scholarly journals Performance of MIMO FBMC-OQAM and MIMO OFDM-QAM under time Synchronization Errors in Perfect CSI and Imperfect CSI

2020 ◽  
Vol 9 (6) ◽  
pp. 17-23
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Filter Bank ◽  
Time Synchronization ◽  
Imperfect Csi ◽  
Synchronization Errors ◽  
Timing Offset ◽  
Mimo Ofdm ◽  
Limited Frequency ◽  
Amplitude Modulator ◽  
Time Offset

The requirement of flexible allocation of available limited frequency resources led to rethink the possibilities to find an substitute to Orthogonal Frequency Division Multiplexing (OFDM) [1], which can also meet the necessities of future wireless communication. In this paper, we have compared one such alternative to OFDM, which is Filter Bank Multi Carrier (FBMC) [2] with Offset Quadrature Amplitude Modulator (OQAM) . The BER performance of OQAM based MIMO FBMC compared with QAM based MIMO OFDM for various channels conditions and using different prototype filters [3] for FBMC and under the influence of Timing Offset errors with perfect CSI and imperfect CSI. Implementation of MIMO into OQAM-FBMC has a computational complexity compared to MIMO OFDM and we have used block coded MIMO OQAMFBMC for simulation. Three prototype filters RRC, Hermite and PHYDYAS are used to analyze the performance of OQAMFBMC in relations of Signal to Interference Ratio under time offset and found that performance of PHYDYAS prototype filter outperforms RRC and Hermite prototype filters.

Time and Frequency Synchronization for MIMO-OFDM Systems

2013 ◽  
Vol 321-324 ◽  
pp. 2888-2891
Author(s):  
Jing Peng Gao ◽  
Chao Qun Wu ◽  
Dan Feng Zhao
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Carrier Frequency Offset ◽  
Time Synchronization ◽  
Multiple Input Multiple Output ◽  
Frequency Offset ◽  
Time Instant ◽  
Frequency Synchronization ◽  
Ofdm Systems ◽  
Frequency Offset Estimation ◽  
Mimo Ofdm

Any carrier frequency offset will cause a loss of subcarrier orthogonality which results in ICI and hence performance degrades severely in MIMO-OFDM systems. In this paper, a time and frequency synchronization solution for multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems is proposed. The synchronization is achieved using one Constant Amplitude Zero Auto Correlation (CAZAC) sequence-based preamble which is simultaneously transmitted from all transmit antennas in the same OFDM time instant. The synchronization is accomplished sequentially by coarse time synchronization, fractional frequency offset estimation, integral frequency offset estimation and fine time synchronization. The simulation shows that the proposed algorithm can estimate the timing and frequency offsets efficiently in MIMO-OFDM systems, especially in low signal-to-noise ratio condition.

scholarly journals Pilot Based Channel Estimation and Synchronization in OFDM System

2020 ◽  
Vol 26 (6) ◽  
pp. 50-59
Author(s):  
Mahmood Mohmmmed saeed Abdul Majed ◽  
Buthaina Mosa Omran
Keyword(s):  
Channel Estimation ◽  
Orthogonal Frequency Division Multiplexing ◽  
Carrier Frequency Offset ◽  
Estimation Method ◽  
Frequency Division ◽  
Ofdm System ◽  
Synchronization Errors ◽  
Rayleigh Channel ◽  
Significant Performance ◽  
Time Offset

Channel estimation and synchronization are considered the most challenging issues in Orthogonal Frequency Division Multiplexing (OFDM) system. OFDM is highly affected by synchronization errors that cause reduction in subcarriers orthogonality, leading to significant performance degradation. The synchronization errors cause two issues: Symbol Time Offset (STO), which produces inter symbol interference (ISI) and Carrier Frequency Offset (CFO), which results in inter carrier interference (ICI). The aim of the research is to simulate Comb type pilot based channel estimation for OFDM system showing the effect of pilot numbers on the channel estimation performance and propose a modified estimation method for STO with less number of pilot to mitigate ISI effect. Channel estimation is simulated for different pilot number with 16QAM modulation in Ped-A Rayleigh channel. The STO effect assumed less than the cyclic prefix length to minimize ISI and maintain the orthogonality between subcarriers. The simulation results show that the high number of pilots are needed to achieve good channel estimation in case no synchronization used while similar results are achieved with smaller number of pilots if the propose modification on the synchronization method are used aligned with the channel estimation. The proposed system is evaluated in terms of BER and SNR.

