scholarly journals Faster-than-Nyquist Signal Processing Based on Unequal Error Probability for High-Throughput Wireless Communications

2019 ◽  
Vol 9 (12) ◽  
pp. 2413
Author(s):  
Chang-Uk Baek ◽  
Ji-Won Jung
Keyword(s):  
Signal Processing ◽  
Performance Improvement ◽  
Orthogonal Frequency Division Multiplexing ◽  
Error Probability ◽  
Probability Method ◽  
Frequency Division ◽  
Improve Performance ◽  
Group A ◽  
Nyquist Rate ◽  
Better Than

Faster-than-Nyquist (FTN) signal processing, which transmits signals faster than the Nyquist rate, is a representative method for improving throughput efficiency sacrificed performance degradation due to inter-symbol interference. To overcome this problem, this paper proposed FTN signal processing based on the unequal error probability to improve performance. The unequal error probability method divides encoded bits into groups according to priority, and FTN interference rates are differently applied to each group. A lower FTN interference ratio is allocated to the group to which high-priority encoded bits belong and a higher FTN interference ratio is allocated to the group to which low-priority encoded bits belong, thus performance improvement can be obtained compared to the conventional FTN method, with the same interference ratio. In addition, we applied the proposed FTN signal processing, based on the unequal error probability method, to the OFDM (orthogonal frequency division multiplexing) system in multipath channel environments. In the simulations, the performance of the proposed method was better than that of the conventional FTN method by about 0.2 dB to 0.3 dB, with an interference ratio of 20%, 30%, and 40%. In addition, in multipath channels, we confirmed that by applying the proposed unequal error probability, the OFDM-FTN method improves performance to a larger extent than the conventional OFDM-FTN method.

scholarly journals Performance analysis of OFDMA and SC-FDMA

2017 ◽  
Vol 8 (2) ◽  
pp. 113-116 ◽  
Author(s):  
M. Al-Rawi
Keyword(s):  
Carrier Frequency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Multiple Access ◽  
High Speed ◽  
Minimum Mean Square Error ◽  
Frequency Division ◽  
International Telecommunication Union ◽  
Single Carrier ◽  
Main Challenge ◽  
Better Than

The main challenge in any high-speed digital communication system is how to maximize the data rate with minimizing the bit error rate. Several techniques have been developed to achieve this point. Some of these techniques are orthogonal frequency division multiplexing (OFDM), single-carrier frequency domain equalization (SC-FDE), orthogonal frequency division multiple access (OFDMA), and single-carrier frequency division multiple access (SC-FDMA). These four techniques are described briefly in this paper. Also, the paper measures the performances of OFDMA and SC-FDMA systems over international telecommunication union (ITU) vehicular-A channel using minimum mean square error (MMSE) equalization. Simulation results show that the performances with interleaved mapping outperform that with localized mapping. Also, the performances with quadrature phase shift keying (QPSK) are better than that with 16-ary quadrature amplitude modulation (16QAM). In addition, the performance of SC-FDMA is better than that of OFDMA, when QPSK is used, but the latter is little bit better than that of SC-FDMA when 16QAM is used.

Self-improved grey wolf optimization for estimating carrier frequency offset in SCM-OFDM systems

2020 ◽  
Vol 16 (1) ◽  
pp. 53-73
Author(s):  
Rashmi N. ◽  
Mrinal Sarvagya
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Carrier Frequency Offset ◽  
State Of The Art ◽  
Frequency Division ◽  
Grey Wolf ◽  
Ofdm System ◽  
Grey Wolf Optimization ◽  
Content Type ◽  
Transmitted Signal ◽  
Better Than

