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1
Content available Improving Performance of MC-CDMA Systems Using UTTCM Channel Coding
Bendjillali Ridha Ilyas, Bendelhoum Mohammed Sofiane, Abderraouf Elarbi, Lahcene Mohamed
Journal of Telecommunications and Information Technology
|
2024
|
nr 2
58--65
EN
Over the past decade, personal communications have witnessed exponential growth, fueled by the increasing number of connected users and the diversity of transmitted data types. This expansion necessitates a boost in the transmission systems' capacity to accommodate higher user numbers and data rates, simultaneously striving to optimize cost and complexity. Consequently, future communication systems are pivoting towards multi-carrier spread spectrum techniques (MC-CDMA), capitalizing on the robustness of OFDM multi-carrier transmissions against multipath propagation and leveraging the flexibility of the code division multiple access (CDMA) technique. \\This study addresses data transmission quality-related concerns within an MC-CDMA system by implementing UTTCM error correction codes. These codes aim to enhance channel spectrum efficiency and mitigate error probability. Simulation results demonstrate that the proposed transmission scheme offers significant improvements in terms of bit error rate and signal-to-noise ratio, while maximizing the bandwidth shared among users. Additionally, the incorporation of such equalization techniques as zero forcing (ZF) and minimum mean square error (MMSE), ensures extensive compensation for the channel selectivity effect
2
Content available remote An efficient approach for optimization of the parameters In transmission system applied In DWT+SPIHT using whale algorithm (WA)
Mourad Larbi, Mustapha Khelifi, Mohamed Rida Lahcene
Przegląd Elektrotechniczny
|
2022
|
R. 98, nr 11
71--78
EN
The compression of image using analyzing techniques give us q high quality in the reconstructed image however in the case of transmission produce a sensitive (to the channel noise) image .In this paper we are going to use combination between error detection , source and channel coding with unequal distribution in the code rate our approach shows a high efficiency and optimization in the use of the code rate using Whale Algorithm (WA) (minimization in the redundant bits) compared to other approaches. The results of the work carried out in this article are mainly focused on the medical images compression by the (DWT+SPIHT) method, which, in fact, allow a significant reduction for data. We are also interested in the transmission of these images on an channel in a way that can provide a high bit rate with good transmission quality, by exploiting the channel coding technique, which is effective in combating the noise introduced during the transmission of these images.
PL
Kompresja obrazu przy użyciu technik analitycznych daje nam q wysoką jakość rekonstruowanego obrazu, jednak w przypadku transmisji wytwarzamy obraz wrażliwy (na szum kanału). przy nierównym rozkładzie współczynnika kodowania nasze podejście wykazuje wysoką wydajność i optymalizację w wykorzystaniu współczynnika kodowania przy użyciu algorytmu wieloryba (WA) (minimalizacja w nadmiarowych bitach) w porównaniu z innymi podejściami. Wyniki prac przeprowadzonych w niniejszym artykule koncentrują się głównie na kompresji obrazów medycznych metodą (DWT+SPIHT), która w rzeczywistości pozwala na znaczną redukcję danych. Interesuje nas również transmisja tych obrazów na kanale w sposób, który może zapewnić wysoką przepływność przy dobrej jakości transmisji, wykorzystując technikę kodowania kanałów, która skutecznie zwalcza szumy wprowadzane podczas transmisji tych obrazów.
3
Content available High-Rate Permutation Coding with Unequal Error Protection
Ogunyanda Kehinde, Swart Theo G., Ogunyanda Opeyemi O.
International Journal of Electronics and Telecommunications
|
2022
|
Vol. 68, No. 1
27--33
EN
Channel coding provides numerous advantages to digital communications. One of such advantages is error correcting capabilities. This, however, comes at the expense of coding rate, which is a function of the codebook’s cardinality |C| or number of coded information bits and the codeword length M. In order to achieve high coding rate, we hereby report a channel coding approach that is capable of error correction under power line communications (PLC) channel conditions, with permutation coding as the coding scheme of choice. The approach adopts the technique of unequal error correction for binary codes, but with the exception that non-binary permutation codes are employed here. As such, certain parts of the information bits are coded with permutation symbols, while transmitting other parts uncoded. Comparisons with other conventional permutation codes are presented, with the proposed scheme exhibiting a relatively competitive performance in terms of symbol error rate.
4
Content available The design of structured LDPC codes with algorithmic graph construction
Sułek Wojciech
Bulletin of the Polish Academy of Sciences. Technical Sciences
|
2022
|
Vol. 70, nr 4
art. no. e141592
EN
Low-Density Parity-Check (LDPC) codes are among the most effective modern error-correcting codes due to their excellent correction performance and highly parallel decoding scheme. Moreover, the nonbinary extension of such codes further increases performance in the short-block regime. In this paper, we review the key elements for the construction of implementation-oriented binary and nonbinary codes. These Quasi-Cyclic LDPC (QC-LDPC) codes additionally feature efficient encoder and decoder implementation frameworks. We then present a versatile algorithm for the construction of both binary and nonbinary QC-LDPC codes that have low encoding complexity and an optimized corresponding graph structure. Our algorithm uses a progressive edge growth algorithm, modified for QC-LDPC graph construction, and then performs an iterative global search for optimized cyclic shift values within the QC-LDPC circulants. Strong error correction performance is achieved by minimizing the number of short cycles, and cycles with low external connectivity, within the code graph. We validate this approach via error rate simulations of a transmission system model featuring an LDPC coder-decoder, digital modulation, and additive white Gaussian noise channels. The obtained numerical results validate the effectiveness of the proposed construction algorithm, with a number of constructed codes exhibiting either similar or superior performance to industry standard binary codes and selected nonbinary codes from the literature.
