Maximum Likelihood Time Synchronization for Zero-Padded OFDM

Roshandeh, Koosha Pourtahmasi; Mohammadkarimi, Mostafa; Ardakani, Masoud

doi:10.1109/tsp.2020.3048231

Cited by 5 publications

(10 citation statements)

References 32 publications

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“…Such techniques, though simple, have a poor probability of correct estimation, called lock-in probability. On the other hand, a mathematically heavy approach via maximum likelihood (ML) technique was proposed in [ 20 ]. However, the approach in [ 20 ] is highly complex, which hinders its implementation in many practical scenarios where the user has limited computational capacity, e.g., mobile users and sensors.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, a mathematically heavy approach via maximum likelihood (ML) technique was proposed in [ 20 ]. However, the approach in [ 20 ] is highly complex, which hinders its implementation in many practical scenarios where the user has limited computational capacity, e.g., mobile users and sensors. Moreover, the proposed method in [ 20 ] cannot be used for signal-to-noise ratio (SNR)s less than 5 dB due to the accumulation of numerical errors.…”

Section: Introductionmentioning

confidence: 99%

“…However, the approach in [ 20 ] is highly complex, which hinders its implementation in many practical scenarios where the user has limited computational capacity, e.g., mobile users and sensors. Moreover, the proposed method in [ 20 ] cannot be used for signal-to-noise ratio (SNR)s less than 5 dB due to the accumulation of numerical errors. In an attempt to address these issues, authors in [ 21 ] proposed two methods based on the method of moments.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the proposed method in [ 20 ] cannot be used for signal-to-noise ratio (SNR)s less than 5 dB due to the accumulation of numerical errors. In an attempt to address these issues, authors in [ 21 ] proposed two methods based on the method of moments. In such techniques, the timing offset is estimated by equating the theoretical moments of the received samples and their natural moments.…”

Section: Introductionmentioning

confidence: 99%

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Joint Method of Moments (JMoM) and Successive Moment Cancellation (SMC) Multiuser Time Synchronization for ZP-OFDM-Based Waveforms Applicable to Joint Communication and Sensing

Roshandeh

Mohammadkarimi

Ardakani

2023

Sensors

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It has been recently shown that zero padding (ZP)-orthogonal frequency-division multiplexing (OFDM) is a promising candidate for 6G wireless systems requiring joint communication and sensing. In this paper, we consider a multiuser uplink scenario where users are separated in power domain, i.e., non-orthogonal multiple access (NOMA), and use ZP-OFDM signals. The uplink transmission is grant-free and users are allowed to transmit asynchronously. In this setup, we address the problem of time synchronization by estimating the timing offset (TO) of all the users. We propose two non-data-aided (NDA) estimators, i.e., the joint method of moment (JMoM) and the successive moment cancellation (SMC), that employ the periodicity of the second order moment (SoM) of the received samples for TO estimation. Moreover, the coding assisted (CA) version of the proposed estimators, i.e., CA-JMoM and CA-SMC, are developed for the case of short observation samples. We also extend the proposed estimators to multiuser multiple-input multiple-output (MIMO) systems. The effectiveness of the proposed estimators is evaluated in terms of lock-in probability under various practical scenarios. Simulation results show that the JMoM estimator can reach the lock-in probability of one for the moderate range of Eb/N0 values. While existing NDA TO estimators in the literature either offer low lock-in probability, high computational complexity that prevents them from being employed in MIMO systems, or are designed for single-user scenarios, the proposed estimators in this paper address all of these issues.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Joint Method of Moments (JMoM) and Successive Moment Cancellation (SMC) Multiuser Time Synchronization for ZP-OFDM-Based Waveforms Applicable to Joint Communication and Sensing

Roshandeh

Mohammadkarimi

Ardakani

2023

Sensors

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“…OFDM variants are broadly classified into cyclic prefix (CP) OFDM, known symbol padding (KSP) OFDM [ 8 , 9 , 10 , 11 ], zero padding (ZP) OFDM [ 12 , 13 ], and unique word (UW) OFDM [ 14 , 15 ]. They all have been the focus of investigation among researchers for the last couple of decades.…”

Section: Introductionmentioning

confidence: 99%

BER Reduction and Capacity Enhancement with Novel Guard Sequence Selection for Multi-Carrier Communication

Ologun

Shah

et al. 2022

Sensors

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Orthogonal frequency division multiplexing (OFDM) is an efficient multicarrier scheme that uses different types of guard intervals such as cyclic prefix (CP) and known symbol padding (KSP) (zero padding (ZP), unique word (UW), etc.) in block formation. Among these guard intervals, CP varies for each block, while other guard intervals remain fixed from block to block. These guard intervals efficiently perform channel estimation, synchronization and remove inter-block interference (IBI); nevertheless, none of the existing schemes develop any relationship between the guard interval (sequence) and the data symbols on different subcarriers of the OFDM block. We present a new idea of selecting the guard interval based on the data symbols of a subset of subcarriers in the block and exploit the high auto-correlation of the selected guard sequence to improve the bit error rate (BER) performance of the system. The results based on a fair comparison show that our enhanced orthogonal frequency division multiplexing (eOFDM) scheme inherits significant improvements in BER and the capacity of a multicarrier system as compared to the existing techniques.

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CNN-aided timing synchronization in OFDM systems by exploiting lightweight cascaded mode

et al. 2024

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Maximum Likelihood Time Synchronization for Zero-Padded OFDM

Cited by 5 publications

References 32 publications

Joint Method of Moments (JMoM) and Successive Moment Cancellation (SMC) Multiuser Time Synchronization for ZP-OFDM-Based Waveforms Applicable to Joint Communication and Sensing

Joint Method of Moments (JMoM) and Successive Moment Cancellation (SMC) Multiuser Time Synchronization for ZP-OFDM-Based Waveforms Applicable to Joint Communication and Sensing

BER Reduction and Capacity Enhancement with Novel Guard Sequence Selection for Multi-Carrier Communication

CNN-aided timing synchronization in OFDM systems by exploiting lightweight cascaded mode

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