1,120 research outputs found
Supervised Machine Learning for Signals Having RRC Shaped Pulses
Classification performances of the supervised machine learning techniques
such as support vector machines, neural networks and logistic regression are
compared for modulation recognition purposes. The simple and robust features
are used to distinguish continuous-phase FSK from QAM-PSK signals. Signals
having root-raised-cosine shaped pulses are simulated in extreme noisy
conditions having joint impurities of block fading, lack of symbol and sampling
synchronization, carrier offset, and additive white Gaussian noise. The
features are based on sample mean and sample variance of the imaginary part of
the product of two consecutive complex signal values.Comment: 5 page
Does the Cross-Talk Between Nonlinear Modes Limit the Performance of NFDM Systems?
We show a non-negligible cross-talk between nonlinear modes in Nonlinear
Frequency-Division Multiplexed system when data is modulated over the nonlinear
Fourier spectrum, both the continuous spectrum and the discrete spectrum, and
transmitted over a lumped amplified fiber link. We evaluate the performance
loss if the cross-talks are neglected.Comment: Invited paper, European Conference on Optical Communication (ECOC
2017), Sept. 2017, p. Th.1.D.
Conjugate-Root Offset-QAM for Orthogonal Multicarrier Transmission
Current implementations of OFDM/OQAM are restricted to band-limited symmetric
filters. To circumvent this, non-symmetric conjugate root (CR) filters are
proposed for OQAM modulation. The system is applied to Generalized Frequency
Division Multiplexing (GFDM) and a method for achieving transmit diversity with
OQAM modulation is presented. The proposal reduces implementation complexity
compared to existing works and provides a more regular phase space.
GFDM/CR-OQAM outperforms conventional GFDM in terms of symbol error rate in
fading multipath channels and provides a more localized spectrum compared to
conventional OQAM.Comment: 4pages, revised version submitted to IEEE WC
Notes on analogue and digital amplitude modulation
Notes on AM, DSBSC, QAM, BPSK, 4QAM, 8PSK, 16QA
Constellation Shaping for WDM systems using 256QAM/1024QAM with Probabilistic Optimization
In this paper, probabilistic shaping is numerically and experimentally
investigated for increasing the transmission reach of wavelength division
multiplexed (WDM) optical communication system employing quadrature amplitude
modulation (QAM). An optimized probability mass function (PMF) of the QAM
symbols is first found from a modified Blahut-Arimoto algorithm for the optical
channel. A turbo coded bit interleaved coded modulation system is then applied,
which relies on many-to-one labeling to achieve the desired PMF, thereby
achieving shaping gain. Pilot symbols at rate at most 2% are used for
synchronization and equalization, making it possible to receive input
constellations as large as 1024QAM. The system is evaluated experimentally on a
10 GBaud, 5 channels WDM setup. The maximum system reach is increased w.r.t.
standard 1024QAM by 20% at input data rate of 4.65 bits/symbol and up to 75% at
5.46 bits/symbol. It is shown that rate adaptation does not require changing of
the modulation format. The performance of the proposed 1024QAM shaped system is
validated on all 5 channels of the WDM signal for selected distances and rates.
Finally, it was shown via EXIT charts and BER analysis that iterative
demapping, while generally beneficial to the system, is not a requirement for
achieving the shaping gain.Comment: 10 pages, 12 figures, Journal of Lightwave Technology, 201
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