Low-density parity check coded orthogonal frequency division multiplexing for PLC in non-Gaussian noise using LLRs derived from effective noise probability density functions

2017 ◽  
Vol 11 (16) ◽  
pp. 2425-2432 ◽  
Author(s):  
Ghanim A. Al-Rubaye ◽  
Charalampos C. Tsimenidis ◽  
Martin Johnston
Keyword(s):  
Gaussian Noise ◽  
Orthogonal Frequency Division Multiplexing ◽  
Probability Density Functions ◽  
Density Functions ◽  
Frequency Division Multiplexing ◽  
Low Density ◽  
Frequency Division ◽  
Parity Check ◽  
Low Density Parity Check ◽  
Non Gaussian

scholarly journals Estimador de canal basado en sensado compresivo y LDPC para OFDM usando SDR

Ingenius ◽  
2019 ◽  
pp. 74-85
Author(s):  
Juan Paúl Inga Ortega ◽  
Anthony Yanza Verdugo ◽  
Christian Pucha Cabrera
Keyword(s):  
Software Defined Radio ◽  
Orthogonal Frequency Division Multiplexing ◽  
Matching Pursuit ◽  
Compressive Sampling ◽  
Frequency Division Multiplexing ◽  
Low Density ◽  
Frequency Division ◽  
Parity Check ◽  
Low Density Parity Check ◽  
Restriction Property

Este trabajo propone la aplicación de un estimador de canal basado en sensado compresivo (CS, del inglés Compressive Sensing) sobre un sistema que usa multiplexación por división de frecuencias ortogonales (OFDM, del inglés Orthogonal Frequency Division Multiplexing) usando dispositivos de radio definido por \emph{software} (SDR, del inglés Software Defined Radio). La aplicación de la teoría de CS se da a través del uso de algoritmos de reconstrucción dispersa como Orthogonal Matching Pursuit (OMP) y Compressive Sampling Matching Pursuit (CoSaMP) con el fin de aprovechar la naturaleza dispersa de las subportadoras piloto usadas en OFDM optimizando el ancho de banda del sistema. Además, para mejorar el rendimiento de estos algoritmos, se utiliza el concepto de la matriz de comprobación de paridad dispersa que se implementa en el despliegue de códigos de comprobación de paridad de baja densidad (LDPC, del inglés Low Density Parity Check) para obtener una matriz de sensado que mejore la propiedad de restricción isométrica (RIP, del inglés Isometric Restriction Property) perteneciente al paradigma de CS. El documento muestra el modelo implementado en los equipos SDR analizando la tasa de error de bit y la cantidad de símbolos piloto usados.

scholarly journals BER Performance Analysis of a Concatenated Low Density Parity Check Encoded OFDM System in AWGN and Fading Channels

2009 ◽  
Vol 2 (1) ◽  
pp. 46-53 ◽  
Author(s):  
M. D. Haque ◽  
S. E. Ullah ◽  
M. M. Rahman ◽  
M. Ahmed
Keyword(s):  
Fading Channels ◽  
Bit Error Rate ◽  
Orthogonal Frequency Division Multiplexing ◽  
Color Image ◽  
Low Density ◽  
Frequency Division ◽  
Parity Check ◽  
Ofdm System ◽  
Low Density Parity Check ◽  
Ber Performance

In this paper, we investigate the bit error rate (BER) performance of a concatenated low density parity check (LDPC) encoded orthogonal frequency-division multiplexing (OFDM) system on color image transmission. In FEC concatenated channel coding, the OFDM wireless communication system incorporates 1/2-rated convolution encoder under various digital modulations (QPSK, 8PSK, QAM, 8QAM, 16QAM and 32QAM) over an additative white gaussian noise (AWGN) and other fading (Raleigh and Rician) channels. Computer simulation results on BER demonstrate that the LDPC encoded OFDM system outperforms with QAM modulation technique as compared to other digital modulation scheme and the system is highly effective to combat inherent interferences under Rayleigh and Rician fading channels. The transmitted color image is found to have retrieved effectively under noisy and fading situations with implementation of sum-product algorithm, an effective iterative based LDPC decoding scheme. It has also been anticipated that the performance of the communication system degrades with the increasing of noise power. Keywords: Orthogonal frequency division multiplexing (OFDM); Low density parity check (LDPC); Bit error rate (BER). © 2010 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. DOI: 10.3329/jsr.v2i1.2724               J. Sci. Res. 2 (1), 46-53 (2010) 

scholarly journals A New Reliability Ratio Weighted Bit Flipping Algorithm for Decoding LDPC Codes

