scholarly journals Real-Time Mitigation of the Mobility Effect for IEEE 802.15.4g SUN MR-OFDM

2019 ◽  
Vol 9 (16) ◽  
pp. 3289 ◽  
Author(s):  
Huy Nguyen ◽  
Nam Tuan Le ◽  
Nguyen Cong Hoan ◽  
Yeong Min Jang
Keyword(s):  
Low Power ◽  
Real Time ◽  
Doppler Shift ◽  
Orthogonal Frequency Division Multiplexing ◽  
Cyclic Prefix ◽  
Wide Area ◽  
Wide Area Networks ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Ofdm System

In order to develop wireless sensor networks, which are defined by the IEEE 802.15.4 specification, researchers are considering low-power wide-area networks (LPWAN) due to their advantages of being long range, low power, low cost, and highly mobile. The issue of mobility is covered in the IEEE 802.15.4g standard for supporting a smart utility network (SUN), which is mainly controlled by orthogonal frequency-division multiplexing (OFDM) modulation. In a high mobility scenario, inter-carrier interference is a primary factor in reducing the performance of OFDM transmissions due to the destruction of the subcarrier component’s orthogonality. This paper analyzes the mobility effect in multi-rate multi-regional orthogonal frequency-division multiplexing (MR-OFDM) for low-power wide-area networks in general, and the SUN MR-OFDM system in particular. As mentioned in standard 802.15.4 2015, IEEE 802.15.4g MR-OFDM is one of the low-power wide-area (LPWA) technologies in which energy optimization problems are of first priority. We are especially interested in simple technologies that provide high efficiency. Therefore, we propose a highly adaptive method that uses the cyclic prefix to mitigate the mobility effect in real time. At a symbol frames interval of 120 us, the Doppler shift effect from the mobility of the MR-OFDM system adapted smoothly. This is not the best method to mitigate Doppler shift but it is a simple method that suits the LPWA network. The proposed scheme clearly simulated the mobility of the MR-OFDM system, and had the advantage of using a cyclic-prefix with a bit error rate performance through Additive White Gaussian Noise (AWGN) and the Rician channel of Matlab.

scholarly journals Deep neural network for orthogonal frequency division multiplexing systems without cyclic prefix transmission

2018 ◽  
Vol 189 ◽  
pp. 04016
Author(s):  
Viet-Hung Nguyen ◽  
Minh-Tuan Nguyen ◽  
Yong-Hwa Kim
Keyword(s):  
Neural Network ◽  
Orthogonal Frequency Division Multiplexing ◽  
Deep Neural Network ◽  
Cyclic Prefix ◽  
Wireless Transmission ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Ofdm System ◽  
New Approach ◽  
Multiplexing Systems

Orthogonal frequency division multiplexing (OFDM) is widely used in wired or wireless transmission systems. In the structure of OFDM, a cycle prefix (CP) has been exploited to avoid the effects of inter-symbol interference (ISI) and inter-carrier interference (ICI). This paper proposes a new approach to transmit the signals without CP transmission. Using the deep neural network, the proposed OFDM system transmits data without the CP. Simulation results show that the proposed scheme can estimate the CP at the receiver and overcome the effect of ISI.

scholarly journals The effect of wavelet transform on OFDM system in modern cellular networks

2019 ◽  
Vol 15 (1) ◽  
pp. 324
Author(s):  
Mayada Faris Ghanim
Keyword(s):  
Fourier Transform ◽  
Wavelet Transform ◽  
Wireless Communications ◽  
Cellular Networks ◽  
Orthogonal Frequency Division Multiplexing ◽  
Cyclic Prefix ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Ofdm System

Wavelet transform has many advantages that make it suitable and efficient approach to replace Fast Fourier Transform (FFT) in conventional Orthogonal Frequency Division Multiplexing (OFDM) systems. Wavelet transform is employed in modern cellular networks to remove the use of cyclic prefix, which leads to decreasing the bandwidth losses and the power of transmission. Wavelet based OFDM system is designed in order to overcome the drawbacks of OFDM system so that the proposed system is good candidate for next generation wireless communications.

Performance Evaluation of OFDM Based Link Using LabVIEW 2012

2016 ◽  
Vol 14 (4) ◽  
pp. 33-38
Author(s):  
G. Soni
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Cyclic Prefix ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Performance Parameters ◽  
Channel Fading ◽  
Ofdm System ◽  
Wireless System ◽  
Core Technology ◽  
Simulation Based

Abstract Background: Orthogonal Frequency Division Multiplexing (OFDM) has emerged as the core technology of the 4th generation mobile communication due to its capacity to combat channel fading also OFDM is highly spectral efficient. Methods/Statistical Analysis: LabVIEW 2012 is used to simulate and evaluate the performance of OFDM link. Bit Error Rate (BER) evaluation of discrete Fourier transform (DFT) based OFDM system is carried out in this work. The simulation based analysis is demonstrated by means of different modulation schemes like QPSK, 16-QAM for OFDM based wireless system. Findings: QPSK needs less SNR as compared to 16-QAM to achieve an acceptable BER Furthermore, the efficiency of OFDM increases with increase of cyclic prefix. In OFDM, ISI and ICI-interference reduced by implying cyclic prefix. Applications/Improvements: The performance analysis of orthogonal frequency division multiplexing is analyzed using LabVIEW 2012 based on performance parameters like cyclic prefix simulated at frequency of 2.4 GHz using FFT size 512, 1024.

