scholarly journals Some Extended Results on the Design of Punctured Serially Concatenated Convolutional Codes

2017 ◽  
Vol 2 (3) ◽  
pp. 235
Author(s):  
Massimiliano Laddomada ◽  
Bartolo Scanavino
Keyword(s):  
Error Probability ◽  
Selection Criteria ◽  
Convolutional Codes ◽  
Companion Paper ◽  
Design Guidelines ◽  
Effective Algorithm ◽  
Signal To Noise ◽  
Convolutional Encoders ◽  
Simulation Results ◽  
Serially Concatenated

The aim of this paper is twofold. On one hand, it presents the results of the search for good punctured systematicrecursive convolutional encoders suitable for application in serially concatenated convolutional codes (SCCCs) operating in two different target regions: at low-to moderate signal-to-noise ratios (SNRs), i.e., in the so called waterfall region, and at high SNRs. On the other hand, it provides some useful design guidelines for choosing the constituent encoders in an SCCC. The results of the search for good SCCCs operating in the waterfall region rely upon an effective algorithm, based on density evolution technique, first proposed in a companion paper. Good punctured SCCCs were obtained through considerationsdeduced by the behaviour of the bit error probability of an SCCC for high values of both SNR and interleaver length, i.e., through asymptotic considerations. The mother codes in the serial concatenation are rate 1/2 recursive convolutional encoders (RCC) found by an exhaustive search for encoders tailored to SCCC schemes, using two different selection criteria. Extensive tables of optimized puncturing patterns for various mother codes and SCCCs are presented along with sample simulation results.

scholarly journals Cooperative Spectrum Sensing Based on Convolutional Neural Networks

2021 ◽  
Vol 11 (10) ◽  
pp. 4440
Author(s):  
Youheng Tan ◽  
Xiaojun Jing
Keyword(s):  
Neural Networks ◽  
Spectrum Sensing ◽  
Convolutional Neural Networks ◽  
Cooperative Spectrum Sensing ◽  
Signal To Noise Ratio ◽  
Majority Voting ◽  
Signal To Noise ◽  
Hidden Terminal ◽  
Simulation Results ◽  
Sensing Performance

Cooperative spectrum sensing (CSS) is an important topic due to its capacity to solve the issue of the hidden terminal. However, the sensing performance of CSS is still poor, especially in low signal-to-noise ratio (SNR) situations. In this paper, convolutional neural networks (CNN) are considered to extract the features of the observed signal and, as a consequence, improve the sensing performance. More specifically, a novel two-dimensional dataset of the received signal is established and three classical CNN (LeNet, AlexNet and VGG-16)-based CSS schemes are trained and analyzed on the proposed dataset. In addition, sensing performance comparisons are made between the proposed CNN-based CSS schemes and the AND, OR, majority voting-based CSS schemes. The simulation results state that the sensing accuracy of the proposed schemes is greatly improved and the network depth helps with this.

An Improved Acquisition Method for High-Order BOC-Modulated Signals Based on Fractal Geometry

2013 ◽  
Vol 846-847 ◽  
pp. 1185-1188 ◽  
Author(s):  
Hua Bing Wu ◽  
Jun Liang Liu ◽  
Yuan Zhang ◽  
Yong Hui Hu
Keyword(s):  
Fractal Geometry ◽  
Output Signal ◽  
Signal To Noise Ratio ◽  
High Order ◽  
Main Peak ◽  
Signal To Noise ◽  
Binary Offset Carrier ◽  
Simulation Results ◽  
Modulated Signals ◽  
Acquisition Method

This paper proposes an improved acquisition method for high-order binary-offset-carrier (BOC) modulated signals based on fractal geometry. We introduced the principle of our acquisition method, and outlined its framework. We increase the main peak to side peaks ratio in the BOC autocorrelation function (ACF), with a simple fractal geometry transform. The proposed scheme is applicable to both generic high-order sine-and cosine-phased BOC-modulated signals. Simulation results show that the proposed method increases output signal to noise ratio (SNR).

The Study of Coded CPM Schemes

2012 ◽  
Vol 198-199 ◽  
pp. 1408-1412
Author(s):  
Lin Bo Su ◽  
Jian Hua Chen ◽  
Ying Peng Hu
Keyword(s):  
Fading Channels ◽  
Convolutional Codes ◽  
Continuous Phase ◽  
Coded Modulation ◽  
Superior Performance ◽  
Continuous Phase Modulation ◽  
Codes Over Rings ◽  
Constant Envelope ◽  
Modulation Schemes ◽  
Serially Concatenated

Continuous Phase Modulation (CPM) schemes belong to a class of constant-envelope digital modulation schemes, the constant-envelope nature of the CPM signals makes them robust for the nonlinear and fading channels, and very useful for the satellite and/or the mobile radio channels. Comparing to PSK modulation, CPM modulation can not only provide spectral economy, but also exhibit a “coding gain”. CPM can be decomposed into a Continuous Phase Encoder (CPE) followed by a Memoryless Modulator (MM), this allows many new coded modulation schemes of combination of convolutional encoder and CPM modulator to be possible, such as serially-concatenated CPM (SC-CPM), SC-CPM with Convolutional Codes over Rings, pragmatic CPM (P-CPM), Concatenation of convolutional endocder and extended CE（CCEC）, etc. Some simulations show that these new CPM schemes can offer superior performance.

