Elektronik ve Haberleşme Mühendisliği Bölümü

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A sequential coding approach for short length lt codes over awgn channel
(IEEE, 2017) Abdulkhaleq, Nadhir Ibrahim; Gazi, Orhan; 102896; Elektronik ve Haberleşme Mühendisliği
Luby Transform (LT) codes which can be considered as one of the first type of rate less codes are introduced to be an efficient erasure code. In such codes a fountain of encoded symbols is continuously transmitted until the successfully delivery of all the data packets. Whenever the receiver collects N noisy encoded symbols the decoding operation starts. Usually belief propagation (BP) algorithm is used to decipher the code and extract the k data symbols. In this paper, short length LT codes are generated using efficient sequential encoding approach (SEA) and performance measurements have been done over additive white Gaussian (AWGN) channel. This coding technique generates its degree in a repeated sequential manner which yields a mutual relation between adjacent codes that will be used in the decoding part. The decoding complexity of the proposed structure is similar to that of the Raptor codes. The simulation results show that the proposed approach has better performance in terms of error floor and successful decoding ratio when compared to LT codes using robust soliton distribution (RSD) and memory-based-RSD (MBRSD) even when supported by belief propagation-pattern recognition (BP-PR) technique.
Acoustic and Linguistic Properties of Turkish Whistle Language
(2018) Özaydın, Selma; 253019; Çankaya Meslek Yüksekokulu
This paper presents the acoustic and linguistic properties of Turkish Whistle Language. Whistle Language is a natural communication method usually used for far-distance interaction in some regions in the world. In a whistled speech, auditory features of spoken languages are transposed. Therefore, whistle languages carry some properties of vocal speech with its own vocabulary, grammar, phonology and prosodic features. There are a few places in the world using this whistled communication style and Kuskoy region in Turkey is one of them. Although there are some researches on Turkish Whistle Language, unfortunately there have been a limited number of scientific publications in the literature. On the other hand, the research results present very stunning results such as people can still continue articulating some words while whistling and there is a high understandability rate while communicating. Therefore, it is described as an incomplete form of Turkish Language. The research results also indicate that Turkish Whistle Language is a non-tonal language transposing formants and therefore it can be used to evaluate the formant changes in the transform of a language. These research results indicate many other valuable properties of Turkish whistle language. But, unfortunately there has not been a collective study combining all these properties. Besides, there are still unclear and conflicted points in the literature as can be implied in this paper. This study aims to bring together the research results to underline the distinct features of Turkish Whistle Language and to motivate researchers to go forward on this subject. The paper is mainly focused on acoustic and phonetic properties of Turkish Whistle Language. Historical or cultural based details are out of the scope of this study.
Analysis of delay factors for voice over WiMAX
(IEEE, 2008) Şafak, A.; Preveze, B.; 17573; Elektrik-Elektronik Mühendisliği
This paper presents the results of our computer simulation for delays experienced by voice packets over WiMAX 802.16e protocol running over an enterprise packet network connected to public internet. In the simulation we analyzed the effect of packet size, core network link speed, internet service provider link speed, wireless network link speed, wireless distance, base station range, and distance in internet parameters that effect the amount of delay in a WiMAX embedded IP network. In this study, all the delay parameters are fixed to their default values and current parameter values are changed so that the delay is varied between minimum and maximum values in uniformly distributed 100 steps and the delay is plotted in each step. Total fixed delays can be considered as minimum delay and variable delay corresponds to the maximum delay that can occur under the given conditions. All other fixed and variable delay parameters such as switching delays, packetization delays, contention delays and the delays caused by buffers etc. are also taken into account. The results indicate that among these delays WiMAX base station range and the number of base stations play the most decisive role.
Babinet's principle in the Fraunhofer diffraction by a finite thin wire
(Elsevier GMBH, 2011) Umul, Yusuf Ziya; 42699; Elektronik ve Haberleşme Mühendisliği
The scattered waves by a thin finite wire are evaluated by using the Rayleigh-Sommerfeld integral in the Fraunhofer approximation. The scattered fields by the complementary thin wire are also obtained with the aid of the Babinet's principle. The scattering integrals are evaluated directly. It is shown that Babinet's principle holds excellently for this problem. The scattered fields are examined numerically
Comparative Analysis of Early Studies on Turkish Whistle Language and a Case Study on Test Conditions
(2018) Özaydın, Selma; 253019; Çankaya Meslek Yüksekokulu
This paper examines the early studies on Turkish Whistle Language and it argues that they have some controversial results. The study considers these issues need to be discussed and searched again in terms of linguistic and phonetic form. Unfortunately, there are few research studies on Turkish whistle language and most of them were performed nearly fifty years ago despite the fact that this language still has been used in Kuskoy region. Therefore, the findings of these early research studies could give valuable information to start to a new research study on the subject. The first scientific study on Turkish Whistle language was performed by a French scientist R.G. Busnel with his multidisciplinary research team in 1967. Some of this research’s results were published in the book. A Turkish scientist O. Baskan also participated in Busnel’s research group and published a paper on TWsL in 1968. However, some assertions such as people having a tendency to understand the Turkish whistle language with three vowels and three consonants have not been in the research results of R.G. Busnel. In addition, a Turkish scientist D. Aksan in Turkey had performed another research at Kuskoy region with his own team. Their test methods were different from the previous ones. This paper analyzes these research results on a comparative basis and presents the common and conflicted issues to discuss the uncertain points. The comparative evaluation of these past research studies aims to highlight the controversial position of the results on Turkish Whistle Language. In this scope, this paper opens a discussion about the selection of test conditions for an acoustic and linguistic analysis of the Turkish whistle language.