scholarly journals Design and implementation of low power encoder incorporating adaptive modulation for multi user OFDM system

2018 ◽  
Vol 7 (1.9) ◽  
pp. 41
Author(s):  
K Jayaram ◽  
Dr C.Arun
Keyword(s):  
Wireless Communication ◽  
Low Power ◽  
Communication System ◽  
Orthogonal Frequency Division Multiplexing ◽  
Adaptive Modulation ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Ofdm System ◽  
Wireless Communication System ◽  
Design And Implementation

Wireless communication system is a key element in modern uninterupted data tramsnission and reception services. In this paper, multi user Orthogonal Frequency Division Multiplexing (OFDM) system is designed with low power encoder and adaptive modualtion architectures. The proposed multi user encoder architecture is designed in Verlog HDL and simulated in Modelsim simulator. Xilinx Project Navigator is used to evaluate the performance of the proposed architecture interms of power consumptions and hardware utilizations by implementing the architecture on different virtex processors.

scholarly journals Channel estimation of OFDM in C-band communication systems under different distribution conditions

2021 ◽  
Vol 23 (3) ◽  
pp. 1778
Author(s):  
Heba Abdul-Jaleel Al-Asady ◽  
Hassan Falah Fakhruldeen ◽  
Mustafa Qahtan Alsudani
Keyword(s):  
Fourier Transform ◽  
Channel Estimation ◽  
Fast Fourier Transform ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Ofdm System ◽  
High Data ◽  
High Efficient

<p>Orthogonal frequency division multiplexing (OFDM) is a transmission system that uses multiple orthogonal carriers that are sent out at the same time. OFDM is a technique for mobile and wireless communication that has high-efficient frequency utilization, high data-rate transmission, simple and efficient implementation using the fast Fourier transform (FFT) and the inverse fast Fourier transform (IFFT), and reduces inter symbol interference (ISI) by inserting cyclic prefix (CP). One of the most important approaches in an OFDM system is channel estimation. In this paper, the orthogonal frequency division multiplexing system with the Rayleigh channel module is analyzed for different areas. The proposed approach used large numbers of subcarriers to transmit the signals over 64-QAM modulation with pilot add channel estimation. The accuracy of the OFDM system is shown in the measuring of the relationships of peak power to the noise ratio and bit error rate.</p>

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.

scholarly journals A CCM-Based OFDM System with Low PAPR for Sparse Source

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Qinbiao Yang ◽  
Zulin Wang ◽  
Qin Huang
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Coded Modulation ◽  
High Peak ◽  
Frequency Division Multiplexing ◽  
Power Ratio ◽  
Frequency Division ◽  
Ofdm System ◽  
Simulation Results ◽  
Clipping And Filtering

Orthogonal frequency division multiplexing (OFDM) usually suffers high peak-to-average power ratio (PAPR). As shown in this paper, PAPR becomes even severe for sparse source due to many identical nonzero frequency OFDM symbols. Thus, this paper introduces compressive coded modulation (CCM) in order to restrain PAPR by reducing identical nonzero frequency symbols for sparse source. As a result, the proposed CCM-based OFDM system, together with iterative clipping and filtering, can efficiently restrain the high PAPR for sparse source. Simulation results show that it outperforms about 4 dB over the traditional OFDM system when source sparsity is 0.1.

Optimization and Simulation of OFDM System Based on Orthogonal Wavelet

2014 ◽  
Vol 548-549 ◽  
pp. 1221-1226
Author(s):  
Zeng You Sun ◽  
Fan Ming Zeng
Keyword(s):  
Fourier Transform ◽  
Discrete Fourier Transform ◽  
Orthogonal Frequency Division Multiplexing ◽  
Modulation Method ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Ofdm System ◽  
Orthogonal Wavelet ◽  
Optimization And Simulation

In order to reduce the Orthogonal Frequency division Multiplexing (OFDM) Inter-Carrier Interference (ICI), Put forward a kind of modulation method that based on the orthogonal frequency division multiplexing of orthogonal wavelet, Using orthogonal wavelet instead of discrete Fourier transform, optimize the design for OFDM systems, on the premise of without protection interval to reduce the system interference, using MATLAB to simulate the OFDM system, results show that the optimization of the OFDM can reduce the power of the ICI and Inter-symbol Interference (ISI) and improve the comprehensive anti-jamming of the OFDM system.

An Iterative Frequency Offset Estimation Algorithm for OFDM System

2013 ◽  
Vol 765-767 ◽  
pp. 2858-2861
Author(s):  
Feng Zheng ◽  
Yun Tang ◽  
Hang Liu
Keyword(s):  
Data Structure ◽  
Wireless Communications ◽  
Iterative Algorithm ◽  
Orthogonal Frequency Division Multiplexing ◽  
Estimation Algorithm ◽  
Frequency Offset ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Frequency Offset Estimation ◽  
Ofdm System

Orthogonal Frequency Division Multiplexing (OFDM) is considered as an important technique for future wireless communications. In addition, OFDM has a better performance at inter symbol interference (ISI). One of the major disadvantages of the multi-carrier modulation is about the sensitivity of the performance to a frequency offset. In this paper, we propose an iterative algorithm of frequency offset estimation for the OFDM system. The fundamental algorithm of our iterative algorithm is the frequency pilot aided algorithm. When we get a result with the fundamental algorithm every time, we use the result to estimate for a second time. The algorithm we proposed does not require some additional pilots or changing the data structure of the fundamental algorithm.

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