Expanded Constellation Mapping for Enhanced Far-End-Cross-Talk Cancellation in G.fast

Zhang, Rong; Rawi, Anas F. Al; Humphrey, Leslie D.; Hanzo, Lajos

doi:10.1109/lcomm.2016.2599514

Cited by 8 publications

(4 citation statements)

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“…With respect to the MUP design for downstream DSL, it is known from (9)(19) and Fig. 4 that the SNR penalty is the dominant problem over the wide bandwidth of G.mgfast (also in [42], [161]) compared to the losses discussed in Sec. III-C3.…”

Section: ) the Essence Of Vectoring And The Dualitymentioning

confidence: 99%

“…Therefore we in general need more expensive circuitry for the DP of G.mgfast using the VP-based approach. As a design alternative of sphere encoding, Zhang et al [161] proposed the expanded constellation mapping scheme that solves the closest point problem of a finite lattice, which is more closely related to the sphere decoding based implementation of MLDs. The sphere decoding algorithm naturally works on a finite lattice, where the candidate lattice points are confined in a pre-determined region.…”

Section: ) Remarksmentioning

confidence: 99%

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Far-End Crosstalk Mitigation for Future Wireline Networks Beyond G.mgfast: A Survey and an Outlook

Zhang

et al. 2020

IEEE Access

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With the escalating demand for high speed, high reliability, low latency, low cost and ubiquitous connectivity, the telecommunications industry is entering a new era where the ultimate optimality of the current wireline-wireless access network has to be achieved. Regarding the current wireline network paradigm, dominated by the copper-based digital subscriber lines (DSL) technology, multi-Gigabit data rate is the ambitious design objective at the customer end for the forthcoming ITU-T G.mgfast standard. In order to prepare for the new challenges in the era of total network convergence, both the wireline and the wireless community must be able to think beyond their respective conventions and learn from each other if necessary. Overall, the current DSL-based wireline network architecture is prone to the mutual interference resulting in far-end crosstalk (FEXT). The newly expanded 424/848 MHz spectrum of the ambitious G.mgfast project introduces far higher FEXT than that over the current 212/30 MHz G.fast/VDSL2 band. Additionally, the coexistence of multiple standards will also cause 'alien' FEXT. In these cases, using the plain zero forcing precoding (ZFP) will no longer attain a sufficiently high performance. However, as shown in the field of wireless communications, using lattice reduction as a signal space remapping technique significantly improves the performance of traditional multiuser detectors (MUD) and of the respective multiuser precoders (MUP). These promising techniques have largely remained unexploited in commercial wireless communications, due to their complexity in the face of the rapidly fluctuating wireless channels. In this survey, we present an overview of the state-of-the-art in wireline access network and an outlook for recent technological advances in the holistic 'wireline + wireless' access network in the context of network convergence, focusing on the dominant challenge of FEXT mitigation in future DSL networks. Against this background, we investigate both the family of linear precoding and of the Tomlinson-Harashima precoding (THP) schemes conceived for classic DSL. Furthermore, we present a tutorial on the family of lattice reduction aided MUPs, as well as quantifying their expected performances in realistic DSL scenarios. As a by-product, we also demonstrate the duality between MUP and MUD, in the hope that the fifty years' history of MUD could be used to accelerate the development of efficient near-optimal MUPs for future DSL. Under the recommended operating conditions of the 212 MHz profile of G.fast, our benchmark comparisons indicate that the lattice reduction aided techniques are very powerful compared to conventional schemes. In particular, their good performances do not rely on optimized spectrum balancing, and they are also shown to be relatively robust against channel state information (CSI) estimation error, under the assumption of perfectly time-invariant DSL channels.

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Section: ) the Essence Of Vectoring And The Dualitymentioning

confidence: 99%

Section: ) Remarksmentioning

confidence: 99%

Far-End Crosstalk Mitigation for Future Wireline Networks Beyond G.mgfast: A Survey and an Outlook

Zhang

et al. 2020

IEEE Access

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“…Hekrdla et al [9] developed a dynamic ordering-based THP by taking into account the specific G.fast channel statistics. Zhang et al [10] conceived the concept of expanded constellation mapping for maximizing the received signal power, while cancelling the FEXT. However, the THP imposes a high computational complexity both on the transmitter and receiver.…”

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Differential Evolution Algorithm Aided Turbo Channel Estimation and Multi-User Detection for G.Fast Systems in the Presence of FEXT

et al. 2018

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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 valuebased 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

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“…This algorithm works on the principle of expanded constellation mapping [3], the transmitted symbol on each tone has to be re-mapped with the best possible symbol among the expanded constellation set. The best possible symbol can be found by optimization.…”

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confidence: 99%

Novel precoding algorithm for VDSL-2

Katiyar¹,

Padmaja²

2017

IJET

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Abstract-We propose a novel concept of symbol relocation for the improvement of received signal power in diagonal precoder. In the past, many precoding algorithm have been proposed, they all suffer either in terms of low bit rate, high complexity and less received signal power. The proposed symbol relocation concept in diagonal precoder gives high data rate with high received signal power. Complexity of the diagonal precoder has been checked using digital signal processor starter kit -6713, a 32 bit floating point digital signal processor. Our results shows that there is improvement in received signal power by 20 dB while maintaining the same bit rate with low complexity of the system. Keywords-VDSL (Very high speed digital subscriber line), Precoder, PSD (Power spectral density), DSL (Digital subscriber line). I. INTRODUCTIONDigital subscriber line is a very old broadband communication technology, which use the potential of exiting twisted pair telephone line. It provide services such as high speed internet access, voice and multimedia communication over conventional telephone line which is already installed for residential and official use to home and in offices. In the present scenario when all the devices are going to connect through internet, there is requirement of high band width. To full fill the requirement of high speed transmission, DSL technology shifted from Asymmetric digital subscriber line (ADSL), Very high speed digital subscriber line (VDSL), VDSL-2 to Fiber to the transmission point (FTTx) and Giga bit fast transmission (G -Fast) with the data rate up to 100 Mbps.VDSL-2 is advance form of VDSL and operate at frequency range of 30 Mhz. Advance version of xDSL is G-fast, which work at the frequency range of 100 Mhz. At higher frequencies, the problem due to electromagnetic coupling between twisted pair wire will also increase. One of the solution to minimize electromagnetic coupling is to decrease the length of wire from 1kilometer (as in ADSL) to 400 meters. Develop new crosstalk minimization algorithm for the improvement in data rate. Crosstalk is classified in two types, Near end crosstalk (NEXT) and Far end crosstalk (FEXT). Effect of crosstalk on wire pair is shown in Fig. 1.

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Expanded Constellation Mapping for Enhanced Far-End-Cross-Talk Cancellation in G.fast

Cited by 8 publications

References 9 publications

Far-End Crosstalk Mitigation for Future Wireline Networks Beyond G.mgfast: A Survey and an Outlook

Far-End Crosstalk Mitigation for Future Wireline Networks Beyond G.mgfast: A Survey and an Outlook

Differential Evolution Algorithm Aided Turbo Channel Estimation and Multi-User Detection for G.Fast Systems in the Presence of FEXT

Novel precoding algorithm for VDSL-2

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