Purpose The purpose of this paper is to demonstrate a proficiency for accomplishing optimal CFO and keep down the error among the received and transmitted signal. Orthogonal frequency-division multiplexing (OFDM) is considered as an attractive modulation scheme that could be adopted in wireless communication systems owing to its reliability in opposition to multipath interruptions under different subchannels. Carrier frequency offset (CFO) establishes inter-carrier interference that devastates the orthogonality between the subcarriers and fluctuates the preferred signal and minimizes the effectual signal-to-noise ratio (SNR). This results in corrupted system performance. For sustaining the subcarriers’ orthogonality, timing errors and CFOs have to be approximated and sufficiently compensated for. Single carrier modulation (SCM) is a major feature for efficient OFDM system. Design/methodology/approach This paper introduces a novel superposition coded modulation-orthogonal frequency-division multiplexing (SCM-OFDM) system with optimal CFO estimation using advanced optimization algorithm. The effectiveness of SCM-OFDM is validated by correlating the transmitted and received signal. Hence, the primary objective of the current research work is to reduce the error among the transmitted and received signal. The received signal involves CFO, which has to be tuned properly to get the signal as closest as possible with transmitted signal. The optimization or tuning of CFO is done by improved grey wolf optimization (GWO) called GWO with self-adaptiveness (GWO-SA). Further, it carries the performance comparison of proposed model with state-of-the-art models with the analysis on bit error rate (BER) and mean square error (MSE), thus validating the system’s performance. Findings From the analysis, BER of the proposed and conventional schemes for CFO at 0.25 was determined, where the adopted scheme at 10th SNR was 99.6 per cent better than maximum likelihood, 99.6 per cent better than least mean square (LMS), 99.3 per cent better than particle swarm optimization (PSO), 75 per cent better than genetic algorithm (GA) and 25 per cent better than GWO algorithms. Moreover, MSE at 1st SNR, the proposed GWO-SA scheme, is 4.62 per cent better than LMS, 60.1 per cent better than PSO, 37.82 better than GA and 67.85 per cent better than GWO algorithms. Hence, it is confirmed that the performance of SCM-OFDM system with GWO-SA-based CFO estimation outperformed the state-of-the-art techniques. Originality/value This paper presents a technique for attaining optimal CFO and to minimize the error among the received and transmitted signal. This is the first work that uses GWO-SA for attaining optimal CFO.

scholarly journals New Signal Constellation Pairs for the ZTM-OFDM-IM System

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Shuang Li ◽  
Seog Geun Kang
Keyword(s):  
Fading Channels ◽  
Performance Improvement ◽  
Orthogonal Frequency Division Multiplexing ◽  
Euclidean Distance ◽  
Frequency Division ◽  
Error Performance ◽  
Dual Mode ◽  
Signal Constellation ◽  
Frequency Selective Fading ◽  
The One

In this paper, we investigate new signal constellation pairs for mapping active subcarriers of the zero-padded trimode orthogonal frequency division multiplexing with index modulation (ZTM-OFDM-IM) systems. In the presented system, one of a constellation pair is the same as the one used in the previous work, and the other is a constellation larger than the one used in the previous work. It increases the minimum Euclidean distance between the subblocks of the ZTM-OFDM-IM system with new constellation pairs under the constraint of the same spectral efficiency. Computer simulation in AWGN and frequency-selective fading channels shows that the new ZTM-OFDM-IM system has a much lower bit error rate than OFDM-IM and dual-mode OFDM-IM and slightly outperforms the system with conventional constellation pairs. Since the proposed constellation pairs prove the error performance improvement of the system, it is considered that a further study on generalized design of the constellation pair for the ZTM-OFDM-IM system is necessary in the future.

scholarly journals Performance of Filtered OFDM Over Different Fading Channels

2020 ◽  
Vol 9 (4) ◽  
pp. 1959-1962
Keyword(s):  
Fading Channels ◽  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Frequency Division ◽  
Spectral Leakage ◽  
Band Emission ◽  
Rician Channel ◽  
Ber Performance ◽  
Better Than ◽  
The Ideal

Orthogonal frequency division multiplexing (OFDM) schemes are used extensively nowadays in large number of practical systems, but OFDM may not be the ideal solution for 5G scenarios because OFDM has high Out of band emission (OOBE) due to high spectral leakage and high peak to average power ratio (PAPR). Therefore Filtered OFDM (F-OFDM), which uses sub band filtering, is proposed as the most flexible waveform for 5G. However there is no work listed in the literature so far that compares the bit error rate (BER) performance of F-OFDM and conventional OFDM in AWGN, Rayleigh and Rician channel. This paper presents the simulation results on the BER performance of F-OFDM and OFDM in presence of AWGN, Rayleigh and Rician channel. The comparison is also done in terms of OOBE and PAPR factor. Results indicate that F-OFDM shows significantly less spectral leakage with same performance in terms of BER compared to conventional OFDM. However for the cases considered, OFDM performance is slightly better than F-OFDM in terms of PAPR factor.

