Interference cancellation for faster-than-nyquist wireless communications

Tong, Mingfei

Interference cancellation for faster-than-nyquist wireless communications

Tong, Mingfei

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Publication Type:: Thesis
Issue Date:: 2025

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Field	Value	Language
dc.contributor.author	Tong, Mingfei
dc.date.accessioned	2025-12-18T03:41:16Z
dc.date.available	2025-12-18T03:41:16Z
dc.date.issued	2025
dc.identifier.uri	http://hdl.handle.net/10453/190985
dc.description	University of Technology Sydney. Faculty of Engineering and Information Technology.	en_US.UTF-8
dc.description.abstract	The transition to sixth-generation (6G) networks promises transformative advancements in speed (up to 1 Tbps), spectral efficiency (over 100 bits/Hz), latency, and connectivity. Faster-than-Nyquist (FTN) signalling emerges as a key enabler, boosting spectral efficiency by intentionally violating the Nyquist criterion, albeit introducing inter-symbol interference (ISI). This thesis develops a low-complexity, high-performance FTN system with practical feasibility, addressing critical challenges in ISI cancellation, channel adaptability, and hardware impairments. A novel frame-by-frame decision-directed successive interference cancellation (DDSIC) scheme is proposed, integrating frequency-domain minimum-mean-square-error (FD-MMSE) equalisation. Compared to existing methods, DDSIC achieves superior bit error rate (BER) performance with reduced computational complexity, particularly under high-order modulation. To enhance real-world applicability, the system is tested under multipath fast-fading channels, where rapid channel state information (CSI) variations and Doppler shifts degrade performance. Traditional DDSIC, reliant on static CSI, is augmented with an adaptive transmission precoding (ATPC) method to counteract time-varying distortions. Simulations confirm ATPC’s robustness in dynamic environments. Beyond channel challenges, hardware imperfections like I/Q imbalance (IQI) in radio frequency (RF) front-ends are addressed. IQI causes image band interference, particularly in direct-conversion architectures. This work introduces an expanded signal model analyzing both primary and image band components, enabling joint suppression of IQI and ISI. The proposed DDSIC framework mitigates IQI to near-zero levels while maintaining high performance in multipath fading. Overall, the core contributions of this thesis lie in three areas: (i) the development of a low-complexity DDSIC algorithm for effective ISI cancellation; (ii) the enhancement of system adaptability to fast-fading channels through ATPC; and (iii) the integration of IQI mitigation within the FTN framework. Extensive simulations validate the system’s performance across diverse wireless environments, bridging the gap between theoretical FTN capacity gains and practical 6G deployment readiness.	en_US.UTF-8
dc.format	Thesis (PhD)
dc.language.iso	en_US	en_US.UTF-8
dc.relation	https://opus.lib.uts.edu.au/bitstream/10453/190985/1/thesis.pdf
dc.rights	info:eu-repo/semantics/openAccess
dc.rights	The author owns the copyright in this thesis including all reproduction and reuse rights for the work. The work may not be altered without the permission of the copyright owner. Attribution is essential when quoting or paraphrasing from this thesis.
dc.rights	© 2025 Mingfei Tong
dc.rights	au.edu.uts.lib/cph
dc.title	Interference cancellation for faster-than-nyquist wireless communications	en_US.UTF-8
dc.type	Thesis
utslib.copyright.status	open_access	*

Abstract:

The transition to sixth-generation (6G) networks promises transformative advancements in speed (up to 1 Tbps), spectral efficiency (over 100 bits/Hz), latency, and connectivity. Faster-than-Nyquist (FTN) signalling emerges as a key enabler, boosting spectral efficiency by intentionally violating the Nyquist criterion, albeit introducing inter-symbol interference (ISI). This thesis develops a low-complexity, high-performance FTN system with practical feasibility, addressing critical challenges in ISI cancellation, channel adaptability, and hardware impairments. A novel frame-by-frame decision-directed successive interference cancellation (DDSIC) scheme is proposed, integrating frequency-domain minimum-mean-square-error (FD-MMSE) equalisation. Compared to existing methods, DDSIC achieves superior bit error rate (BER) performance with reduced computational complexity, particularly under high-order modulation. To enhance real-world applicability, the system is tested under multipath fast-fading channels, where rapid channel state information (CSI) variations and Doppler shifts degrade performance. Traditional DDSIC, reliant on static CSI, is augmented with an adaptive transmission precoding (ATPC) method to counteract time-varying distortions. Simulations confirm ATPC’s robustness in dynamic environments. Beyond channel challenges, hardware imperfections like I/Q imbalance (IQI) in radio frequency (RF) front-ends are addressed. IQI causes image band interference, particularly in direct-conversion architectures. This work introduces an expanded signal model analyzing both primary and image band components, enabling joint suppression of IQI and ISI. The proposed DDSIC framework mitigates IQI to near-zero levels while maintaining high performance in multipath fading. Overall, the core contributions of this thesis lie in three areas: (i) the development of a low-complexity DDSIC algorithm for effective ISI cancellation; (ii) the enhancement of system adaptability to fast-fading channels through ATPC; and (iii) the integration of IQI mitigation within the FTN framework. Extensive simulations validate the system’s performance across diverse wireless environments, bridging the gap between theoretical FTN capacity gains and practical 6G deployment readiness.

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