5
Efektywność widmowa PA-BICM-ID w kanale z selektywnymi zanikami Rayleigha
Krasicki M.
Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne
|
2018
|
nr 6
363--366, CD
PL
W artykule przedstawiono nowe wyniki badań jakości transmisji w kanale z zanikami selektywnymi Rayleigha przy użyciu modulacji PA-BICM-ID (Packet- Appended Bit-Interleaved Coded Modulation with Iterative Decoding) i zwielokrotnienia OFDM. Po raz pierwszy dla takiego kanału porównano wyniki efektywności widmowej systemów wykorzystujących, odpowiednio, PA-BICM-ID i BICM-ID. Stworzony model symulacyjny miał odzwierciedlać właściwości sieci WLAN, tak w zakresie modelu kanału, jak i struktury symbolu OFDM.
EN
The paper is to contribute some new results displaying the performance of OFDM-Aided Packet- Appended Bit-Interleaved Coded Modulation with Iterative Decoding over frequency-selective Rayleigh fading channel. It is the first time PA-BICM-ID is compared with BICM-ID in terms of spectral efficiency. The simulation setup instantiates a real-world WLAN network with its specific channel model, and OFDM symbol structure.
6
Content available remote The implementation of channel coding into the digital transmission chain consisting of VSG PXI-5670 - VSA PXI-5661
Martinek R., Zidek J.
Przegląd Elektrotechniczny
|
2013
|
R. 89, nr 7
64--68
EN
This article is focused on techniques for error detection and correction, which occur during a transmission in modern digital communication channels. The real implementation of these channel coding techniques into the digital communication system is presented in this article. The system is based on the PXI modular platform consisting of RF VSG PXI-5670 and RF VSA NI PXI-5661. The proposed communication system structure is based on a software-defined radio conception. Author’s goal was to describe and afterwards with real measuring, to revise properties of the measuring system based on this flexible approach. These systems seem to be very useful for testing of new generation transmission systems.
PL
W artykule przedstawiono metody wykrywania i korekcji błędów przy transmisji danych. Zastosowano kodowanie kanałów wykorzystujące systemy RF VSG PXI-5670 i RF VSA NI PXI-5661.
7
Content available Pipeline processing in low-density parity-check codes hardware decoder
Sułek W.
Bulletin of the Polish Academy of Sciences. Technical Sciences
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2011
|
Vol. 59, nr 2
149-155
EN
Low-Density Parity-Check (LDPC) codes are one of the best known error correcting coding methods. This article concerns the hardware iterative decoder for a subclass of LDPC codes that are implementation oriented, known also as Architecture Aware LDPC. The decoder has been implemented in a form of synthesizable VHDL description. To achieve high clock frequency of the decoder hardware implementation – and in consequence high data-throughput, a large number of pipeline registers has been used in the processing chain. However, the registers increase the processing path delay, since the number of clock cycles required for data propagating is increased. Thus in general the idle cycles must be introduced between decoding subiterations. In this paper we study the conditions for necessity of idle cycles and provide a method for calculation the exact number of required idle cycles on the basis of parity check matrix of the code. Then we propose a parity check matrix optimization method to minimize the total number of required idle cycles and hence, maximize the decoder throughput. The proposed matrix optimization by sorting rows and columns does not change the code properties. Results, presented in the paper, show that the decoder throughput can be significantly increased with the proposed optimization method.
8
Content available Joint Source-Channel Coding in Dictionary Methods of Lossless Data Compression
Rodziewicz M.
International Journal of Electronics and Telecommunications
|
2010
|
Vol. 56, No. 4
351-355
EN
Limitations on memory and resources of communications systems require powerful data compression methods. Decompression of compressed data stream is very sensitive to errors which arise during transmission over noisy channels, therefore error correction coding is also required. One of the solutions to this problem is the application of joint source and channel coding. This paper contains a description of methods of joint source-channel coding based on the popular data compression algorithms LZ'77 and LZSS. These methods are capable of introducing some error resiliency into compressed stream of data without degradation of the compression ratio. We analyze joint source and channel coding algorithms based on these compression methods and present their novel extensions. We also present some simulation results showing usefulness and achievable quality of the analyzed algorithms.
9
Content available Konfigurowalny dekoder kodów LDPC implementowany w układzie FPGA
Sułek W.
