2,067 research outputs found
High speed hardware development for FDMA/TDM system
The development of a transmultiplexor and a quadrature phase shift keying (QPSK) demodulator is discussed. The system is designed to meet real time signal processing requirements of future satellite systems and should consume very little power. The architectures of the transmultiplexor and the demodulator are designed for the pipelining of all the modules, namely the commutator, the filter bank fast fourier transform (FFT), and the internal modules of the QPSK. The architecture is designed for the case of 800 channels. Each channel is to have a bandwidth of 45 KHz and a bit rate of 64 Kb/s. In this case each module will have 22.22 micro seconds to complete a computation
A reconfigurable multicarrier demodulator architecture
An architecture based on parallel and pipline design approaches has been developed for the Frequency Division Multiple Access/Time Domain Multiplexed (FDMA/TDM) conversion system. The architecture has two main modules namely the transmultiplexer and the demodulator. The transmultiplexer has two pipelined modules. These are the shared multiplexed polyphase filter and the Fast Fourier Transform (FFT). The demodulator consists of carrier, clock, and data recovery modules which are interactive. Progress on the design of the MultiCarrier Demodulator (MCD) using commercially available chips and Application Specific Integrated Circuits (ASIC) and simulation studies using Viewlogic software will be presented at the conference
Scalable and Energy-Efficient Millimeter Massive MIMO Architectures: Reflect-Array and Transmit-Array Antennas
Hybrid analog-digital architectures are considered as promising candidates
for implementing millimeter wave (mmWave) massive multiple-input
multiple-output (MIMO) systems since they enable a considerable reduction of
the required number of costly radio frequency (RF) chains by moving some of the
signal processing operations into the analog domain. However, the analog feed
network, comprising RF dividers, combiners, phase shifters, and line
connections, of hybrid MIMO architectures is not scalable due to its
prohibitively high power consumption for large numbers of transmit antennas.
Motivated by this limitation, in this paper, we study novel massive MIMO
architectures, namely reflect-array (RA) and transmit-array (TA) antennas. We
show that the precoders for RA and TA antennas have to meet different
constraints compared to those for conventional MIMO architectures. Taking these
constraints into account and exploiting the sparsity of mmWave channels, we
design an efficient precoder for RA and TA antennas based on the orthogonal
matching pursuit algorithm. Furthermore, in order to fairly compare the
performance of RA and TA antennas with conventional fully-digital and hybrid
MIMO architectures, we develop a unified power consumption model. Our
simulation results show that unlike conventional MIMO architectures, RA and TA
antennas are highly energy efficient and fully scalable in terms of the number
of transmit antennas.Comment: submitted to IEEE ICC 201
Emergence of world-stock-market network
In the age of globalization, it is natural that the stock market of each
country is not independent form the other markets. In this case, collective
behavior could be emerged form their dependency together. This article studies
the collective behavior of a set of forty influential markets in the world
economy with the aim of exploring a global financial structure that could be
called world-stock-market network. Towards this end, we analyze the
cross-correlation matrix of the indices of these forty markets using Random
Matrix Theory (RMT). We find the degree of collective behavior among the
markets and the share of each market in their structural formation. This
finding together with the results obtained from the same calculation on four
stock markets reinforce the idea of a world financial market. Finally, we draw
the dendrogram of the cross-correlation matrix to make communities in this
abstract global market visible. The dendrogram, drawn by at least thirty
percent of correlation, shows that the world financial market comprises three
communities each of which includes stock markets with geographical proximity
Simultaneous Inference of User Representations and Trust
Inferring trust relations between social media users is critical for a number
of applications wherein users seek credible information. The fact that
available trust relations are scarce and skewed makes trust prediction a
challenging task. To the best of our knowledge, this is the first work on
exploring representation learning for trust prediction. We propose an approach
that uses only a small amount of binary user-user trust relations to
simultaneously learn user embeddings and a model to predict trust between user
pairs. We empirically demonstrate that for trust prediction, our approach
outperforms classifier-based approaches which use state-of-the-art
representation learning methods like DeepWalk and LINE as features. We also
conduct experiments which use embeddings pre-trained with DeepWalk and LINE
each as an input to our model, resulting in further performance improvement.
Experiments with a dataset of 356K user pairs show that the proposed
method can obtain an high F-score of 92.65%.Comment: To appear in the proceedings of ASONAM'17. Please cite that versio
Spin waves interference from rising and falling edges of electrical pulses
The authors have investigated the effect of the electrical pulse width of
input excitations on the generated spin waves in a NiFe strip using pulse
inductive time domain measurements. The authors have shown that the spin waves
resulting from the rising- and the falling-edges of input excitation pulses
interfere either constructively or destructively, and have provided conditions
for obtaining spin wave packets with maximum intensity at different bias
conditions
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