scholarly journals Characterization of GFDM Signal with Timing Offset, CFO, Non-Linearity, and PN

2021 ◽  
Author(s):  
Fereshteh Yazdani ◽  
Abbas Mohammadi ◽  
Abdolali Abdipour ◽  
Mohammad Kazemi
Keyword(s):  
Power Amplifier ◽  
Orthogonal Frequency Division Multiplexing ◽  
Carrier Frequency Offset ◽  
Matched Filter ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Synchronization Errors ◽  
Timing Offset ◽  
Nonlinear Power Amplifier

Abstract In this paper, we study the joint effects of timing offset (TO), carrier frequency offset (CFO), nonlinear power amplifier distortion, and phase noise (PN) on generalized frequency division multiplexing (GFDM) system. Closed form expressions for signal-to-interference ratio (SIR) at GFDM receiver with synchronization errors and PN using a nonlinear power amplifier is derived. Then, we have been conducted simulation studies to compare the performance of GFDM systems with orthogonal frequency division multiplexing (OFDM) systems using matched filter (MF) and zero forcing (ZF), in presence of these impairments. The results show that GFDM systems are more robust against TO and PN while they are more sensitive to CFO and nonlinear distortion compared to OFDM systems.

Improving Space-Time-Frequency MIMO-OFDM with ICI Self-Cancellation Scheme using Least Square Error Estimator

2015 ◽  
Vol 12 (1) ◽  
pp. 25
Author(s):  
Nur Farahiah Ibrahim ◽  
Zahari Abu Bakar ◽  
Azlina Idris
Keyword(s):  
Channel Estimation ◽  
Orthogonal Frequency Division Multiplexing ◽  
Symbol Error Rate ◽  
Space Time ◽  
Least Square ◽  
Error Estimator ◽  
Frequency Diversity ◽  
Time Frequency ◽  
Mimo Ofdm ◽  
Subcarrier Mapping

Channel estimation techniques for Multiple-input Multiple-output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) based on comb type pilot arrangement with least-square error (LSE) estimator was investigated with space-time-frequency (STF) diversity implementation. The frequency offset in OFDM effected its performance. This was mitigated with the implementation of the presented inter-carrier interference self-cancellation (ICI-SC) techniques and different space-time subcarrier mapping. STF block coding in the system exploits the spatial, temporal and frequency diversity to improve performance. Estimated channel was fed into a decoder which combined the STF decoding together with the estimated channel coefficients using LSE estimator for equalization. The performance of the system was compared by measuring the symbol error rate with a PSK-16 and PSK-32. The results show that subcarrier mapping together with ICI-SC were able to increase the system performance. Introduction of channel estimation was also able to estimate the channel coefficient at only 5dB difference with a perfectly known channel.

A companding approach for PAPR suppression in OFDM based massive MIMO system

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ajay Kumar Yadav ◽  
Pritam Keshari Sahoo ◽  
Yogendra Kumar Prajapati
Keyword(s):  
Massive Mimo ◽  
Orthogonal Frequency Division Multiplexing ◽  
Mimo System ◽  
Multiple Input Multiple Output ◽  
Average Power ◽  
Base Station ◽  
Convex Optimization Problem ◽  
Multiple Input ◽  
Input Multiple Output ◽  
Mimo Ofdm

Abstract Orthogonal frequency division multiplexing (OFDM) based massive multiuser (MU) multiple input multiple output (MIMO) system is popularly known as high peak-to-average power ratio (PAPR) issue. The OFDM-based massive MIMO system exhibits large number of antennas at Base Station (BS) due to the use of large number of high-power amplifiers (HPA). High PAPR causes HPAs to work in a nonlinear region, and hardware cost of nonlinear HPAs are very high and also power inefficient. Hence, to tackle this problem, this manuscript suggests a novel scheme based on the joint MU precoding and PAPR minimization (PP) expressed as a convex optimization problem solved by steepest gradient descent (GD) with μ-law companding approach. Therefore, we develop a new scheme mentioned to as MU-PP-GDs with μ-law companding to minimize PAPR by compressing and enlarging of massive MIMO OFDM signals simultaneously. At CCDF = 10−3, the proposed scheme (MU-PP-GDs with μ-law companding for Iterations = 100) minimizes the PAPR to 3.70 dB which is better than that of MU-PP-GDs, (iteration = 100) as shown in simulation results.