Design of irregularly shaped patch antennas by using the multiport network model
(IEEE, 2008) Şener, Göker; Alatan, Lale; Kuzuoğlu, Mustafa; 17740; Elektrik-Elektronik Mühendisliği
Desıgnıng an off-road workıng lamp wıth leds
(2011) Çil, Celal Zaim; Yakışır, Burcu; Elektronik ve Haberleşme Mühendisliği
In this study a working lamp used on the offroad working machines and vehicles is designed by using the LED diodes instead of a halogen bulb. In the design, firs tly a LED array is determined and a proper driver circuit that can provid e the required optical power is designed, and the working lamp developed is tested under various conditions. The luminous output values of the designed LED working lamp are compared with those of a commercial working lamp, which uses a halogen bulb. It is evaluated that in automotive applications lamps using LEDs could be successfully utilized depending on the optical efficacy of the LED used, the designs of the LED driver and the reflecto
Developing growing hierarchical structures for decision making
(IEEE, 2007) Beldek, Ulaş; Leblebicioğlu, Kemal; 59950; Mekatronik Mühendisliği
This study is about developing a hierarchical approach for decision-making problems. The development is done on a representative decision-making problem. A hierarchical decision making approach which enables fusion of decisions of previous and current levels is proposed. The agents that determine the decisions at different hierarchy levels is accomplished by utilizing a genetic algorithm.
Diffraction Theory of Waves by Resistive Surfaces
(2010) Umul, Yusuf Ziya; Yalçın, Uğur; Elektronik ve Haberleşme Mühendisliği
Diffraction of scalar plane waves by resistive surfaces are investigated by defining a new boundary condition in terms of the Dirichlet and Neumann conditions. The scattering problems of waves by a resistive half-plane and the interface between resistive and perfectly magnetic conducting half-planes are examined with the developed method. The resulting fields are plotted numerically. The numerical results show that the evaluated field expressions are in harmony with the theory.
Dijital Mantık Devrelerinin Tasarımı
(Seçkin Yayıncılık, 2018) Gazi, Orhan; Elektronik ve Haberleşme Mühendisliği
Fast Calculation of Polar Code Bits and Frozen-Bit Locations
(2021) Genç, Fatih; Gazi, Orhan; Elektronik ve Haberleşme Mühendisliği
In this paper, we show that encoding operation for the polar codes can be achieved without the employment of the generator matrix, and all the polar code bits can be generated at the same time using a number of tree-encoding structures running in parallel. Since encoding matrix is not used in the implementation of the polar encoders in digital electronic devices, hardware space is saved, and low complexity hardware applications are achieved. Besides, we also proposed a method for the calculation of split channel parameters, such as Bhattacharyya bounds or average-bit-error probabilities of the transmitted bits using a tree-based structure. Moreover, the proposed structure enables to calculate the probability of bit-error values of all the transmitted bits at the same time in a parallel manner and decide the locations of data and frozen bits very rapidly.
Hierarchical decision making and decision fusion
(IEEE, 2007) Beldek, Ulaş; Leblebicioğlu, Kemal; 59950; Mekatronik Mühendisliği
In this study, a hierarchical decision making structure possessing a decision fusion technique is proposed in order to solve decision making problems efficiently. The proposed structure mainly depends on effects of the decisions made in the lower levels to decisions in the upper levels up to an activation degree. The proposed hierarchical structure is used for detecting the fault degrees for single and multiple fault scenarios artifically generated in a four tank system. The results obtained demonstrate the effectiveness of the proposed hierarchical decision making structure.
