Elektronik ve Haberleşme Mühendisliği Bölümü Yayın Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/260
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Article Prunable collision free random interleaver design(Springer, 2012) Gazi, OrhanIn 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.Publication On parallelized serially concatenated codes(IEEE, 2007) Gazi, Orhan; Yılmaz, A. ÖzgüerSerial 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.Article Citation - WoS: 5Citation - Scopus: 9Fast Decoding of Polar Codes Using Tree Structure(inst Engineering Technology-iet, 2019) Gazi, Orhan; Andi, Alia A.In this study, the authors first propose a tree structure for the successive cancelation (SC) decoding of polar codes. The proposed structure is easy to implement in hardware and suitable for parallel processing operations. Next, using the proposed tree structure, they propose a technique for the fast decoding of polar codes. With the proposed method, it is possible to decode all the information bits simultaneously at the same time, i.e. in parallel. Lastly, they introduce an improved version of the proposed high-speed decoding algorithm. The proposed high-speed decoding approach and its improved version are simulated on the computer environment and their bit error rate performances are compared to the performance of the classical SC method.Article Low Latency Hybrid Structures Involving Convolutional Product Like Codes and Space Time Codes(Springer, 2017) Al-Kattan, Ahmed A. S.; Gazi, OrhanIn this paper, we propose new joint serially concatenated communication structures constructed from convolutional product codes and space time codes. The proposed structures are suitable for parallel processing operations and they have very low decoding latencies compared to their classical counterparts. Use of multi-antennas increases the spectral efficiency of the joint structures.Article Citation - WoS: 3Citation - Scopus: 6Decoding of Lt-Like Codes in the Absence of Degree-One Code Symbols(Electronics Telecommunications Research inst, 2016) Gazi, Orhan; Abdulkhaleq, Nadhir I.Luby transform (LT) codes were the first practical rateless erasure codes proposed in the literature. The performances of these codes, which are iteratively decoded using belief propagation algorithms, depend on the degree distribution used to generate the coded symbols. The existence of degree-one coded symbols is essential for the starting and continuation of the decoding process. The absence of a degree-one coded symbol at any instant of an iterative decoding operation results in decoding failure. To alleviate this problem, we proposed a method used in the absence of a degree-one code symbol to overcome a stuck decoding operation and its continuation. The simulation results show that the proposed approach provides a better performance than a conventional LT code and memory-based robust soliton distributed LT code, as well as that of a Gaussian elimination assisted LT code, particularly for short data lengths.Article Citation - WoS: 10Citation - Scopus: 30The Role of Delay and Connectivity in Throughput Reduction of Cooperative Decentralized Wireless Networks(Hindawi Ltd, 2015) Gazi, Orhan; Sadkhan, Sattar B.; Alkhayyat, AhmedWe proposed a multiple relay selection protocol for decentralized wireless networks. The proposed relays selection protocol aims to address three issues: (1) selecting relays within the coverage area of the source and destination to ensure that the relays are positioned one hop away from the destination, (2) ensuring that the best node (best relays with less distance and attenuation from the destination) access the channel first, and (3) ensuring that the proposed relays selection is collision-free. Our analysis also considers three important characteristics of decentralized wireless networks that are directly affected by cooperation: delay, connectivity, and throughput. The main goal of this paper is to demonstrate that improving connectivity and increasing number of relays reduce the throughput of cooperative decentralized wireless networks; consequently, a trade-off equation has been derived.Article Citation - WoS: 1Citation - Scopus: 2Prunable Collision Free Random Interleaver Design(Springer, 2012) Gazi, OrhanIn 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 Citation - WoS: 17Citation - Scopus: 22Turbo Product Codes Based on Convolutional Codes(Wiley, 2006) Yilmaz, Ali Ozgur; Gazi, OrhanIn 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.