Gazi, Orhan
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Doç. Dr.
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Elektronik ve Haberleşme Mühendisliği
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Scholarly Output
48
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36
Citation Count
131
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0
48 results
Scholarly Output Search Results
Now showing 1 - 10 of 48
Conference Object Citation - WoS: 2Citation - Scopus: 3New Early Termination Methos For Turbo Decoders(Ieee, 2014) Gazi, Orhan; Gazi, Orhan; Gazi, Orhan; 102896; Elektronik ve Haberleşme MühendisliğiTurbo codes have large latency due to iterative decoding steps and complex decoding algorithms To decrease the decoding delay it is essential to terminate the decoding operation as soon as there is sufficient information for data bits. Early termination can be achieved by defining stopping criteria beyond which negligible achievement is observed. In this article, we investigate some efficient stopping criteria based on the variance of extrinsic information and population of the bits below a predetermined threshold. We show that variance based method is better than its previously suggested counterparts, and threshold based method is the least complex one considering the available methods.Conference Object Citation - WoS: 0Citation - Scopus: 0The implementation of a successive cancellation polar decoder on xilinx system generator(Ieee, 2017) Arli, A. Cagri; Gazi, Orhan; Colak, Ayse; Gazi, Orhan; 206005; 102896; Elektronik ve Haberleşme MühendisliğiPolar coding is the first kind of the capacity achieving codes which are defined for binary-input discrete memoryless channels initially. Parallel processing property of the FPGA allows to decode faster with a margin of complexity. Xilinx System Generator as a practical tool to construct decoding designs in shorter time is a fact. In this study, FPGA implementation of decoding polar codes through Xilinx System Generator is shown.Article Citation - WoS: 17Citation - Scopus: 22Turbo product codes based on convolutional codes(Wiley, 2006) Gazi, Orhan; Gazi, Orhan; Yilmaz, Ali Ozgur; 102896; 111575; Elektronik ve Haberleşme MühendisliğiIn this article, we introduce a new class of product codes based on convolutional codes, called convolutional product codes. The structure of product codes enables parallel decoding, which can significantly increase decoder speed in practice. The use of convolutional codes in a product code setting makes it possible to use the vast knowledge base for convolutional codes as well as their flexibility in fast parallel decoders. Just as in turbo codes, interleaving turns out to be critical for the performance of convolutional product codes. The practical decoding advantages over serially-concatenated convolutional codes are emphasized.Article Citation - WoS: 4Citation - Scopus: 4Bounds for generalized gamma distributed fading channels(Ieee-inst Electrical Electronics Engineers inc, 2011) Gazi, Orhan; Gazi, Orhan; 102896; Elektronik ve Haberleşme MühendisliğiIn this article, upper bounds for the outage probability and moment generating functions of the fading channels with alpha - mu distribution are derived. The proposed upper bound for the moment generating function is used in the performance evaluation of M - PSK communication systems. The derived expressions are simple to use and do not require complex software tools to evaluate. We verified the proposed expressions via numerical computations.Article Citation - WoS: 7Citation - Scopus: 8Collision free row column s-random interleaver(Ieee-inst Electrical Electronics Engineers inc, 2009) Gazi, Orhan; Gazi, Orhan; Yilmaz, A. Oezguer; 102896; Elektronik ve Haberleşme MühendisliğiParallel decodable turbo codes (PDTCs) are suitable for concurrent decoding and hence have low latency. Memory collision issue is an important problem met during parallel processing. In this article, we propose a collision free interleaver for parallel processing operations. The performance of PDTCs is analyzed with the proposed random interleaver preventing the memory collision problem. Distance spectra of PDTCs with the proposed interleaves are computed and compared to those with S-random interleaver.Book Part Citation - Scopus: 0Entropy for Continuous Random Variables Discrete Channel Capacity, Continuous Channel Capacity(Springer Science and Business Media Deutschland GmbH, 2018) Gazi, O.; Gazi, Orhan; 102896; Elektronik ve Haberleşme MühendisliğiIn this chapter, we will study the entropy concept for continuous random variables. The capacity of both continuous and discrete channels will be inspected in details. The capacity formula for additive white Gaussian channel is to be derived and the factors that affects the capacity of the additive white Gaussian channel will be elaborated. © 2018, Springer Nature Singapore Pte Ltd.Conference Object New Upper Bounds for the Computation of Complementary Error Function(2012) Gazi, Orhan; Elektronik ve Haberleşme MühendisliğiIn this article we provide tighter upper bounds for complementary error function which is a monotonically decreasing function widely used in communication theory. The provided bounds approach the exact value in the limiting case. The derivation of the bounds are based on the monotonically increasing property of exponential function used in complementary error function.Book Part Citation - Scopus: 0Polarization rate and performance of polar codes(Springer Science and Business Media B.V., 2019) Gazi, O.; Gazi, Orhan; 102896; Elektronik ve Haberleşme MühendisliğiIn this chapter, we will mathematically state the channel polarization theorem and prove it. In addition, the performance of polar codes will be mathematically analyzed. © Springer Nature Singapore Pte Ltd. 2019.Article Prunable collision free random interleaver design(2012) Gazi, Orhan; Elektronik ve Haberleşme MühendisliğiIn this article we introduce a new collision free prunable random interleaver. The suggested interleaver is a joint structure involving rectangular and S-random interleaver. It comprises a general model for all kind of collision free prunable random interleavers. In addition, it can be designed for any number of parallel processors and any length of information sequence vector and can be considered also as a template for collision free prunable interleavers. The proposed interleaver can be used with all kind of turbo-like codes. The performance of the proposed interleaver is measured with parallel decodable serially concatenated convolutional codes (PDSCCCs) and compared to the PDSCCCs' performance with collision full S-random interleaver.Article The Research and Design of Multi Relays in Cooperative Communication System Based on Polar Codes(2021) Gazi, Orhan; Gazi, Orhan; 102896; Elektronik ve Haberleşme MühendisliğiIn this paper, we propose a method to increase the performance of cooperative communication using polar codes. For this purpose, we consider non-line-of sight (NLOS) cooperative communication scheme where destination node does not receive signal from source directly. The relay nodes use decodes and forward approach. We propose a voting scheme for the relay nodes, which share information among them. It is shown by the simulation results that the proposed approach significantly improves the performance of relayed communication.