High Performance Low Latency Parallel Successive Cancelation Decoder Structures for Polar Codes
(2020) Alrataim, Abdelkareim; Gazi, Orhan; Elektronik ve Haberleşme Mühendisliği
Polar codes are decoded using successive cancellation (SC) algorithm where likelihood ratios (LRs) for data bits are calculated in a sequential manner, and decisions are made using the calculated LRs. During the decoding of an information bit, the decision results for the predecessor bits are used, and a wrongly decided predecessor bit has negative effect on the accurate calculation of the LR for the information bit being decoded. In SC algorithm, when LR=1, the information bit is decoded as u ̂_i=0, however, such a decision has 50% of chance of being correct. In this paper, we propose improved polar decoders utilizing a number of SC decoders. We consider the case of LR=1, and propose polar decoder structures for the more accurate calculation of the LRs of the successor bits
Hydrogen hosting of nanoscale boron cluster
(Editura Academiei Romane, 2008) Böyükata, Mustafa; Özdoğan, C.; Güvenç, Ziya B.; 40569; Ortak Dersler Bölümü; Bilgisayar Mühendisliği
In this paper the Density Functional Results of hydrogen bonded boron micro clusters with B3LYP/6-311++G(d,p) level of computations will be presented. Energetics and structural stability with their possible stable geometries of various selected micro complexes of B(m)H(n) (for m and n <= 11 )boron hydrides have been analysed, and their binding energies with HOMO-LUMO energy gaps have been determined. Mainly, erects of the number of hydrogen atoms on the structures of the boranes are assessed. Moreover, for the cage configurations their distortions have been investigated for the neutral, anionic and cationic cases. It has been observed that there have been two opposing factors for the cage configurations. One of which is the "peeling" of the cage structures by the hydrogen atoms, and the other one is reforming a smaller cage form simultaneously with there remaining boron atoms inside. This is observed mostly for the odd values of m. From our studies it has been also observed that with the bare boronclusters alone, it is difficult to increase the capacity of the hydrogen storage. Therefore, further studies are necessary with the boron complexes
Information theory perspective of polar codes and polar encoding
(2019) Gazi, Orhan; 102896; Elektronik ve Haberleşme Mühendisliği
Polar codes are one of the recently discovered capacity achieving channel codes. What makes the polar codes different from other channel codes is that polar codes are designed mathematically and their performance are mathematically proven. © Springer Nature Singapore Pte Ltd. 2019.
Karar Yayılım Algoritması ile Kutup Kodlarının Çözümlenmesi
(2018) Arlı, A. Çağrı; Gazi, Orhan; 102896; Elektronik ve Haberleşme Mühendisliği
MATLAB simulation of multiuser detection in CDMA
(World Acad Sci, 2005) Eyyuboğlu, Halil T.; 7688; Elektronik ve Haberleşme Mühendisliği
This paper describes the MATLAB simulation of multiuser detection in code division multiple access (CDMA). To reach low bit error rate (BER) levels within reasonable computation times, the method of importance sampling is utilized. Our design is based on the step by step practical implementation of matched filter (MF) detection, has therefore the flexibility of variations in all parameters of interest which are otherwise difficult to accommodate in a theoretical model. Our initial findings are compared and verified against theoretical predictions and against those available in the literature.
Modified theory of physical optics
(2004) Umul, Yusuf Ziya; 42699; Elektronik ve Haberleşme Mühendisliği
A new procedure for calculating the scattered fields from a perfectly conducting body is introduced. The method is defined by considering three assumptions. The reflection angle is taken as a function of integral variables, a new unit vector, dividing the angle between incident and reflected rays into two equal parts is evaluated and the perfectly conducting (PEC) surface is considered with the aperture part, together. This integral is named as Modified Theory of Physical Optics (MTPO) integral. The method is applied to the reflection and edge diffraction from a perfectly conducting half plane problem. The reflected, reflected diffracted, incident and incident diffracted fields are evaluated by stationary phase method and edge point technique, asymptotically. MTPO integral is compared with the exact solution and PO integral for the problem of scattering from a perfectly conducting half plane, numerically. It is observed that MTPO integral gives the total field that agrees with the exact solution and the result is more reliable than that of classical PO integral. (C) 2004 Optical Society of America.
On parallelized serially concatenated codes
(IEEE, 2007) Gazi, Orhan; Yılmaz, A. Özgüer; 102896; Elektronik ve Haberleşme Mühendisliği
Serial concatenated codes show very good performance at low signal to noise ratios. However, large decoding delays due to long input frame lengths constitute a major disadvantage for these type of codes. In this study we introduce a new class of concatenated convolutional codes which are very suitable for parallel decoding, thus have much less decoding delays and also show comparable performance to that of classical serial concatenated convolutional codes. The analytical upper bound expressions for performance of the proposed structures are derived using the uniform interleaver concept.
Propagation of optical flat-topped gaussian beams in satellite links
(IEEE, 2009) Kamacıoğlu, Canan; Altay Arpalı, Serap; Baykal, Yahya; Yazgan, Erdem; 51304; 7812; Elektrik-Elektronik Mühendisliği; Elektronik ve Haberleşme Mühendisliği
Propagation of optical flat-topped Gaussian beams in earth-satellite optical communication links is investigated where part of the link is turbulent atmosphere. Flat-topped Gaussian source field is obtained by superposing many Gaussian beams of different source size. Starting with the flat-topped Gaussian incidence at the earth surface, the average intensity at the satellite is formulated by using the extended Huygens Fresnel principle. For the structure constant variation versus height, Hufnagel-Valley model is employed in the vertical and slant paths. The received average intensity is numerically calculated and the effects of the source and medium parameters on the received average intensity profile are examined for different zenith angles. In earth-satellite optical communications links, the advantages of using flat-topped Gaussian beams as compared to Gaussian beams are scrutinized.

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Browsing Elektronik ve Haberleşme Mühendisliği Bölümü by Department "Çankaya Üniversitesi, Mühendislik Fakültesi, Elektronik ve Haberleşme Mühendisliği Bölümü"