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

Pourtahmasi Roshandeh, Koosha (University of Alberta)
Mohammadkarimi, M. (TU Delft Signal Processing Systems)
Ardakani, Masoud (University of Alberta)

2023

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 (Formula presented.) 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.

CA-SMC
coding assisted (CA)-JMoM
ISAC
JCAS
joint method of moments (JMoM) 6G
MIMO
multiuser
NOMA
non-data-aided
OFDM
second order moment (SoM)
successive moment cancellation (SMC)
time synchronization
zero-padded

http://resolver.tudelft.nl/uuid:aea99726-1c09-46db-be1c-2f4cc490996d

https://doi.org/10.3390/s23073660

1424-8220

Sensors, 23 (7)

Institutional Repository

journal article

© 2023 Koosha Pourtahmasi Roshandeh, M. Mohammadkarimi, Masoud Ardakani