WoS İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8653

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Citation - WoS: 0
Citation - Scopus: 1
Analysis of parallel decodable turbo codes
(Ieice-inst Electronics information Communications Eng, 2012) Gazi, Orhan; 102896; Elektronik ve Haberleşme Mühendisliği
Turbo codes suffer from high decoding latency which hinders their utilization in many communication systems. Parallel decodable turbo codes (PDTCs) are suitable for parallel decoding and hence have low latency. In this article, we analyze the worst case minimum distance of parallel decodable turbo codes with both S-random interleaver and memory collision free Row-Column S-random interleaver. The effect of minimum distance on code performance is determined through computer simulations.
Citation - WoS: 6
Citation - Scopus: 6
Applications of Cognitive Radio Networks: Recent Advances and Future Directions
(Sage Publications inc, 2016) Kim, Sung W.; Pan, Miao; Joshi, Gyanendra Prasad; Gazi, Orhan; He, Jianhua; Coupechoux, Marceau; 102896; Elektronik ve Haberleşme Mühendisliği
Citation - WoS: 4
Citation - Scopus: 4
Bounds for generalized gamma distributed fading channels
(Ieee-inst Electrical Electronics Engineers inc, 2011) Gazi, Orhan; 102896; Elektronik ve Haberleşme Mühendisliği
In 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.
Citation - WoS: 7
Citation - Scopus: 8
Collision free row column s-random interleaver
(Ieee-inst Electrical Electronics Engineers inc, 2009) Gazi, Orhan; Yilmaz, A. Oezguer; 102896; Elektronik ve Haberleşme Mühendisliği
Parallel 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.
Citation - WoS: 3
Citation - Scopus: 6
Decoding of LT-like codes in the absence of degree-one code symbols
(Electronics Telecommunications Research inst, 2016) Abdulkhaleq, Nadhir I.; Gazi, Orhan; 102896; Elektronik ve Haberleşme Mühendisliği
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.
Citation - WoS: 5
Fast decodable turbo codes
(Ieee-inst Electrical Electronics Engineers inc, 2007) Gazi, Orhan; Yilmaz, A. Ozgar; 102896; 111575; Elektronik ve Haberleşme Mühendisliği
Decoding delay is an important consideration for the use of turbo codes in practical applications. We propose a new structure for turbo codes which is very suitable for parallel decoding. It is shown by union bound analysis and simulation results that the proposed system performance is comparable to that of the classical turbo codes.
Citation - WoS: 5
Citation - Scopus: 8
Fast decoding of polar codes using tree structure
(inst Engineering Technology-iet, 2019) Andi, Alia A.; Gazi, Orhan; 102896; Elektronik ve Haberleşme Mühendisliği
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.
Citation - WoS: 0
Citation - Scopus: 0
Low latency hybrid structures ınvolving convolutional product like codes and space time codes
(Springer, 2017) Gazi, Orhan; Al-Kattan, Ahmed A. S.; 102896; Elektronik ve Haberleşme Mühendisliği
In 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.
Citation - WoS: 0
Citation - Scopus: 2
Mathematical modeling of stochastic resonance systems
(Ieee, 2018) Arli, A. Cagri; Gazi, Orhan; 102896; Elektronik ve Haberleşme Mühendisliği
Knowledge of at which condition in a nonlinear threshold system stochastic resonance phenomena occurs, can be important in noise introduced threshold systems. A new method for mathematical modeling of stochastic resonance systems is introduced. The proposed approach can be used for the modeling of many other phenomenons. It's shown that using the mathematical model developed for stochastic resonance systems it's possible to estimate the optimum noise variances necessary for the occurrence of the stochastic resonance. The accuracy of the estimated noise variances are verified by the simulation results.
Citation - WoS: 2
Citation - Scopus: 3
New Early Termination Methos For Turbo Decoders
(Ieee, 2014) Gazi, Orhan; Gazi, Orhan; 102896; Elektronik ve Haberleşme Mühendisliği
Turbo 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.
Citation - WoS: 27
Noise-Aided Belief Propagation List Decoding of Polar Codes
(Ieee-inst Electrical Electronics Engineers inc, 2019) Arli, A. Cagri; Gazi, Orhan; 102896; 206005; Elektronik ve Haberleşme Mühendisliği
Noise can help weak information bearing signal to be detected in nonlinear systems by the use of stochastic perturbation. In this letter, we propose a novel belief propagation list (BPL) decoder that relies on artificial noise. The proposed decoder is constructed by using parallel independent BP decoders. Noise with different powers are added to different BP decoders that runs in parallel, and the output of the decoder that pass the early detection and termination criteria check is considered as the recovered data. Adding small amount of noise enables the decoder to handle un-converged errors. The obtained results show that the performance of noise-aided BPL decoder is much better than the performances of BP, successive cancelation (SC), and successive cancelation list (SCL) decoders, and it is a bit behind of cyclic redundancy check aided SCL in terms of bit-error rate performance.
Citation - WoS: 1
Citation - Scopus: 2
Prunable collision free random interleaver design
(Springer, 2012) Gazi, Orhan; 102896; Elektronik ve Haberleşme Mühendisliği
In 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.
Citation - WoS: 1
Citation - Scopus: 1
The Effect of Error Propagation on the Performance of Polar Codes Utilizing Successive Cancellation Decoding Algorithm
(Advanced Electromagnetics, Geeps-supelec, 2019) Andi, Alia A.; Gazi, Orhan; 102896; Elektronik ve Haberleşme Mühendisliği
In this paper, we discuss and analyze the effect of error propagation on the performance polar codes decoded using the successive cancellation algorithm. We show that error propagation due to erroneous bit decision is a catastrophic issue for the successive cancellation decoding of polar codes. Even a wrong decision on a single bit may cause an abundance of successor bits to be wrongly decoded. Furthermore, we observe that the performance of polar codes is significantly improved if even single bit errors are detected and corrected before the decoding of successor bits.
Citation - WoS: 0
Citation - Scopus: 0
The implementation of a successive cancellation polar decoder on xilinx system generator
(Ieee, 2017) Arli, A. Cagri; Colak, Ayse; Gazi, Orhan; 206005; 102896; Elektronik ve Haberleşme Mühendisliği
Polar 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.
Citation - WoS: 10
Citation - Scopus: 29
The role of delay and connectivity in throughput reduction of cooperative decentralized wireless networks
(Hindawi Ltd, 2015) Alkhayyat, Ahmed; Gazi, Orhan; Sadkhan, Sattar B.; 102896; Elektronik ve Haberleşme Mühendisliği
We 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.
Citation - WoS: 17
Citation - Scopus: 22
Turbo product codes based on convolutional codes
(Wiley, 2006) Gazi, Orhan; Yilmaz, Ali Ozgur; 102896; 111575; Elektronik ve Haberleşme Mühendisliği
In 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.
Citation - WoS: 0
Citation - Scopus: 0
Zero state doped turbo equalizer
(Ieee-inst Electrical Electronics Engineers inc, 2007) Gazi, Orhan; Yilmaz, A. Ozgur; 102896; 111575; Elektronik ve Haberleşme Mühendisliği
Although iterative equalizers perform well at low signal to noise ratios, high latency is a major disadvantage for their use in practical communication systems. In this article we propose zero state doped turbo equalizers (ZSDTEs) which can be processed in parallel and have significantly reduced processing delays. The proposed technique shows better performance when compared to the sliding window method.

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