Estimation and Equalization of residual synchronization errors in CP-OTFS

10.36227/techrxiv.12581270 ◽

2020 ◽

Author(s):

Shashank Tiwari ◽

Vivek Rangamgari ◽

suvra Das ◽

subhas chandra mondal

Keyword(s):

Interface Design ◽

Carrier Frequency Offset ◽

Estimation Method ◽

Channel Equalization ◽

Synchronization Errors ◽

Timing Offset ◽

Air Interface ◽

Compensation Methods ◽

Seamless Transition ◽

Future Publication

In this work, we analyze the effect of residual frame timing offset and carrier frequency offset along with the presence of fractional Doppler on the bit error rate performance of OFTS system. We show in this work that channel equalization with appropriate channel estimates can compensate for the combined effect of the time-varying multipath channel (TVMC) as well as residual synchronization errors. We<br>also present a unique time-domain channel estimation method for OTFS, which can be used along with the above-mentioned channel equalization. It is seen from the extensive Monte Carlo simulation results of the LDPC coded OTFS system that the estimation and compensation methods presented here provide necessary resilience properties to OTFS against the effects of TVMC channel and residual<br><div>synchronization errors. A unified signal processing flow for OTFS and OFDM is also described in this work to motivate studies on coexistence between the two as well as to encourage investigations on a seamless transition from OFDM based system to OTFS based systems for future air interface design.</div><div><br></div><div><b>This Work is submiited to an IEEE Journal for possible future publication.</b><br></div>

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Robust Preamble-Based Timing Synchronization for OFDM Systems

Journal of Computer Networks and Communications ◽

10.1155/2017/9319272 ◽

2017 ◽

Vol 2017 ◽

pp. 1-7 ◽

Cited By ~ 2

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.

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Pilot Based Channel Estimation and Synchronization in OFDM System

Journal of Engineering ◽

10.31026/j.eng.2020.06.04 ◽

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.

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

10.21203/rs.3.rs-747120/v1 ◽

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.

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