Abstract
The ever-increasing demand for broadband Internet access has motivated the further development of the digital subscriber line to the G.fast standard in order to expand its operational band from 106 MHz to 212 MHz. Conventional far-end crosstalk (FEXT) based cancellers falter in the upstream transmission of this emerging G.fast system. In this paper, we propose a novel differential evolution algorithm (DEA) aided turbo channel estimation (CE) and multi-user detection (MUD) scheme for the G.fast upstream including the frequency band up to 212 MHz, which is capable of approaching the optimal Cramer-Rao lower bound of the channel estimate, whilst approaching the optimal maximum likelihood (ML) MUD's performance associated with perfect channel state information, and yet only imposing about 5% of its computational complexity. Explicitly, the turbo concept is exploited by iteratively exchanging information between the continuous value-based DEA assisted channel estimator and the discrete value-based DEA MUD. Our extensive simulations show that 18 dB normalized mean square error gain is attained by the channel estimator and 10 dB signal-to-noise ratio gain can be achieved by the MUD upon exploiting this iteration gain. We also quantify the influence of the CE error, of the copper length and of the impulse noise. Our study demonstrates that the proposed DEA aided turbo CE and MUD scheme is capable of offering near-capacity performance at an affordable complexity for the emerging G.fast systems.
Highlights
The demand for high-speed broadband Internet access has motivated the construction of the hybrid digital subscriber line (DSL) and optical fiber infrastructure, which has been standardized as G.fast by the International Telecommunication Union Telecommunication Standardization Sector (ITU-T) [1]
We evaluate the performance of the proposed differential evolution algorithm (DEA) assisted turbo channel estimation (CE) and multi-user detection (MUD) for upstream G.fast systems operated in the frequency range of 2 MHz to 212 MHz, which are split into 4096 tones
We have proposed a DEA aided turbo CE and MUD for mitigating the adverse effects of FEXT encountered by the G.Fast systems caused by the utilization of high frequencies up to 212 MHz
Summary
The demand for high-speed broadband Internet access has motivated the construction of the hybrid digital subscriber line (DSL) and optical fiber infrastructure, which has been standardized as G.fast by the International Telecommunication Union Telecommunication Standardization Sector (ITU-T) [1]. The G.fast standard has already exploited a broad spectrum spanning up to 106 MHz, while the band up to 212 MHz has been planed for future broadband access [2, 3]. Exploiting the spectrum beyond 30 MHz inevitably imposes significant electromagnetic coupling between the neighboring twisted-pairs, which is referred to as crosstalk. There are two types of crosstalk, depending on the specific source of coupling. FEXT remains a significant impairment that hampers achieving high data rates for G.fast systems [1]
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