scholarly journals The Optimal Carrier-Secret Ratio for Wireless Covert Channels Based on Constellation Shaping Modulation

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Sen Qiao ◽  
Guangjie Liu ◽  
Xiaopeng Ji ◽  
Weiwei Liu
Keyword(s):  
Total Power ◽  
Covert Communication ◽  
Transmission Performance ◽  
Covert Channels ◽  
Constellation Shaping ◽  
Communication Technique ◽  
Error Ratio ◽  
Bit Error Ratio ◽  
Simulation Results ◽  
The Impact

Wireless covert communication is an emerging communication technique that prevents eavesdropping. This paper considers the bit error ratio (BER) problem of covert communication based on constellation shaping modulation (CSM). The impact of carrier-secret ratio (CSR) on BER is studied and the approximate solution of optimal CSR is obtained. Then, we extended the conclusion to typical communication scenarios with one and more relays where the undetectability and reliability were analyzed and inspected. It is proved that there also exists the optimal CSR in scenarios with relays. Additionally, it is found that the undetectability under the constraints of constant total power depends on the eavesdropper’s position, and we found an undetectability deterioration area (UDA) in the scenario of relays. Simulation results show the existence of optimal CSR and its impact on transmission performance.

Research on Recognition of the Two-Dimensional Barcode

2012 ◽  
Vol 546-547 ◽  
pp. 582-587
Author(s):  
Xiao Wu Zhang ◽  
Wen Xing Bao ◽  
Hui Pu
Keyword(s):  
Projection Algorithm ◽  
Two Dimensional ◽  
Bar Code ◽  
Error Ratio ◽  
Bit Error Ratio ◽  
Blurred Images ◽  
The Impact

Based on barcode PDF417 image’s characteristics, in order to improve the recognition of bar code, and reduce the bit error ratio, we proposed two methods. One way is to separate the calculation of the width of barcode’s unit from the extract codeword, another is the Recognition of bar blank sequence by using projection algorithm. Thereby, both methods reduce the impact of blurred images made by noisy pollution; the test proved that these two methods can deal with contaminated barcode image effectively.

Effects of ASE on DPSK Modulation Formats with Different Duty-Ratio in Optical Transmission System

2013 ◽  
Vol 385-386 ◽  
pp. 1595-1598
Author(s):  
Jin Hang Hu ◽  
Ya Lin Guan ◽  
Jin Cai Lin
Keyword(s):  
Optical Networks ◽  
Optical Fiber Communication ◽  
Duty Ratio ◽  
Modulation Formats ◽  
Differential Phase Shift ◽  
Fiber Communication ◽  
Error Ratio ◽  
Bit Error Ratio ◽  
Shift Keying ◽  
The Impact

In optical networks, erbium-doped fiber amplifiers (EDFAs) are used to provide a wide and flat gain spectrum. Amplified Spontaneous Emission (ASE) emitted from EDFA adds to signal and grows rapidly. This accumulated ASE noise may limit the effective amplification due to saturation effect and affects the receivers bit error ratio (BER). In this paper, we show the impact of ASE noise in transmission fiber by using three different modulation formats: 33%DPSK, 66%DPSK and DPSK. In recent years, optical fiber communication system began to use the DPSK (Differential Phase Shift Keying) format to replace the traditional OOK format, which has been intensively investigated in numerical and experimental works.

scholarly journals Mitigation of Nonlinear Phase Noise in Single-channel Coherent 16-QAM Systems Employing Logistic Regression

2021 ◽  
Author(s):  
Romulo de Paula ◽  
Lucas Marim ◽  
Rafael Penchel ◽  
Yessica Rumaldo Bustamante ◽  
Marcelo Francisco Luis Abbade ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Phase Noise ◽  
Phase Modulation ◽  
Performance Enhancement ◽  
Single Channel ◽  
Nonlinear Phase ◽  
Error Ratio ◽  
Bit Error Ratio ◽  
The Impact ◽  
System Operating

Abstract We propose and analyze a classier based on logistic regression (LR) to mitigate the impact of nonlinear phase noise (NPN) caused by Kerr induced self-phase-modulation in digital coherent systems with single-channel unrepeated links. Simulation results reveal that the proposed approach reduces the bit error ratio (BER) in a 100-km-long 16 quadrature amplitude modulation (16-QAM) system operating at 56-Gbps. Thus, the BER is reduced from 6.88·10 -4 when using maximum likelihood to 4.27·10 -4 after applying the LR-based classification, representing an increase of 0.36 dB in the effective Q-factor. This performance enhancement is achieved with only 624 operations per symbol, which can be easily parallelized into 16 lines of 39 operations.