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Chakir Aqil ◽  
Ismail Akharraz ◽  
Abdelaziz Ahaitouf
Keyword(s):  
Gaussian Noise ◽  
Additive White Gaussian Noise ◽  
Ldpc Codes ◽  
Low Density ◽  
Parity Check ◽  
Coding Gain ◽  
Decoding Complexity ◽  
Low Density Parity Check ◽  
Awgn Channel ◽  
Infinite Loop

In this study, we propose a “New Reliability Ratio Weighted Bit Flipping” (NRRWBF) algorithm for Low-Density Parity-Check (LDPC) codes. This algorithm improves the “Reliability Ratio Weighted Bit Flipping” (RRWBF) algorithm by modifying the reliability ratio. It surpasses the RRWBF in performance, reaching a 0.6 dB coding gain at a Binary Error Rate (BER) of 10−4 over the Additive White Gaussian Noise (AWGN) channel, and presents a significant reduction in the decoding complexity. Furthermore, we improved NRRWBF using the sum of the syndromes as a criterion to avoid the infinite loop. This will enable the decoder to attain a more efficient and effective decoding performance.

Preliminary Investigation of Gray Coded M–Quadrature Amplitude Modulation in Orthogonal Frequency Division Multiplexing Over Additive White Gaussian Noise Channel

2012 ◽  
Author(s):  
Nor K. Noordin ◽  
Borhanuddin M. Ali ◽  
S. S. Jamuar ◽  
Tharek A. Rahman ◽  
Mahamod B. Ismail
Keyword(s):  
Bit Error Rate ◽  
Amplitude Modulation ◽  
Gaussian Noise ◽  
Orthogonal Frequency Division Multiplexing ◽  
Signal To Noise Ratio ◽  
Quadrature Amplitude Modulation ◽  
Cyclic Prefix ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Signal To Noise

Dalam makalah ini, kami menyelidik prestasi M–Modulasi Amplitud Kuadratur terkod–Gray dalam sistem penghantaran menggunakan skema Multiplexan Pembahagian Frekuensi Ortogonal (OFDM) melalui saluran hingar Gaussian (AWGN). QAM terkod Gray dengan 1 bit ke 8 bit per simbol bersamaan dengan 2–QAM ke 256–QAM dijana dan dimasukkan ke dalam sistem penghantaran OFDM. Prestasi sistem dalam bentuk kadar ralat bit (BER) diberi berbanding saiz jelmaan Fourier pantas (FFT), bilangan sub-pembawa, panjang prefix-kitaran, dan toleransi terhadap nisbah isyarat kepada hingar (SNR) dalam saluran. Dapatan awal menunjukkan hanya modulasi 16–QAM ke bawah boleh diterimapakai untuk mencapai BER sebanyak 10–3 dengan SNR sekurang-kurangnya 20 dB. Peringkat modulasi yang lebih tinggi seperti 256–QAM memerlukan SNR sebanyak 50 dB untuk mencapai hasil BER yang sama. Kajian juga menunjukkan prestasi sistem ini tidak tergugat dengan perubahan saiz FFT mahupun panjang prefix-kitaran yang dimasukkan ke dalam isyarat yang dihantar. Walau bagaimanapun, bilangan sub-pembawa bergantung kepada peringkat QAM yang digunakan untuk suatu nilai SNR yang diberi. Kata kunci: Multiplexan pembahagian frekuensi ortogonal (OFDM), modulasi kuadratur (QAM), pengkodan gray, dan jelmaan fourier pantas In this paper, we investigate the performance of Gray encoding M–Quadrature Amplitude Modulation (QAM) schemes in Orthogonal Frequency Division Multiplexing (OFDM) transmission over added white Gaussian noise (AWGN) channel. Gray–coded QAM with 1 to 8–bit symbol corresponding to 2 to 256–QAM respectively is generated and fed into OFDM transmission system. Performance in terms of bit error rate (BER) is presented against OFDM fast Fourier transform (FFT) size, subcarrier number, length of cyclic prefix, and tolerance to signal to noise ratio of the channel. Preliminary results show that only 16 and lower level–QAM are attractive to achieve a bit error rate (BER) of 10–3 with signal to noise ratio of at least 20 dB. The higher level QAM such as 256–QAM scheme will require at least a SNR of 50 db to achieve similar outcome. The study also shows that the performance of the system is not affected by the number of fft–points used, or the length of cyclic prefix inserted to the transmitted signal. However, the number of subcarriers does depend on the level of QAM used at a given SNR value. Keywords: Orthogonal frequency division multiplexing (OFDM), quadrature amplitude modulation (QAM), gray coding, fast fourier transform (FFT)

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