Spectrally efficient multiplexing of O-QPSK or VSB signals using wavelet packet-based filter banks

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

“…This paper focuses on the research started by the author in 1995 on using filter bank trees associated with wavelet packet trees to add a significant set of desirable properties to transmultiplexers or, what is equivalent, OFDM type multiband, multicarrier systems. Therefore, it continues and extends the description of the fundamental research results in [1] on the multiplexing of VSB signals using wavelet packet-based filter bank trees for the out-bound transmission of multi-user, spectrally efficient, minimally interfering signals with bandwidth-on-demand capability. The focus in this paper is on the design of modified filters and filter bank trees and using those that provide some improvements, advantages and efficiencies in their designs.…”

“…This also results in fewer delay elements in the design for the filter banks, with a concomitant decrease in the overall signal delay in traversing the filter banks from the input to the transmitter to the output of the receiver. It is noted that this also shows that the filter bank designs, with the same quadrature mirror filter (QMF) pairs replicated throughout the synthesis filter bank at the transmitter, and the matching QMF pairs replicated throughout the analysis filter bank at the receiver, so as to give perfect reconstruction, as used in [1,86] in the conventional wavelet packet filter bank theory, are not the only ones that are associated with wavelet packets, so the previous wavelet packet theory [86] is not complete. The first design in Sect.…”

“…The O-QAM channel magnitude frequency responses are shown to overlap. In [72] Sablatash, Lodge and McGee showed the equivalence between offset digital quadrature phase shift keying (O-QPSK), which is the same as O-QAM and digital VSB, which had been proven in the analogue domain in a Bell Laboratories memorandum or note by Becker cited in [1]. Thus, the world of transmultiplexer design moved on, with the publication of [70,71], from digital SSB designs to those using digital VSB or, equivalently, digital O-QAM or digital O-QPSK, with maximum spectral efficiency.…”

“…5, is the replacement of the wideband VSB filter centred on either the positive or negative frequency axis following a synthesis filter bank tree at the transmitter by a discrete Fourier transform (DFT) polyphase synthesis filter bank [87], and the replacement of the matching wideband VSB filter at the receiver by a DFT polyphase analysis filter bank [88][89][90][91][92][93]. This results in fewer levels of bandwidth on demand [1] but fewer overall delay components and shorter overall signal delay from the input to the transmitter to the output of the receiver, a tradeoff and design flexibility that may be useful in practice. It is shown that the matching receiver design in Fig.…”

“…They were considered to provide the most efficient use of the then available and possible spectrum and used in designs and implementations of transmultiplexers from the early 1970s through to some time in about the mid1980s. Vestigial sideband (VSB) [1] digital transmultiplexers with overlapping but orthogonal magnitude frequency and phase characteristics of the channels were developed starting some about 1983 that achieved maximum spectral efficiency. A VSB analogue transmultiplexer that achieved maximum spectral efficiency was developed by Chang some time before 1966 and described in [2], but it was not until about 1981, with the innovative design of a multicarrier quadrature amplitude modulation (QAM) scheme, and with the advent in about 1983 of perfect reconstruction filter banks (PRFs), that maximum spectral efficiency for orthogonal, overlapping digital channels was achieved.…”