Study on a New Joint Source-Channel Decoder Design

2013 ◽  
Vol 340 ◽  
pp. 471-475
Author(s):  
Fei Zhong ◽  
Shu Xu Guo
Keyword(s):  
Iterative Decoding ◽  
Ldpc Codes ◽  
Low Density ◽  
Parity Check ◽  
Information Redundancy ◽  
Low Density Parity Check ◽  
Error Ratio ◽  
Bit Error Ratio ◽  
Simulation Results ◽  
Decoder Design

To improve upon the Low-Density Parity-Check (LDPC) codes , incorporating compressed sensing (CS) and information redundancy, a new joint decoding algorithm frame is presented. The proposed system exploits the information redundancy by CS reconstruction during the iterative decoding process to correct decoding of LDPC codes. The simulation results show that the algorithm presented can improve system decoding performance and obviously make bit error ratio (BER) lower then traditional LDPC codes. In addition, a relatively short argument is given on different CS reconstructed algorithms in proposed system, the new design is shown to benefit from different CS reconstructed algorithms.

scholarly journals Investigation of EDFA Performance in DWDM Transmission Systems Under Different Operating Conditions

2019 ◽  
Vol 56 (2) ◽  
pp. 42-53
Author(s):  
J. Putrina ◽  
S. Olonkins ◽  
V. Bobrovs ◽  
J. Porins
Keyword(s):  
Operating Conditions ◽  
Power Penalty ◽  
Channel Spacing ◽  
Transmission Systems ◽  
Error Ratio ◽  
Bit Error Ratio ◽  
The Impact

Abstract The article investigates dependence of EDFA performance on its operating conditions. First of all, the impact of changes in channel spacing on the quality of the amplifier signal and on the desired EDFA configuration is observed – three different values of channel spacing are considered – 37.5 GHz, 50 GHz and 100 GHz. Afterwards, the impact of EDFA positioning on the quality of the amplified signal and the desired configuration is assessed. Three different EDFA positioning scenarios are considered – when the EDFA is used as a power booster, as an in-line amplifier and as a preamplifier. In all cases, such configuration of the EDFA is found that can ensure bit-error ratio (BER) values below 1·10−9 in all channels of the system. To assess the performance of the amplifiers, power penalty values are obtained in respect to identical transmission systems but without amplification.

Comparison of Orthogonal Transforms for OFDM Communication System

1970 ◽  
Vol 111 (5) ◽  
pp. 77-80 ◽  
Author(s):  
A. Aboltins
Keyword(s):  
Communication System ◽  
Communication Systems ◽  
Average Power ◽  
Communication Channels ◽  
Power Ratio ◽  
Frequency Division ◽  
Error Ratio ◽  
Bit Error Ratio ◽  
Simulation Results ◽  
Orthogonal Transforms

Classical orthogonal frequency division (OFDM) employs fast Fourier transform (FFT) for elimination of inter-symbol interference (ISI) and expansion of time support of the transmitted signals. However FFT could not always be optimal in terms bit error ratio (BER) due channel variations, Doppler Effect, nonlinearities and high peak-to-average power ratio of the signal. Aim of this publication is to experimentally compare different orthogonal transforms and outline impact of these transforms on BER of the communication system with noisy, frequency selective and nonlinear communication channels. Simulation results of OFDM communication systems with equalization and no transform, with FFT, Hadamard and Generalized nonsinusoidal orthogonal transforms are presented. Ill. 5, bibl. 9, tabl. 1 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.111.5.361

scholarly journals Measuring Hydrometeors Using a Precipitation Microphysical Characteristics Sensor: Sampling Effect of Different Bin Sizes on Drop Size Distribution Parameters

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Xichuan Liu ◽  
Taichang Gao ◽  
Yuntao Hu ◽  
Xiaojian Shu
Keyword(s):  
Drop Size ◽  
Rain Rate ◽  
Monte Carlo Model ◽  
Rain Gauge ◽  
Sampling Schemes ◽  
Distribution Parameters ◽  
Optimum Sampling ◽  
Simulation Results ◽  
The Impact ◽  
Good Agreement

