High bit rate digital subscriber lines: a review of HDSL progress

2000

Abstract-Recently, discrete Fourier transform (DFT)-based discrete multitone modulation (DMT) systems have been widely applied to various applications. In this paper, we study a broader class of DMT systems using more general unitary matrices instead of DFT matrices. For this class, we will show how to design the optimal DMT systems over frequency-selective channels with colored noise. In addition, asymptotical performance of DFT-based and optimal DMT systems will be studied and shown to be equivalent. However, for a moderate number of bands, the optimal DMT system offers significant gain over the DFT-based DMT system, as will be demonstrated by examples.

Section: Introductionmentioning

confidence: 99%

Perfect discrete multitone modulation with optimal transceivers

2000

“…The transfer matrix of the overall system can be expressed as (8) The overall system is free from interband ISI if is a diagonal matrix. It is free from intraband ISI when the diagonal elements of are merely delays.…”

Section: Polyphase Representation Of Filterbank Transceiversmentioning

confidence: 99%

“…In many applications [8], [9], [13], the interpolation ratio is chosen to be larger than the order of . In this case, the polyphases of are constants, and the last polyphases are zero.…”

Section: )mentioning

confidence: 99%

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Minimum redundancy for ISI free FIR filterbank transceivers

2002

Abstract-There has been great interest in the design of filterbank transceivers. Usually, with proper time domain equalization, the channel is modeled as an FIR filter. It is known that for FIR channels, the introduction of certain redundancy allows the receiver to cancel intersymbol interference (ISI) completely, and channel equalization is performed implicitly using FIR transceivers. This scheme allows us to trade bandwidth for ISI cancellation. In this paper, we will derive the minimum redundancy required for the existence of FIR transceivers for a given channel. We will see that the minimum redundancy is directly related to the zeros of the channel and to the Smith form of an appropriately defined channel matrix.

“…ISCRETE multitone modulation (DMT) is now a widely used technique for high-speed transmission over channels such as digital subscriber loops [1]- [5]. In the DMT scheme, the channel is divided into subbands, each with a different frequency band.…”

mentioning

confidence: 99%

ISI-free FIR filterbank transceivers for frequency-selective channels

2001

Abstract-Discrete multitone modulation transceivers (DMTs) have been shown to be very useful for data transmission over frequency selective channels. The DMT scheme is realized by a transceiver that divides the channel into subbands. The efficiency of the scheme depends on the frequency selectivity of the transmitting and receiving filters. The receiving filters with good stopband attenuation are also desired for combating narrowband noise. The filterbank transceiver or discrete wavelet multitone (DWMT) system has been proposed as an implementation of the DMT transceiver that has better frequency band separation, but usually, inrtersymbol interference (ISI) cannot be completely canceled in these filterbank transceivers, and additional equalization is required. In this paper, we show how to use over interpolated filterbanks to design ISI-free FIR transceivers. A finite impulse response (FIR) transceiver with good frequency selectivity can be designed, as will be demonstrated by design examples.