Very-high-speed digital subscriber lines

Cioffi, J.M.; Oksman, Vladimir; Werner, Jean-Jacques; Pollet, T.; Spruyt, P.; Chow, J.S.; Jacobsen, K.S.

doi:10.1109/35.755453

Cited by 53 publications

(29 citation statements)

References 3 publications

(4 reference statements)

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“…The VDSL signals occupy a 300 KHz-30 MHz band within the bandwidth of the twisted pair. The detailed architecture of a VDSL system is discussed in [7][8][9][10]. There are essentially two modulation schemes that can be used in VDSL systems, the carrierless AM/PM (CAP) or quadrature amplitude modulation (QAM), and the discrete multi-tone (DMT) modulation .…”

Section: Line Impairments and Impact Of Coding In Vdsl Systemsmentioning

confidence: 99%

“…The advantages of using QAM for a VDSL include small power consumption, low complexity [20] and flexibility in bandwidth management. The dominant sources of line impairments in a VDSL environment include the far-end crosstalk (FEXT) from other VDSL services, the near-end crosstalk (NEXT) from the baseband services in the same wire bundle, the additive white Gaussian noise (AWGN), the radio frequency interference (RFI) between the VDSL transceivers and the traditional radio receivers and the impulse noise [1,6,7]. The effect of NEXT can be eliminated by employing the FDM approach, in which one directional transmission is adopted among all the telephone subscriber loops.…”

Section: Line Impairments and Impact Of Coding In Vdsl Systemsmentioning

confidence: 99%

“…Hence, in order to study the performance of the BICM scheme, interleaver sizes of 2048, 4096 and 8192 are considered. The turbo code has a rate of 1/2 with a generator polynomial (7,5). Figures 6, 9 and 10 show the performance of the BICM scheme for interleaver sizes 2048, 4096 and 8192, respectively.…”

Section: Effect Of Interleaver Sizementioning

confidence: 99%

“…From Table 8, we can observe that the BICM scheme provides the targeted BER at an SNR of 13.4 dB, Fig. 9 Performance of BICM with encoder generator (7,5), N = 4096…”

Section: Effect Of Interleaver Sizementioning

confidence: 99%

“…Performance of BICM with encoder generator (7,5), N = 8192 12.7 dB and 12.5 dB for interleaver sizes 2048, 4096 and 8192, respectively. The coding gain provided by increasing the interleaver size from 2048 to 4096 is 0.7 dB, and the gain provided by increasing the interleaver size from 4096 to 8192 is 0.2 dB.…”

Section: Fig 10mentioning

confidence: 99%

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A Bandwidth Efficient Turbo Coding Scheme for VDSL Systems

Marti

Ahmad

2008

Circuits Syst Signal Process

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The current forward error correction (FEC) scheme for very high bit-rate digital subscriber line (VDSL) systems in the ANSI standard employs a 16-state fourdimensional (4D) Wei code as the inner code and the Reed-Solomon (RS) code as the outer code. The major drawback of this scheme is that further improvement cannot be achieved without a substantial increase in the complexity and power penalty. Also, a VDSL system employing the 4D Wei-RS scheme operates far below the channel capacity. In 1993, powerful turbo codes were introduced whose performance closely approaches the Shannon limit. In this paper, we propose a bandwidth and power efficient turbo coding scheme for VDSL modems in order to obtain high data rates, extended loop reach and increased transmission robustness. We also propose a pipelined decoding scheme to reduce the latency at the receiver end. The objective of the proposed scheme is to provide a higher coding gain than that given by the 4D Wei-RS scheme, resulting in an improved performance of the VDSL modems in terms of bit rate, loop length and transmitting power. The scheme is investigated for various values of transmitting power, signaling frequencies and numbers of crosstalkers for a targeted bit error rate of 10 −5 and is implemented in a system with a quadrature amplitude modulation in which a mixed set partitioning mapping is employed to reduce the decoding complexity. The effects of code complexity, interleaver length, the number of decoding iterations and the level of modulation on the performance of VDSL modems are explored. Simulation results are presented and compared to those of the 4D Wei-RS scheme. The results show that the choice of turbo codes not only provides a significant coding gain over the standard FEC scheme but also efficiently maximizes the loop length and bit rate at a very low transmitting power in the presence of dominant far-end crosstalk and intersymbol interference. In order to compare the hardware complexity, we synthesize the proposed and 4D Wei-RS schemes using 564 Circuits Syst Signal Process (2008) 27: 563-597 SYNOPSYS with the target technology of Xilinx 4020e-3. The Xilinx field programmable gate array statistics of the proposed scheme is compared with that of the 4D Wei-RS scheme.

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Section: Line Impairments and Impact Of Coding In Vdsl Systemsmentioning

confidence: 99%

Section: Line Impairments and Impact Of Coding In Vdsl Systemsmentioning

confidence: 99%

Section: Effect Of Interleaver Sizementioning

confidence: 99%

“…From Table 8, we can observe that the BICM scheme provides the targeted BER at an SNR of 13.4 dB, Fig. 9 Performance of BICM with encoder generator (7,5), N = 4096…”

Section: Effect Of Interleaver Sizementioning

confidence: 99%

Section: Fig 10mentioning

confidence: 99%

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A Bandwidth Efficient Turbo Coding Scheme for VDSL Systems

Marti

Ahmad

2008

Circuits Syst Signal Process

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DMT Modulation

Schur¹,

Pfletschinger²,

Speidel³

2003

Wiley Encyclopedia of Telecommunications

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Due to the enormous growth of telecommunication services during the last decade, the need for a modulation technique that can transmit reliably high data rates with high band‐width efficiency arises. In this context, multicarrier modulation schemes have become very popular for wireless, mobile as well as fixed networks. A well known applications is digital subscriber line (DSL) communication over wired media using the discrete multitone (DMT) modulation scheme. In this article we present the principles of DMT modulation. We start from the basics of analogue and digital transmission and consecutively develop the main concepts of DMT, as there are: the incorporation of the discrete Fourier transform (DFT) into the modulation scheme, the use of the guard interval to combat interference, the principle of the generalized Nyquist theorem for perfect reconstruction of the signal, the cost‐effective equalization and the adaptive bit‐loading scheme.

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Introduction

Engels¹

Wireless OFDM Systems

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Very-high-speed digital subscriber lines

Cited by 53 publications

References 3 publications

A Bandwidth Efficient Turbo Coding Scheme for VDSL Systems

A Bandwidth Efficient Turbo Coding Scheme for VDSL Systems

DMT Modulation

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