Effects of Cont Rail Joint Type on Bus Rollover Crashworthiness

2014 ◽  
Vol 945-949 ◽  
pp. 156-161
Author(s):  
Han Chi Hong ◽  
Hong Wu Huang
Keyword(s):  
Design Guidelines ◽  
Finite Element Models ◽  
Initial Condition ◽  
Joint Structure ◽  
Calculation Technique ◽  
Adams Software ◽  
Residual Space ◽  
Simulation Results ◽  
Ece R66 ◽  
Energy Absorbing

Three finite element models of bus with difference types of cant rail joint were developed and the rollover crashworthiness of buses was simulated by LS_DYNA according to ECE R66. The calculation technique was validated by the tests of three separate specimens, which were extracted from the bus superstructure. The velocity of bus just before impact for rollover, were calculated using ADAMS software and then used as initial condition for the LS_DYNA analysis. No intrusion was found in the residual space of three bus models during rollover test simulation. The energy absorbing capacity and distortion configuration were investigated. The simulation results shown that the cont rail joint structure played an important part in energy absorbing during bus rollover accident, and would contribute to some design guidelines for bus rollover crashworthiness.

THE ANALYTICAL MODEL OF NOISE IMMUNITY CALCULATION OF COMMUNICATION SYSTEMS WITH MULTI-POSITION TYPES OF MODULATION AND CONVOLUTIONAL CODING

2020 ◽  
Author(s):  
Э.Б. ЛИПКОВИЧ ◽  
А.А. СЕРЧЕНЯ
Keyword(s):  
Computer Simulations ◽  
Communication Systems ◽  
Error Probability ◽  
Noise Immunity ◽  
Convolutional Code ◽  
Analytical Models ◽  
Signal To Noise ◽  
Probability Of Error ◽  
Information Efficiency ◽  
Convolutional Coding

Получены математические модели расчета отношений сигнал/шум и несущая/шум, требуемые для обеспечения заданной вероятности ошибки на выходе декодера с «мягким» решением, без необходимости вычисления коэффициентов спектра сверточного кода и выполнения процедур компьютерного моделирования характеристик помехоустойчивости. Приведены расчетные выражения для определения исправляющей способности декодера, энергетического выигрыша от кодирования и информационной эффективности систем связи в зависимости от параметров многопозиционных видов модуляции, сверточного кодирования и вероятности ошибки в информационном бите. По полученным аналитическим моделям построены зависимости и дана оценка результатов исследований. Mathematical models are obtained for calculating signal-to-noise and carrier-to-noise ratios required to provide a given error probability at the decoder output with a “soft” solution and without calculating the convolutional code spectrum coefficients and performing computer simulations of noise immunity characteristics. Calculation expressions are given to determine the correcting ability of the decoder, the energy gain from coding, and the information efficiency of communication systems depending on the parameters of multi-position types of modulation, convolutional coding, and the probability of error in the information bit. Dependencies are constructed according to the obtained analytical models and the research results are evaluated.

scholarly journals Sub-Sonic Linear Synchronous Motors Using Superconducting Magnets for the Hyperloop

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4611 ◽  
Author(s):  
Su Y. Choi ◽  
Chang Y. Lee ◽  
Jung M. Jo ◽  
Jae H. Choe ◽  
Ye Jun Oh ◽  
...  
Keyword(s):  
Superconducting Magnets ◽  
Design Guidelines ◽  
Design Methods ◽  
Design Models ◽  
Synchronous Motors ◽  
Simulation Results ◽  
Test Beds ◽  
Linear Synchronous Motors ◽  
Magnetic Resistance ◽  
Supply Systems

Sub-sonic linear synchronous motors (LSMs) with high-temperature superconducting (HTS) magnets, which aim to accelerate to a velocity of 1200 km/h in the near-vacuum tubes of 0.001 atm for the Hyperloop, are newly introduced in this paper. By the virtue of the combination of LSMs and electrodynamic suspensions (EDSs) with HTS magnets, a large air-gap of 24 cm, low magnetic resistance forces of below 2 kN, and the efficient as well as practical design of propulsion power supply systems of around 10 MVA could be guaranteed at a sub-sonic velocity. The characteristics of the proposed LSMs with HTS magnets, in addition, are widely analyzed with theories and simulation results. Optimal design methods for LSMs and inverters, which account for more than half of the total construction cost, are introduced with design guidelines and examples for the commercialization version of the Hyperloop. At the end of the paper, in order to verify the proposed design models of the sub-sonic LSMs, two different test-beds—i.e., 6 m long static and 20 m long dynamic propulsion test-beds—are fabricated, and it is found that the experimental results are well matched with proposed design models as well as simulation results; therefore, the design methods constitute guidelines for the design of sub-sonic LSMs for the Hyperloop.

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