Performance Analysis of an Area Efficient and Low Power MOD-R2MDC FFT for MIMO OFDM

2014 ◽  
Vol 573 ◽  
pp. 176-180
Author(s):  
G. Kavitha ◽  
B. Kirthiga ◽  
N. Kirubanandasarathy
Keyword(s):  
Low Power ◽  
Orthogonal Frequency Division Multiplexing ◽  
Ofdm System ◽  
Description Language ◽  
Fft Processor ◽  
Synthesis Tool ◽  
Mimo Ofdm ◽  
Hardware Description ◽  
Fft Algorithms ◽  
Area Efficient

In this paper, an area-efficient low power fast fourier transform (FFT) processor is proposed for multi input multi output-orthogonal frequency division multiplexing (MIMO-OFDM) in wireless communication system. It consists of a modified architecture of radix-2 algorithm which is described as modified radix-2 multipath delay commutation (MOD-R2MDC). The OFDM receiver with modified R2MDC (MOD-R2MDC) FFT was designed by Hardware Description Language (HDL) coding The Xilinx ISE Design Suite 10.1 is used as a synthesis tool for getting the power and area. The Model-Sim 6.3c is used for simulation. Also the existing OFDM system has been tested with these FFT algorithms and their performances were analyzed with respect to occupancy area in FPGA and power consumption. A low-power and area efficient architecture enables the real-time operations of MIMO OFDM system.

scholarly journals Robust Preamble-Based Timing Synchronization for OFDM Systems

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Yun Liu ◽  
Fei Ji ◽  
Hua Yu ◽  
Dehuan Wan ◽  
Fangjiong Chen ◽  
...  
Keyword(s):  
Fading Channels ◽  
Orthogonal Frequency Division Multiplexing ◽  
Carrier Frequency Offset ◽  
Estimation Method ◽  
Multipath Fading ◽  
New Method ◽  
Timing Synchronization ◽  
Ofdm Systems ◽  
Multipath Fading Channels ◽  
Timing Offset

This study presents a novel preamble-based timing offset estimation method for orthogonal frequency division multiplexing (OFDM) systems. The proposed method is robust, immune to the carrier frequency offset (CFO), and independent of the structure of the preamble. The performance of the new method is demonstrated in terms of mean square error (MSE) obtained by simulation in multipath fading channels. The results indicate that the new method significantly improves timing performance in comparison with existing methods.

scholarly journals Análisis de la técnica UFMC en un canal multitrayecto y usando estimación de canal

2021 ◽  
Vol 9 (17) ◽  
pp. 26-39
Author(s):  
Hugo Wladimir Iza Benítez ◽  
Diego Javier Reinoso Chisaguano
Keyword(s):  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Filter Bank ◽  
Estimation Method ◽  
Wireless Communication Systems ◽  
Ofdm Systems ◽  
Matlab Simulation ◽  
Fifth Generation ◽  
Power Spectral ◽  
Filter Bank Multicarrier

UFMC (Universal Filtered Multi-Carrier) is a novel multi-carrier transmission technique that aims to replace the OFDM (Orthogonal Frequency Division Multiplexing) modulation technique for fifth generation (5G) wireless communication systems. UFMC, being a generalization of OFDM and FBMC (Filter Bank Multicarrier), combines the advantages of these systems and at the same time avoids their main disadvantages. Using a Matlab simulation, this article presents an analysis of the robustness of UFMC against fading effects of multipath channels without using a CP (cyclic prefix). The behavior of the UFMC system is analyzed in terms of the PSD (Power Spectral Density), BER (Bit Error Rate) and MSE (Mean Square Error). The results show that UFMC reduces the out-band side lobes produced in the PSD of the processed signal. Also, it is shown that the pilot-assisted channel estimation method applied in OFDM systems can also be applied in UFMC systems.

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