scholarly journals Comparing f-OFDM and OFDM Performance for MIMO Systems Considering a 5G Scenario

2019 ◽  
Author(s):  
Felipe Augusto Pereira de Figueiredo ◽  
Nathália F. T. Aniceto ◽  
Jorge Seki ◽  
Ingrid Moerman ◽  
Gustavo Fraidenraich
Keyword(s):  
Mobile Communications ◽  
Orthogonal Frequency Division Multiplexing ◽  
Error Probability ◽  
Mimo Systems ◽  
Radio Spectrum ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Primary Users ◽  
Band Emission ◽  
Spectral Localization

The advances mobile communications has seen in recent years has rendered the radio spectrum a limited and, hence, an expensive resource. Therefore, technologies that support unlicensed access to spectrum are needed. Therefore, the adoption of novel modulation schemes becomes of utmost importance to obtain better spectral-localization and reduce the OOBE (\textit{Out of Band Emission}) inherent to OFDM (\textit{Orthogonal Frequency Division Multiplexing}) and, consequently, mitigating the interference between secondary (\textit{unlicensed}) and primary users. In this scenario, we assess the gain in the bit error probability using f-OFDM (\textit{filtered-OFDM}) in MIMO systems, both used in the 5G RANGE project.

scholarly journals Study of the Discrete Wavelet Transform Based Designed System Under Different Simulation Conditions

2020 ◽  
Vol 14 ◽  
Keyword(s):  
Signal Processing ◽  
Wavelet Transform ◽  
Discrete Wavelet Transform ◽  
Amplitude Modulation ◽  
Orthogonal Frequency Division Multiplexing ◽  
Pulse Amplitude ◽  
Discrete Wavelet ◽  
Pulse Amplitude Modulation ◽  
Frequency Division Multiplexing ◽  
Frequency Division

Wavelet Transforms is an Important Part of, Systems Theory and Signal Processing and finds numerous important applications in Science and Engineering. In this paper, we investigated the performance of proposed scheme coded Discrete wavelet transform based Orthogonal frequency division multiplexing scheme over Additive white Gaussian noise channel using Pulse Amplitude Modulation in terms of Energy bits per noise ratio values. The simulation has been done using MATLAB software and results are compared with ½ rate convolution coded Discrete wavelet transform based Orthogonal frequency division multiplexing system. It is found by MATLAB simulations that the performance of proposed scheme coded Discrete wavelet transform based Orthogonal frequency division multiplexing outperforms than that of ½ rate convolution encoded Discrete wavelet transform based Orthogonal frequency division multiplexing with 16-Pulse Amplitude Modulation. Along with this, different orders of reverse biorthogonal and biorthogonal wavelets are implemented to simulate the proposed system with 16-Pulse Amplitude Modulation scheme. The performance of proposed system is compared and it is found that proposed system performs better than conventional system under all different simulation conditions. This study finds important applications in Signal Processing.

scholarly journals Comparing f-OFDM and OFDM Performance for MIMO Systems Considering a 5G Scenario

2019 ◽  
Author(s):  
Felipe Augusto Pereira de Figueiredo ◽  
Nathália F. T. Aniceto ◽  
Jorge Seki ◽  
Ingrid Moerman ◽  
Gustavo Fraidenraich
Keyword(s):  
Mobile Communications ◽  
Orthogonal Frequency Division Multiplexing ◽  
Error Probability ◽  
Mimo Systems ◽  
Radio Spectrum ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Primary Users ◽  
Band Emission ◽  
Spectral Localization

The advances mobile communications has seen in recent years has rendered the radio spectrum a limited and, hence, an expensive resource. Therefore, technologies that support unlicensed access to spectrum are needed. Therefore, the adoption of novel modulation schemes becomes of utmost importance to obtain better spectral-localization and reduce the OOBE (\textit{Out of Band Emission}) inherent to OFDM (\textit{Orthogonal Frequency Division Multiplexing}) and, consequently, mitigating the interference between secondary (\textit{unlicensed}) and primary users. In this scenario, we assess the gain in the bit error probability using f-OFDM (\textit{filtered-OFDM}) in MIMO systems, both used in the 5G RANGE project.

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