-09)Transmission of high quality video over the Internet faces many challenges including unpredictable packet loss characteristics of the current Internet and the heterogeneity of receivers in terms of their bandwidth and ... -
Joint cell muting and user scheduling in multicell networks with temporal fairness
Shahsavari, S.; Akar, Nail; Khalaj, B. H. (Hindawi Limited, 2018)A semicentralized joint cell muting and user scheduling scheme for interference coordination in a multicell network is proposed under two different temporal fairness criteria. In the proposed scheme, at a decision instant, ... -
Markov modulated periodic arrival process offered to an ATM multiplexer
Akar, Nail; Arıkan, Erdal (IEEE, 1993-11-12)When a superposition of on/off sources is offered to a deterministic server, a particular queueing system arises whose analysis has a significant role in ATM based networks. Periodic cell generation during active times is ...