An Energy Efficient QAM Modulation with Multidimensional Signal Constellation

Packing constellations points in higher dimensions, the concept of multidimensional modulation exploits the idea drawn from geometry for searching dense sphere packings in a given dimension, utilising it to minimise the average energy of the underlying constellations. The following work analyses the impactof spherical shaping of the constellations bound instead of the traditional, hyper-cubical bound. Balanced constellation schemes are obtained with the N -dimensional simplex merging algorithm. The performance of constellations of dimensions 2, 4 and 6 is compared to the performance of QAM modulations of equivalent throughputs in the sense of bits transmitted per complex (two- dimensional) symbols. The considered constellations give an approximately 0.7 dB to 1 dB gain in terms of BER over a standard QAM modulation

Construction of signal sets from quotient rings of the quaternion orders associated with arithmetic fuchsian groups

This paper aims to construct signal sets from quotient rings of the quaternion over a real number field associated with the arithmetic Fuchsian group Γ 4g , where g is the genus of the associated surface. These Fuchsian groups consist of the edge-pairing isometries of the regular hyperbolic polygons (fundamental region) P 4g , which tessellate the hyperbolic plane D 2 . The corresponding tessellations are the self-dual tessellations {4g, 4g}. Knowing the generators of the quaternion orders which realize the edge-pairings of the polygons, the signal points of the signal sets derived from the quotient rings of the quaternion orders are determined. It is shown by examples the relevance of adequately selecting the ideal in the maximal order to construct the signal sets satisfying the property of geometrical uniformity. The labeling of such signals is realized by using the mapping by set partitioning concept to solve the corresponding Diophantine equations (extreme quadratic forms). Trellis coded modulation and multilevel codes whose signal sets are derived from quotient rings of quaternion orders are considered possible applications8196050196061CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP305656/2015-52013/25977-

A variable-rate modulation and coding scheme for low earth orbit satellites

Low Earth Orbit (LEO) satellites are increasingly being used for a wide variety of communications applications. These satellites have to operate in widely varying channel conditions. These conditions are often significantly better than the 'worst case' situations that are experienced and thus a single rate transmission scheme is clearly suboptimal. The objective of the thesis is to suggest and test a method of modulation/coding that can take advantage of better signal strength conditions in order to improve data transmission rates. In order to provide the goal of approximately 50kbps transmission in a 10kHz Frequency Division Multiple Access (FDMA) channel it was necessary to consider spectrally efficient, rather than power efficient, modulations. The proposed modulation scheme makes use of an eight-dimensional trellis coded modulation system. Multiple signal constellation sets are used in conjunction with this coding in order to provide different transmission rates, depending on the signal to noise ratio and the channel state. To enhance the suitability of the modulation scheme for the channel, it was combined with Reed-Solomon Coding and interleaving in an inner/outer code arrangement. Various means of determining when to switch between coding rates were discussed briefly, but an in-depth treatment of the subject fell outside of the scope of the thesis. Various combinations of these codes were tested in gaussian noise conditions and various degrees of Rician and Rayleigh fading. In order to make use of the higher rate QAM constellations, it was necessary to provide the decoder with channel state information. The tested system achieved its purpose of providing a variable rate coding scheme resulting in good performance over a range of channel conditions. It is fairly flexible and can be adapted to specific channel requirements

Design and Software Validation of Coded Communication Schemes using Multidimensional Signal Sets without Constellation Expansion Penalty in Band-Limited Gaussian and Fading Channels

It has been well reported that the use of multidimensional constellation signals can help to reduce the bit error rate in Additive Gaussian channels by using the hyperspace geometry more efficiently. Similarly, in fading channels, dimensionality provides an inherent signal space diversity (distinct components between two constellations points), so the amplitude degradation of the signal are combated significantly better. Moreover, the set of n-dimensional signals also provides great compatibility with various Trellis Coded modulation schemes: N-dimensional signaling joined with a convolutional encoder uses fewer redundant bits for each 2D signaling interval, and increases intra-subset minimum squared Euclidean distance (MSED) to approach the ultimate capacity limit predicted by Shannon\u27s theory. The multidimensional signals perform better for the same complexity than two-dimensional schemes. The inherent constellation expansion penalty factor paid for using classical mapping structures can be decreased by enlarging the constellation\u27s dimension. In this thesis, a multidimensional signal set construction paradigm that completely avoids the constellation expansion penalty is used in Band-limited channels and in fading channels. As such, theoretical work on performance analysis and computer simulations for Quadrature-Quadrature Phase Shift Keying (Q2PSK), Constant Envelope (CE) Q2PSK, and trellis-coded 16D CEQ2PSK in ideal band-limited channels of various bandwidths is presented along with a novel discussion on visualization techniques for 4D Quadrature-Quadrature Phase Shift Keying (Q2PSK), Saha\u27s Constant Envelope (CE) Q2PSK, and Cartwright\u27s CEQ2PSK in ideal band-limited channels. Furthermore, a metric designed to be used in fading channels, with Hamming Distance (HD) as a primary concern and Euclidean distance (ED) as secondary is also introduced. Simulation results show that the 16D TCM CEQ2PSK system performs well in channels with AWGN and fading, even with the simplest convolutional encoder tested; achievable coding gains using 16-D CEQ2PSK Expanded TCM schemes under various conditions are finally reported

Geometrically uniform subspace codes and a proposal to construct quantum networks

Orientador: Reginaldo Palazzo JuniorTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de ComputaçãoResumo: Códigos de subespaço se mostram muito úteis contra a propagação de erros em uma rede linear multicast. Em particular, a família dos códigos de órbita apresenta uma estrutura algébrica bem definida o que, possivelmente, resultará na construção de bons algoritmos de decodificação e uma forma sistemática para o cálculo dos parâmetros do código. Neste trabalho, apresentamos um estudo dos códigos de órbita vistos como códigos geometricamente uniformes. A caracterização destas duas classes segue direto da definição de códigos de órbita e, dado um particionamento geometricamente uniforme destes códigos a partir de subgrupos normais do grupo gerador, propomos uma redução sobre o número de cálculos necessários para a obtenção das distâncias mínimas de um código de órbita abeliano e de um código L-nível, além de um algoritmo de decodificação baseado nas regiões de Voronoi. No último capítulo deste trabalho, propomos uma ideia de como projetar, do ponto de vista teórico, uma possível rede capaz de transmitir e operar informações quânticas. Tais informações são representadas por estados quânticos emaranhados, onde cada ket destes estados está associado a um subespaço vetorialAbstract: Subspace codes have been very useful to solve the error propagation in a multicast linear network. In particular, the orbit codes family presents a well-defined algebraic structure, which it will probably provide constructions of good decoding algorithms and a systematic way to compute the parameters of the code. In this work, we present a study of orbit codes seen as geometrically uniform codes. The characterization of both classes is direct from the definition of orbit codes and, given a uniform geometrically partition of these orbit codes from their normal subgroups of the generator group, we propose a reduction of the computation necessary for obtaining the minimum distances of an abelian orbit code and an L-level code, in addition to a decoding algorithm based on Voronoi regions. In the last chapter, we propose a hypothetical quantum network coding for the transmission of quantum information. This network consists of maximum entangled pure quantum states such that each ket of these states is associated with a vector subspaceDoutoradoTelecomunicações e TelemáticaDoutor em Engenharia Elétrica142094/2013-7CAPESCNP