Frequency Domain Echo Canceller for DMT-Based Systems

Lindqvist, Fredrik; Fertner, Antoni

doi:10.1109/lsp.2011.2170679

Cited by 8 publications

(4 citation statements)

References 9 publications

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“…Nevertheless, in the case of LR-VDSL2, besides ISI/ICI, there is an additional issue of echo and nearend crosstalk (NEXT) generation when considering a too short CP. This can be partly solved by echo cancellation techniques [10]- [12]. Moreover, it is emphasized that the main application use-case of the paper is LR-G.fast, in which this issue of NEXT and echo does not appear.…”

Section: Introductionmentioning

confidence: 99%

MIMO Per-Tone Equalizer Design for Long Reach xDSL

Sharma

Verdyck

Lefevre

et al. 2022

IEEE Open J. Commun. Soc.

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Recently, long reach x-digital subscriber line (LR-xDSL) has been proposed to extend the reach of conventional DSL systems. The extended loop lengths are characterized by a longer channel impulse response (CIR), which requires a similarly longer cyclic prefix (CP) to successfully eliminate the inter-symbol interference (ISI) between successive time-domain discrete multi-tone (DMT) symbols and inter-carrier interference (ICI) between the carriers or tones of the same DMT symbol. This adds a large overhead to the transmitted symbols and results in throughput loss. A per-tone equalizer (PTEQ) is an attractive alternative to deal with extended loop lengths. However, it imposes a large initialization computational complexity and memory requirement, hindering the use of a PTEQ in practical multiple-input multiple-output (MIMO) scenarios. To tackle this problem, a specific structure in the MIMO DSL channel, namely that the combined ISI and ICI signal power from the crosstalk channels is significantly lower than the desired and combined ISI and ICI signal power from the direct channels, may be exploited in deriving a novel low complexity/memory solution, here referred as sparse MIMO PTEQ, with negligible impact (≈ 0.5% drop) on performance compared to a full MIMO PTEQ. For a conventional DSL binder size of 16 lines and a PTEQ order of 3, the proposed sparse MIMO PTEQ performs at 42% of the initialization computational complexity and 29.7% of the memory requirement, with negligible performance degradation, compared to a full MIMO PTEQ. The initialization computational complexity and memory requirement is further reduced by the proposed diagonal MIMO PTEQ which operates at 0.4% of the initialization computational complexity of a full MIMO PTEQ and requires 6.25% memory compared to a full MIMO PTEQ, with some degradation in the performance compared to the full MIMO PTEQ. The diagonal MIMO PTEQ has the additional benefit that it can be applied in both upstream and downstream scenarios, in contrast to the full and sparse MIMO PTEQ which can be used only in upstream scenarios.

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Section: Introductionmentioning

confidence: 99%

MIMO Per-Tone Equalizer Design for Long Reach xDSL

Sharma

Verdyck

Lefevre

et al. 2022

IEEE Open J. Commun. Soc.

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“…In [18], the interference cancellation (IC) reduces interference effect, and the overlap ratio could be enhanced while maintaining a high quality of service (QoS). The echo cancellation method has been studied in [19], [20], and analyzed in a deferent domain such as in [21] for voice over IP (VoIP) communication acoustic echo.…”

Section: Introductionmentioning

confidence: 99%

Very High-Performance Echo Canceller for Digital Terrestrial Television in Single Frequency Network

Ar-Reyouchi¹,

Lamrani²,

Ghoumid³

et al. 2020

IJACSA

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The principal aim of this paper is to cancel out the natural and man-made echoes in single-frequency networks (SFN). The challenge is to detect and remove feedback echoes and enhance the intelligibility of the essential parameters in SFN of digital terrestrial television broadcasting (DTTB) transmitter systems, especially the Modulation Error Ratio (MER), with optimizing coverage areas. We suggest a Digital Video Broadcasting (DVB) gap filler (GF) with two types of echo cancelling: Digital Adaptive Equalizer (DAE) and Doppler Enhanced Echo Canceller (DEEC). The proposed GF outperforms standard GF (SGF), finite impulse response filter (FIR GF), and adaptive GF (AGF) techniques by 33%, 17%, and 13%, respectively. Furthermore, the obtained MER makes the proposed GF (PGF) ideal for operating in SFN using Coded Orthogonal Frequency Division Multiplex (COFDM) technique.

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“…Echoes level must be maintained to an allowable threshold to avoid distortions and oscillations . Several techniques exist to reduce echoes, especially in the area of acoustics as linear/nonlinear predictions, Wiener and Volterra filters …”

Section: Introductionmentioning

confidence: 99%

“…22 Several techniques exist to reduce echoes, especially in the area of acoustics as linear/nonlinear predictions, Wiener and Volterra filters. [23][24][25] In global system for mobile communications and terrestrial trunked radio standards, the narrow-band signal (NBS) jumps over a large frequency span. With these signals, adaptive linear filtering such as least mean square (LMS), recursive LMS, and normalized LMS are less effective.…”

Section: Introductionmentioning

confidence: 99%

Detection and measurement of radio frequency feedback for an on‐frequency repeater

Zeher

Bilbault

Binczak

2017

Int J Communication

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International audienceThe radio frequency feedback (RFF) occurs when the insulation is insufficient between the antennas of an on-frequency repeater, increasing digital transmission errors. In addition, a strong RFF could compromise system stability of the on-frequency repeater because of the growing power in the closed-loop. Automatic gain control is widely used by the on-frequency repeater to regulate the power, this solution being generally used with echo cancellation processes. Most of echo cancellation techniques are based on digital processing such as adaptive filters whose the effectiveness and the algorithm speed are depending on the signal frequency, the bandwidth and the closed-loop parameters. This paper describes a solution of RFF estimation and detection regardless of the receiving signal modulation. By using the frequency scanning and the analysis of the power spectral density peaks in the system, this solution is reliable whatever are the values of the gain-margin and the loop-delay. Simulations and experimental implementation using field-programmable gate array validate the solution. In addition, an example of applications is given in the context of the interference cancellation

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Frequency Domain Echo Canceller for DMT-Based Systems

Cited by 8 publications

References 9 publications

MIMO Per-Tone Equalizer Design for Long Reach xDSL

MIMO Per-Tone Equalizer Design for Long Reach xDSL

Very High-Performance Echo Canceller for Digital Terrestrial Television in Single Frequency Network

Detection and measurement of radio frequency feedback for an on‐frequency repeater

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