A 1.6 Mbps digital-QAM system for DSL transmission

Daneshrad, Babak; Samueli, H.

doi:10.1109/49.475533

Cited by 22 publications

(11 citation statements)

References 21 publications

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“…By using one FEXT canceller for the FEXT from pair #10, about 6 dB performance improvement (from 27.4 dB to 33.1 dB) has been achieved, with the performance of the receiver then limited by the FEXT from pair #15. Note that the performance improvement of 6 dB corresponds to the FEXT power difference between pair combinations (4, 10) and (4,15). Adding one more FEXT canceller for the FEXT from pair #15 gives further improvement by about 3 dB.…”

Section: Simulation Results and Discussionmentioning

confidence: 99%

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FEXT cancellation for twisted-pair transmission

Kang

Park

2002

IEEE J. Select. Areas Commun.

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This paper discusses a far-end crosstalk (FEXT) canceller for twisted-pair transmission. Many twisted-pair systems such as fiber-to-the-curb, very high-speed digital subscriber line, and high-speed LAN systems, use frequency-division duplexing (FDD) for duplex transmission. It is shown that the maximum reach of FDD twisted-pair system is limited by the performance of its upstream channel, which is assumed to be located at higher frequencies than the downstream channel. In order to improve the performance of such FDD transceiver, FEXT cancellation is introduced for the channel at higher frequencies. A system arrangement and its blind startup procedure are studied when the FEXT canceller and equalizer are jointly adapted to combat channel intersymbol interference, FEXT, and other additive noise. We investigate the initial convergence and the steady-state behavior of the proposed twisted-pair system without requiring transmission of an ideal training sequence. Measured characteristics as well as analytical model of the FEXT channel are used to estimate the time span needed for the FEXT canceller. It is also shown that the memory span for the FEXT canceller is almost independent of the channel, thus making our results useful for the twisted-pair system over all different channels.Index Terms-Blind equalization, Echo/near-end crosstalk/ far-end crosstalk canceller, twisted-pair environment.

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Section: Simulation Results and Discussionmentioning

confidence: 99%

“…The signal at the input of the receiver can be written as (4) where and are a desired complex data symbol and a complex FEXT generating signal, respectively. The symbol represents the real part of .…”

Section: Performance Of Transceiver With Fext Canceler and Equalmentioning

confidence: 99%

FEXT cancellation for twisted-pair transmission

Kang

Park

2002

IEEE J. Select. Areas Commun.

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“…The integration of TCM and precoding is described in detail in [7]. The fundamentals of QAM can be found in [8], while the application of QAM to ADSL is described in [9]. Tomlinson-Harashima Precoding for QAM systems (in a wireless environment) is described in [10], although the author assumes that the channel is reciprocal in nature, an assumption that is not generally possible to make with a DSL system, particularly due to the differences in receiver and transmitter crosstalk environments.…”

Section: Introductionmentioning

confidence: 99%

A time-delayed DFE QAM adaptive precoder

Glavin

Jones

2004

2004 IEEE International Conference on Communications (IEEE Cat. No.04CH37577)

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This paper addresses the issue of equalization of highspeed data-communications systems (e.g. Digital Subscriber Line) under dynamic channel conditions, where the modulation format is Quadrature Amplitude Modulation (QAM). In particular, the focus is on systems that use a combination of Forward Error Correction and Tomlinson-Harashima Precoding to achieve the necessary performance. Previous work by the authors using Pulse Amplitude Modulation (PAM) has shown that such systems operating with a fixed precoder will suffer significant performance degradation in certain cases where the channel changes during run-time. Furthermore, the effects of these channel changes may be minimised using a novel adaptive precoder architecture. This paper extends the previous work to the case of 2-dimensional QAM, and shows that the proposed adaptive precoder algorithm allows the QAM system to rapidly respond to dynamic channel conditions, thus minimising the impact of channel changes on overall system performance.

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“…Blind equalization techniques afford channel equalization without loosing the valuable channel capacity. There are three major basic algorithms for blind equalization: the CMA, the reduced constellation algorithm (RCA), and the multi-modulus algorithm (MMA) [1][2][3][4][5][6] .…”

Section: Introductionmentioning

confidence: 99%

Improving the performance of the error function for fast phase recovery of QAM signals in CMA blind equalizers using variable step

2004

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A new constant modulus algorithm (CMA) type of error function for fast phase recovery of QAM signals was recently proposed in which the cost function of the error function recovers the phase simultaneously with the equalization. In this paper we propose variable step (VS) in the update equations of new error function to enhance the performance of convergence speed and residual inter-symbol interference (ISI). Effectiveness of the error function for well-behaved channel, under-modeled channel and channel disparity are presented. Simulation results are presented to compare the performance of VS, constant step (CS) and the modified CMA (MCMA) using 16-QAM signal constellation.

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A 1.6 Mbps digital-QAM system for DSL transmission

Cited by 22 publications

References 21 publications

FEXT cancellation for twisted-pair transmission

FEXT cancellation for twisted-pair transmission

A time-delayed DFE QAM adaptive precoder

Improving the performance of the error function for fast phase recovery of QAM signals in CMA blind equalizers using variable step

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