In order to improve the measurement of precipitation microphysical characteristics sensor (PMCS), the sampling process of raindrops by PMCS based on a particle-by-particle Monte-Carlo model was simulated to discuss the effect of different bin sizes on DSD measurement, and the optimum sampling bin sizes for PMCS were proposed based on the simulation results. The simulation results of five sampling schemes of bin sizes in four rain-rate categories show that the raw capture DSD has a significant fluctuation variation influenced by the capture probability, whereas the appropriate sampling bin size and width can reduce the impact of variation of raindrop number on DSD shape. A field measurement of a PMCS, an OTT PARSIVEL disdrometer, and a tipping bucket rain Gauge shows that the rain-rate and rainfall accumulations have good consistencies between PMCS, OTT, and Gauge; the DSD obtained by PMCS and OTT has a good agreement; the probability of N0, μ, and Λ shows that there is a good agreement between the Gamma parameters of PMCS and OTT; the fitted μ-Λ and Z-R relationship measured by PMCS is close to that measured by OTT, which validates the performance of PMCS on rain-rate, rainfall accumulation, and DSD related parameters.

scholarly journals A New Method to Determine the Impact of Individual Field Quantities on Cycle-to-Cycle Variations in a Spark-Ignited Gas Engine

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4136
Author(s):  
Clemens Gößnitzer ◽  
Shawn Givler
Keyword(s):  
Kinetic Energy ◽  
Flow Field ◽  
Turbulent Kinetic Energy ◽  
Negative Impact ◽  
Operating Conditions ◽  
Engine Operation ◽  
Gas Engine ◽  
Cycle Simulation ◽  
Simulation Results ◽  
The Impact

Cycle-to-cycle variations (CCV) in spark-ignited (SI) engines impose performance limitations and in the extreme limit can lead to very strong, potentially damaging cycles. Thus, CCV force sub-optimal engine operating conditions. A deeper understanding of CCV is key to enabling control strategies, improving engine design and reducing the negative impact of CCV on engine operation. This paper presents a new simulation strategy which allows investigation of the impact of individual physical quantities (e.g., flow field or turbulence quantities) on CCV separately. As a first step, multi-cycle unsteady Reynolds-averaged Navier–Stokes (uRANS) computational fluid dynamics (CFD) simulations of a spark-ignited natural gas engine are performed. For each cycle, simulation results just prior to each spark timing are taken. Next, simulation results from different cycles are combined: one quantity, e.g., the flow field, is extracted from a snapshot of one given cycle, and all other quantities are taken from a snapshot from a different cycle. Such a combination yields a new snapshot. With the combined snapshot, the simulation is continued until the end of combustion. The results obtained with combined snapshots show that the velocity field seems to have the highest impact on CCV. Turbulence intensity, quantified by the turbulent kinetic energy and turbulent kinetic energy dissipation rate, has a similar value for all snapshots. Thus, their impact on CCV is small compared to the flow field. This novel methodology is very flexible and allows investigation of the sources of CCV which have been difficult to investigate in the past.

A Dicode Signaling Scheme for Capacitively Coupled Interface

2011 ◽  
Vol 497 ◽  
pp. 296-305
Author(s):  
Yasushi Yuminaka ◽  
Kyohei Kawano
Keyword(s):  
Partial Response ◽  
Data Transmission ◽  
High Speed ◽  
Circuit Simulation ◽  
Frequency Bandwidth ◽  
Capacitively Coupled ◽  
Limited Frequency ◽  
Simulation Results ◽  
Response Coding ◽  
The Impact

In this paper, we present a bandwidth-efficient partial-response signaling scheme for capacitivelycoupled chip-to-chip data transmission to increase data rate. Partial-response coding is knownas a technique that allows high-speed transmission while using a limited frequency bandwidth, by allowingcontrolled intersymbol interference (ISI). Analysis and circuit simulation results are presentedto show the impact of duobinary (1+D) and dicode (1-D) partial-response signaling for capacitivelycoupled interface.

An Improved Initial Alignment Method of Strap-Down Inertial Navigation System on a Swaying Base

2013 ◽  
Vol 415 ◽  
pp. 143-148
Author(s):  
Li Hua Zhu ◽  
Xiang Hong Cheng
Keyword(s):  
Navigation System ◽  
Inertial Navigation System ◽  
Alignment Algorithm ◽  
Alignment Method ◽  
Initial Alignment ◽  
Vehicle Simulation ◽  
Robust Property ◽  
Simulation Results ◽  
Lever Arm Effect ◽  
The Impact

The design of an improved alignment method of SINS on a swaying base is presented in this paper. FIR filter is taken to decrease the impact caused by the lever arm effect. And the system also encompasses the online estimation of gyroscopes’ drift with Kalman filter in order to do the compensation, and the inertial freezing alignment algorithm which helps to resolve the attitude matrix with respect to its fast and robust property to provide the mathematical platform for the vehicle. Simulation results show that the proposed method is efficient for the initial alignment of the swaying base navigation system.

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