Bandwidth Efficient Transmultiplexers, Part 2: Subband Complements and Performance Aspects

Abstract-This paper examines the performance issues relating to the quadrature amplitude modulation (QAM) and vestigial sideband (VSB) transmultiplexers synthesized in [l]. First, an analysis of the limitations of the configured systems regarding intersymbol interference and crosstalk suppression arising from the use of practical filters is made. Based on these observations, a new design technique for an FIR low-pass prototype that takes the practical degradations into account is formulated. The procedure involves the unconstrained optimization of an error function. A performance evaluation reveals that for four of the five systems, the new method is superior to a minimax approach in that lower intersymbol interference and crosstalk distortions are achieved with a smaller number of filter taps. For the other transmultiplexer, the advantage of the optimized design over the minimax design is in the added flexibility of taking crosstalk into account thereby diminishing the crosstalk distortion. The five transmultiplexers can be converted into new subband systems. We show how the optimized design approach formulated for the transmultiplexers carries over to the new subband systems. I

Фітоценологічна типологія букових лісів Карпатського біосферного заповідника

Carpathian Biosphere Reserve is located in the Transcarpathian region on the south-western macro-slope of the Ukrainian Carpathians. Beech forests on the territory of Carpathian Biosphere Reserve are represented by 16 subformations and 124 associations. The construction of a generalized typological scheme of beech forests of Carpathian Biosphere Reserve on the basis of a dominance classification was carried out by means of graphical visualization of the results of indirect ordination in relation to the distribution of 33 species-dominants of herbal coverage in the context of 16 subformations. The evaluation of complex environmental gradients that determine the structure and direction of variation of forest vegetation was performed on the basis of Detrended Correspondence Analysis (DCA). To interpret the axes of ordination, the correlation of species coordinates with their environmental parameters on Ellenberg's ecological scales was determined. Organizing phytocoenological data on the basis of Detrended Correspondence Analysis allows executing a geometric interpretation of phytocoenological data and presents a dominance classification in the form of a typological scheme. The phytocoenological typological scheme of beech forests of Carpathian Biosphere Reserve can be represented as a hexagon, in the centre of which there is the subformation of Fageta (sylvaticae), and in the corners are as follows: 1) Carpineto (betuli)-Fageta (sylvaticae), Fraxineto (excelsioris)-Fageta (sylvaticae) 2) Abieto (albae)-Piceeto (abietis)-Fageta (sylvaticae), Piceeto (abietis)-Abieto (albae)-Fageta (sylvaticae) 3) Piceeto (abietis)-Fageta (sylvaticae) 4) Sorbeto (aucupariae)-Fageta (sylvaticae) 5) Querceto (petraeae)-Fageta (sylvaticae) 6) Fraxineto (excelsioris)-Ulmeto (glabrae)-Fageta (sylvaticae), Querceto (roboris)-Fageta (sylvaticae). In a three-dimensional space, the typological scheme has the form of a hexagonal pyramid, on the top of which there are the subformations Acereto (pseudoplatani)-Fraxineto (excelsioris)-Fageta (sylvaticae) and Ulmeto (glabrae)-Fageta (sylvaticae).Конструювання фітоценологічної типологічної схеми букових лісів Карпатського біосферного заповідника на основі домінантної класифікації здійснено способом графічної візуалізації результатів непрямої ординації щодо розподілу 33 видів-домінантів трав'яного покриву в розрізі 16 субформацій. Оцінку комплексних градієнтів середовища, які визначають структуру і напрямок варіювання лісової рослинності, виконано на основі аналізу відповідностей із видаленим трендом (DCA, Detrended Correspondence Analysis). Для інтерпретації осей ординації визначено кореляцію координат видів з їх екологічними параметрами за екологічними шкалами Г. Елленберга. Фітоценологічну типологічну схему букових лісів Карпатського біосферного заповідника можна представити у вигляді шестикутника, у центрі якого розташована субформація Fageta (sylvaticae), а в кутах: 1) Carpineto (betuli)-Fageta (sylvaticae), Fraxineto (excelsioris)-Fageta (sylvaticae); 2) Abieto (albae)-Piceeto (abietis)-Fageta (sylvaticae), Piceeto (abietis)-Abieto (albae)-Fageta (sylvaticae); 3) Piceeto (abietis)-Fageta (sylvaticae); 4) Sorbeto (aucupariae)-Fageta (sylvaticae); 5) Querceto (petraeae)-Fageta (sylvaticae); 6) Fraxineto (excelsioris)-Ulmeto (glabrae)-Fageta (sylvaticae), Querceto (roboris)-Fageta (sylvaticae). У тривимірному просторі типологічна схема має вигляд шестикутної піраміди, на вершині якої розташовані субформації Acereto (pseudoplatani)-Fraxineto (excelsioris)-Fageta (sylvaticae) і Ulmeto (glabrae)-Fageta (sylvaticae)

REFERENCES

Abstracl-In this correspondence, we provide simple proofs for th

Lattice-based Nonuniform Vector Quantization

We propose some practical methods for applying a The region 'Rq is denoted as the quantizer shaping region. lattice-based uniform vector quantizer to a nonuniform source. Each Q; has a unique reproduction symbol Oi. W the source The first method, denoted as cluster quantization, is based on using the k-fold cartesian product of a one-dimensional companvectors s E Q; are quantized to d;. This is called a k-dimensional vector quantizer (VQ). der in conjunction with a lattice quantizer. This scheme has an asymptotic gain of 1.53 dB with respect to the optimum onedimensional quantizer. The complexity is essentially the complexity of decoding of a lattice. The second method, denoted as quantizer shaping, is based on selecting an appropriate boundary The objective in the design of a VQ is to minimize the average distortion, namely, for a lattice quantizer. By increasing the space dimensionality, this scheme becomes asymptotically optimum. As a practica