Browsing by Subject "Frequency allocation"

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    Bant genişliği kısıtı altında videonun en iyi iletimi
    (IEEE, 2006-04) Gürses, E.; Akar, G. B.; Akar, Nail
    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 on time delivery probability of video frames in the transmission window while conforming to network-imposed available bandwidth constraints. The effectiveness of the proposed approach is validated by comparing the results with theoretically obtained rate-distortion curves corresponding to the optimal policies by using the distortion model in [2] © 2006 IEEE.
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    BYYO Radyosu’ndan Radyo ILEF’e: Ankara’da RTÜK tarafından frekans tahsis edilmiş tek üniversite radyosu
    (Bilkent University, 2022) Kayaş, Defne; Çınar, İrem; Özbek, Naz; Purtaş, Kayra; Sökmen, Doğa
    Ankara Üniversitesi Radyosu olarak bilinen Radyo İlef, ilk olarak 1982 yılında BYYO Radyosu bünyesinde kapalı devre yayınları yapmıştır. Kuruluşundan günümüze kadar farklı adlarla radyo tarihinde yerini alan Radyo İlef, Ankara’nın ilk üniversite radyosudur. Bu doğrultuda da radyo eğitiminde teorik bilgilerin yanında uygulamalı eğitimin önemli olduğunu savunmuşlardır. Havadan yayına ise 1994 yılında “Radyo Radyo” adıyla geçmişlerdir. Süreç boyunca birkaç kez kapatılmasına rağmen radyo hala günümüzde de yayınlarına devam etmektedir. Ayrıca RTÜK tarafından Ankara’da frekans tahsis edilmiş tek üniversite radyosudur. Yayıncılık anlayışlarında eskisine göre farklılıklar olan Radyo İlef, özgün müzikleri (easy listening tarzı) ve reklamsız yayınlarıyla pek çok farklı ülkeden oluşan büyük bir dinleyici kitlesine sahiptir. Radyonun kuruluş aşamasında rol alan Halil Güven ile röportaj yapılması da araştırma adına önem arz etmektedir.
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    Computer aided frequency planning for the radio and TV broadcasts
    (Institute of Electrical and Electronics Engineers, 1996-06) Altıntaş, Ayhan; Ocalı, O.; Topçu, Satılmış; Tanyer, S. G.; Köymen, Hayrettin
    The frequency planning of the VHF and UHF broadcasts in Turkey is described. This planning is done with the aid of computer databases and digital terrain map. The frequency offset is applied whenever applicable to increase the channel capacity. The offset assignment is done through simulated annealing algorithm. The international rules and regulations concerning Turkey are also considered.
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    Durağan olmayan çok bileşenli boğucu sinyaller için yeni bir uyarlanır karışma çıkarıcı analizi
    (IEEE, 2005) Durak, L.; Arıkan, Orhan; Song, I.
    A novel adaptive short-time Fourier transform (STFT) implementation for the analysis of non-stationary multi-component jammer signals is introduced. The proposed time-frequency distribution is the fusion of optimum STFTs of individual signal components that are based on the recently introduced generalized time-bandwidth product (GTBP) definition. The GTBP optimal STFTs of the components are combined through thresholding and obtaining the individual component support images, which are related with the corresponding GTBP optimal STFTs.
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    MPLS automatic bandwidth allocation via adaptive hysteresis
    (Elsevier, 2010-11-29) Akar, N.; Toksöz, M. A.
    MPLS automatic bandwidth allocation (or provisioning) refers to the process of dynamically updating the bandwidth allocation of a label switched path on the basis of actual aggregate traffic demand on this path. Since bandwidth updates require signaling, it is common to limit the rate of updates to reduce signaling costs. In this article, we propose a model-free asynchronous adaptive hysteresis algorithm for MPLS automatic bandwidth allocation under bandwidth update rate constraints. We validate the effectiveness of the proposed approach by comparing it against existing schemes in (i) voice and (ii) data traffic scenarios. The proposed method can also be used in more general GMPLS networks.
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    Performance limits on ranging with cognitive radio
    (IEEE, 2009-06) Dardari, D.; Karisan, Yasir; Gezici, Sinan; D'Amico, A. A.; Mengali, U.
    Cognitive radio is a promising paradigm for efficient utilization of the radio spectrum due to its capability to sense environmental conditions and adapt its communication and localization features. In this paper, the theoretical limits on time-of-arrival estimation for cognitive radio localization systems are derived in the presence of interference. In addition, an optimal spectrum allocation strategy which provides the best ranging accuracy limits is proposed. The strategy accounts for the constraints from the sensed interference level as well as from the regulatory emission mask. Numerical results are presented to illustrate the improvements that can be achieved by the proposed approach. © 2009 IEEE.
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    A scheme for handling connectionless services in connection-oriented networks
    (The Institute of Electronics, Information and Communication Engineers, 1997-10-25) Abdelati, M.; Arikan, E.
    In this work we propose a pricing scheme which serves as an instrument for managing connectionless services in connection-oriented communication networks. The scheme is able to allocate network bandwidth in a Pareto-optimal way that maximizes the total surplus. The key idea is to decompose the service provision procedure among three separate parties whose interactions are governed by a set of competitive pricing mechanisms.
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    Theoretical limits on time delay estimation for ultra-wideband cognitive radios
    (IEEE, 2008-09) Gezici, Sinan; Celebi, H.; Arslan, H.; Poor, H. V.
    In this paper, theoretical limits on time delay estimation are studied for ultra-wideband (UWB) cognitive radio systems. For a generic UWB spectrum with dispersed bands, the Cramer-Rao lower bound (CRLB) is derived for unknown channel coefficients and carrier-frequency offsets (CFOs). Then, the effects of unknown channel coefficients and CFOs are investigated for linearly and non-linearly modulated training signals by obtaining specific CRLB expressions. It is shown that for linear modulations with a constant envelope, the effects of the unknown parameters can be mitigated. Finally, numerical results, which support the theoretical analysis, are presented. © 2008 IEEE.