Bit Loading for Precoded DSL Systems

Filho, Danilo Zanatta; Lopes, Renato da Rocha; Ferrari, Rafael; Suyama, Ricardo; Dortschy, Boris

doi:10.1109/icassp.2007.366545

Cited by 6 publications

(4 citation statements)

References 5 publications

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“…, K of the same tone t. Therefore, we will mainly consider centralized DSB algorithms. Furthermore, due both to the non-convexity of VMR computation (which is required for per pair TxPSD and per pair ATP characterization) and to the paucity of literature for joint LRMUP-DSB, we shall use the greedy heuristic bit loading algorithm based on [223], [235] as an extension of the provably optimal singlepair case of [236] for fairly assessing the performances of the vectoring schemes. At the time of writing, we have not found successful application of the duality principle of [226], [227] to overcome the non-convexity associated with lattice reduction.…”

Section: B Spectrum Balancing Algorithms 1) Historical Notementioning

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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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: B Spectrum Balancing Algorithms 1) Historical Notementioning

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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“…, N 2 ), than to place a third bit on the subcarrier corresponding to β 1 . This yields E max tot (2i) = 2γ thr (1) i n=1 1 β n (10) for i = 1, . .…”

Section: Appendixes Appendix a Information Bitrates For Small Atpmentioning

confidence: 99%

“…However, the computational complexity of these Lagrange dual-based algorithms scales badly with an increasing number of users. On the other hand, the computational complexity of the multi-user extension of the greedy bit adding (subtracting) algorithms does scale well with an increasing number of users [9], [10]. This low computational cost however comes at the expense of optimality, as greedy multiuser RA algorithms cannot guarantee a globally optimal solution.…”

Section: Introductionmentioning

confidence: 99%

Modified SNR Gap Approximation for Resource Allocation in LDPC-Coded Multicarrier Systems

et al. 2020

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The signal-to-noise ratio (SNR) gap approximation provides a closed-form expression for the SNR required for a coded modulation system to achieve a given target error performance for a given constellation size. This approximation has been widely used for resource allocation in the context of trellis-coded multicarrier systems (e.g., for digital subscriber line communication). In this contribution, we show that the SNR gap approximation does not accurately model the relation between constellation size and required SNR in low-density parity-check (LDPC) coded multicarrier systems. We solve this problem by using a simple modification of the SNR gap approximation instead, which fully retains the analytical convenience of the former approximation. The performance advantage resulting from the proposed modification is illustrated for single-user digital subscriber line transmission.

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“…Para resolver o problema, nesta seção vamos propor um algoritmo de bitloading discreto baseado em uma heurística gananciosa de otimização, inspirado no algoritmo de bit-filling para maximização de taxa discutido no capítulo anterior, na página 48 (Filho, Lopes, Ferrari, Suyama, & Dortschy, 2007). Nossa proposta se baseia na alocação incremental e, por isso, ela requer a comparação dos custos da alocação de um bit nos diferentes subcanais e pares.…”

Section: Bitloading Discreto Para Sistemas Com Precoderunclassified

Equalização preditiva e otimização de sistemas DSL por gerenciamento espectral e processamento MIMO

Ferrari¹,

Romano²

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Bit Loading for Precoded DSL Systems

Cited by 6 publications

References 5 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

Modified SNR Gap Approximation for Resource Allocation in LDPC-Coded Multicarrier Systems

Equalização preditiva e otimização de sistemas DSL por gerenciamento espectral e processamento MIMO

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