TDM/FDM translation as an application of digital signal processing

Freeny, S. L.

doi:10.1109/mcom.1980.1090173

Cited by 19 publications

(3 citation statements)

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“…With the publication of [6], and the use of polyphase networks [11], what might be called the classic age, starting in about 1968 and continuing through about 1982 and probably dying out a year or so later, of digital transmultiplexers using single sideband channels emerged, and many improvements and modifications in designs and implementations thereof were explored [7][8][9][10][12][13][14][15][16][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][65][66][67], with significant numbers of these resulting in commercial equipment. Some novel ideas such as the use of wave digital filters [40][41][42][43][44]62,63], directional filters [64] and spread spectrum modulation were also explored and implemented [63].…”

Section: Concluding Discussionmentioning

confidence: 99%

Designs and architectures of filter bank trees for spectrally efficient multi-user communications: review, modifications and extensions of wavelet packet filter bank trees

Sablatash¹

2007

SIViP

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A review is presented first of the evolution of transmultiplexers since about 1966, in the context of a long progression of theoretical advances and developments leading to recent proposals to fundamentally improve OFDM type systems using principles of perfect reconstruction filter (PRF) banks. The equivalence of transmultiplexers to OFDM type multi-user systems is discussed. The desirable goals for performance and implementation of transmultiplexers or multiband, multiuser communication systems that are addressed and met in this paper using filter bank trees are set down. Then modifications and extensions are presented of the designs and architectures of wavelet packet based synthesis and analysis pairs of filter bank trees (Sablatash and Lodge in Digital Signal Process 13: 58-92, 2003) that can be used as transmultiplexers. These exhibit a number of advantages over the previous designs and address three shortcomings of the designs used to illustrate basic principles in Sablatash and Lodge (Digital Signal Process 13:58-92, 2003). The first of these is the asymmetry of the magnitude frequency responses of the multiplexer channels, which is addressed using a symmetric design for a lowpass and highpass quadrature mirror filter (QMF) pair described herein. The second is the problem of minimizing the total delay of the signal in passing through the analysis and synthesis filter banks. This is addressed using an architecture involving DFT polyphase synthesis filter banks to replace the wideband VSB filters at the roots of the two identical synthesis filter bank trees, but results in the multiplexer having fewer levels. In this way a Financial support under Industry Canada's Spectrum Research Funding is gratefully acknowledged.M. Sablatash (tradeoff is effected of lower delay and complexity with fewer levels of bandwidth on demand. At the receiver matching DFT polyphase analysis filters and the other matching analysis filters are implemented. The third shortcoming is the difficulty in designing a synchronization scheme if the filters in the synthesis and analysis filter banks have non-linear phase. This is addressed by designing linear phase filters that do not affect the ISI to any significant degree for communication purposes, although exact perfect reconstruction is lost, but greatly ease and improve the design of the synchronization scheme. Relationships of this paper and its advantages over recent research studies and IEEE 802.22 standards proposals using PR filter banks for multi-user systems to greatly improve on OFDM systems are discussed.

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Section: Concluding Discussionmentioning

confidence: 99%

Designs and architectures of filter bank trees for spectrally efficient multi-user communications: review, modifications and extensions of wavelet packet filter bank trees

Sablatash¹

2007

SIViP

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“…Now, a simple equivalence follows immediately from (3) and from the fact that the transfer function of the pseudo-Npath digital filters has the form o(H(z N ) (see Fig. the polyphase filter bank principle [34,6,8] or the lattice wave digital filters with bireciprocal characteristic function [9,25,29]. Really, this fact is obvious and wellknown, see e.g.…”

Section: For Every K We Can Define Another Integer N Such Thatmentioning

confidence: 92%

“…To connect the different parts sampling rate conversion (increase or decrease) is necessary. transmultiplexers [1,[6][7][8] the attenuation specifications will be alleviated by preceding filtering steps [9][10][11]. Often, in larger multirate digital systems as e.g.…”

Section: Introductionmentioning

confidence: 99%