Pomiary Automatyka Kontrola
|
2009
|
R. 55, nr 8
606-608
PL
Kody LDPC są jednymi z najlepszych znanych klas kodów nadmiarowych, służących do korekcji błędów w kanale telekomunikacyjnym. W niniejszej pracy zaprezentowano opisany w języku VHDL konfigurowalny dekoder podklasy kodów LDPC zorientowanych na efektywną sprzętową implementację. Możliwe jest dostosowanie dekodera dla dowolnego kodu LDPC ze zdefiniowanej podklasy, jak również konfiguracja pewnych parametrów dekodera decydujących o jego własnościach strukturalnych oraz własnościach korekcyjnych systemu. W artykule przedstawiono możliwości konfiguracji dekodera oraz wyniki implementacji: zasoby strukturalne oraz przepustowość dla kilku wybranych kodów.
EN
The group of Low-Density Parity-Check (LDPC) codes is one of the best known error correcting coding methods that are capable of achieving very low bit error rates at code rates approaching Shannon's channel capacity limit. The article concerns the configurable decoder for a subclass of LDPC codes that are implementation oriented. The decoder has a form of synthesizable VHDL description. It can be adjusted for decoding any code from defined subclass, called Architecture Aware LDPC (AA-LDPC). Configuration of some decoder parameters (message calculating algorithm, message wordlength) is possible as well. These parameters affect decoder structural properties and on the other hand - error correcting performance of the coding system. A number of modifications in the VHDL source code are required to adjust the decoder to the particular AA-LDPC code. These modifications can be made automatically by a software that has been created using Matlab tool. The user needs only to specify the parity check matrix that has architecture-aware structure as well as to specify other parameters of the decoder, such as: message wordlength, maximum number of iteration, the number of computing units (SISO) and the SISO message update (sub-optimal) algorithm. Based on these parameters, automatic generation of synthesizable VHDL description can be performed by the software tool that has been created. The decoder is implemented with the Xilinx VirtexII FPGA device. The simulation environment, making use of the hardware decoder is a base of the platform for fast simulation of the developed LDPC coding systems performance. In this paper we present mainly the decoder reconfiguration methods. Implementation results: structural resources and decoder throughput for a couple of different codes are presented as well.
10
Content available remote DAVINCI Codes as Example of High Performance Non-Binary LDPC
Kiedrowski Ł., Gierszal H., Hołubowicz W., Flizikowski A.
Electronics and Telecommunications Quarterly
|
2009
|
Vol. 55, No 3
417-433
EN
The article presents a new family of non-binary LDPC which has been elaborated within a framework of DAVINCI project. They are based on a finite field GF(64). We compare their error rate to other channel coding techniques. Results prove that DAVINCI codes allow improving the coding performance.
11
Radiofonia cyfrowa w zakresach fal długich, średnich i krótkich
Walewski K.
Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne
|
2004
|
nr 11
437-442
PL
Przedstawiono nowy system radiofonii cyfrowej opracowany przez międzynarodowe konsorcjum pod nazwą Digital Radio Mondiale (DRM), który został oficjalnie zaprezentowany w r. 2003. System jest przystosowany do naziemnej emisji sygnałów w zakresie częstotliwości poniżej 30 MHz i uzyskał standaryzację w ramach ETSI. Można się spodziewać, że w niedługim czasie zastąpi analogową radiofonię z modulacją amplitudową. Omówiono założenia systemu i jego charakterystyki oraz przyjęte rozwiązania dotyczące sposobu modulacji i zabezpieczania sygnałów przed błędami oraz zniekształceniami wprowadzanymi przez kanał. Wskazano możliwości dostosowania systemu DRM do lokalnych warunków pracy, tj. emisję sygnałów w pasmach o różnej szerokości, wspólną transmisję sygnału analogowego i cyfrowego oraz różne sposoby zabezpieczania sygnałów przed błędami wprowadzanymi przez kanał, Przedstawiono charakterystyki koderów źródłowych, które są wykorzystywane w systemie DRM.
EN
In the paper a new digital audio broadcasting system is presented that has been developed by a consortium Digital Radio Mondiale (DRM) to replace AM broadcasting system by digital technology. The application of DRM system is anticipated in terrestrial broadcasting bands below 30 MHz. This paper describes the features and characteristics of DRM system in which the transmission of digital signals in wider or narrower channels provides flexibility in adopting radio broadcasting to local requirements. Besides, different source coding modes as well as multilevel channel coding schemes and multilevel modulation allow for a trade off between available capacity of the channel and immunity to noise, multipath propagation and Doppler shift.
12
Content available A solution for increasing data rate of Doppler-RAKE system
Nguyen Nguyen M., Modelski J.
Journal of Telecommunications and Information Technology
|
2003
|
nr 3
130-134
EN
Doppler-RAKE detection in the CDMA system has been further developed and offers better performances in comparison to conventional RAKE detection, especially in fast-fading environments. Also, the multi-user Doppler-RAKE system works more effectively with channel coding applications. However, by means of exploring the Doppler effect, the system's data rate is decreased. We propose a simple solution to increase the data rate for the system while keeping the Doppler gain.
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