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 Fbmc System With Low Density Parity Check (Ldpc) Coding For Efficient Communications In 5g

2019 ◽  
Vol 8 (6S) ◽  
pp. 961-964
Keyword(s):  
Turbo Codes ◽  
Channel Coding ◽  
Orthogonal Frequency Division Multiplexing ◽  
Cellular Communications ◽  
Wave Form ◽  
Low Density ◽  
Parity Check ◽  
Low Density Parity Check ◽  
5G Communication ◽  
Ber Performance

Channel coding is a complicated subject, but vital in cellular communications, which is used for detection and correction of the bit errors caused by various types of noises, interferences. In 3rd generation and 4th Generation (3G and 4G) cellular communications, Turbo codes are predominantly used and currently 3GPP standardization group considering the Low Density Parity Check (LDPC) code in 5G, due to its requirements of 20GB throughput, ultra low latencies and massive Internet of Things. In 5G Communication Filter Bank Multi Carrier (FBMC) wave form is considered for 5G and beyond communication for non-orthogonal communications due to its superior side-lobe suppression characteristics and also no need to use the cyclic prefix, which will save the bandwidth. With FBMC based systems, the Bit Error Rate (BER) performance is still not able to reach the LTE level, which uses Orthogonal Frequency Division Multiplexing (OFDM). In this paper, to achieve a better BER performance, it is proposed to use the LDPC coding with FBMC waveform for 5G communication and was simulated with Keysight SystemVue Software. The BER analysis is performed for both coded and uncoded data transmission for FBMC system with three different modulations: QPSK, 16QAM, 64QAM. The simulated results shows that the LDPC coding with 1/2 code rate is better than other code rates 2/3, 3/4 and 5/6.

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.

Generalized Trapezoidal Companding Technique for PAPR Reduction in OFDM Systems

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Saruti Gupta ◽  
Ashish Goel
Keyword(s):  
Bit Error Rate ◽  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Frequency Division ◽  
Performance Parameters ◽  
Ofdm Systems ◽  
Ofdm System ◽  
Ofdm Signal ◽  
Specific Degree ◽  
Ofdm Signals

Abstract The main drawback in the performance of the Orthogonal Frequency Division Multiplexing (OFDM) system is the higher Peak-to-Average Power Ratio (PAPR) of the OFDM signals at the transmitter side. Companding is a well-known technique useful for reducing PAPR in the OFDM signal. This paper proposes a new nonlinear companding scheme that transforms the magnitude of Rayleigh distributed OFDM signal of specific degree into trapezoidal distribution. Additional design parameter is used in the proposed companding scheme to make the companding function more flexible. In the designed OFDM system the companding function has more degree of freedom which improves the PAPR and bit error rate (BER) parameters of the designed system. It has been demonstrated that the designed companding scheme provides more flexibility to accomplish an optimum trade-off between the performance parameters PAPR and BER of the designed OFDM system.

scholarly journals Performance on ICI Self-Cancellation in FFT-OFDM and DCT-OFDM System

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Shilpi Gupta ◽  
Upena Dalal ◽  
Vishnu Narayan Mishra
Keyword(s):  
Bit Error Rate ◽  
Orthogonal Frequency Division Multiplexing ◽  
The Other ◽  
Frequency Division Multiplexing ◽  
Intercarrier Interference ◽  
Frequency Division ◽  
Ofdm System ◽  
Awgn Channel ◽  
Energy Compaction ◽  
Carrier To Interference Ratio

In orthogonal frequency division multiplexing (OFDM) system, the existence of frequency offset in AWGN channel affects the orthogonality among the subcarriers and consequently introduces the intercarrier interference (ICI). The paper investigates new ICI self-cancellation technique to mitigate the effect of ICI in FFT-OFDM and compares it to DCT based OFDM system in terms of bit error rate (BER) and carrier to interference ratio (CIR). The proposed method for group size three results in a significant 20 dB improved CIR in FFT-OFDM. In terms of BER, proposed ICI self-cancellation technique outperforms the other self-cancellation techniques in FFT-OFDM. Also, this paper investigates outperforming BER and CIR improvement by using DCT-OFDM without applying self-cancellation techniques, due to its energy compaction property.

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