scholarly journals An Improved M-ary Modulation Scheme Based on Chaotic Dynamics

2019 ◽  
Vol 4 (2019) ◽  
pp. 13-19
Author(s):  
Hikmat N. Abdullah ◽  
Asaad H. Sahar ◽  
Thamir R. Saeed
Keyword(s):  
Chaotic Dynamics ◽  
Modulation Scheme ◽  
System Complexity ◽  
Chaotic Sequences ◽  
Simulation Results ◽  
Traditional Counterpart ◽  
Coherent Modulation

This paper proposes an improved chaos-based M-ary modulation system. It reproduces deterministic chaotic dynamics to create M-ary non-coherent modulation. The proposed modulation system transmits data using autonomous chaotic sequences. It separates the chaotic dynamics through the use of interleavers and realigns them through the use deinterleavers. The simulation results show that the improved scheme overperforms its traditional counterpart. The degree of improvement grows as the M-ary order is increased, with a penalty of increased system complexity.

ADAPTIVE IDENTIFICATION ALGORITHMS FOR AR SYSTEM DRIVEN BY CHAOTIC SEQUENCE

2003 ◽  
Vol 13 (04) ◽  
pp. 963-972 ◽  
Author(s):  
BAO-YUN WANG ◽  
T. W. S. CHOW ◽  
K. T. NG
Keyword(s):  
Communication System ◽  
Adaptive Algorithms ◽  
Chaotic Sequence ◽  
Estimation Accuracy ◽  
Chaotic Communication ◽  
Adaptive Identification ◽  
System Parameters ◽  
Chaotic Sequences ◽  
Simulation Results ◽  
Typical Method

In this article the identification of AR system driven by chaotic sequences is addressed. This problem emerges in chaotic communication system, in which chaos-modulated signal passes through a channel described as an AR system. Two adaptive algorithms are presented to tackle this problem. Compared with the existing algorithms such as MPSV and MNPE, the proposed algorithms have very low computational complexities and can be used to track the system parameters in a slowly time-variant environment. The obtained simulation results illustrate that the proposed scheme can offer a better estimation accuracy than the conventional typical method in the high SNR case.

A Pneumatic On-Off Vehicle Suspension System

1977 ◽  
Vol 99 (2) ◽  
pp. 130-136 ◽  
Author(s):  
D. L. Klinger ◽  
A. J. Calzado
Keyword(s):  
Vibration Isolation ◽  
Relative Displacement ◽  
Disturbance Attenuation ◽  
Vehicle Suspension ◽  
System Complexity ◽  
Pressure Transducers ◽  
Control Signals ◽  
Pneumatic Suspension ◽  
Simulation Results ◽  
Vehicle Suspension System

An active, nonlinear, pneumatic suspension applicable to passenger railcars is described. Standard on-off valves modulate pressure differences between dual opposing airbags to attenuate vibration and create guidance forces. Improved vibration isolation over that of conventional passive suspensions is achieved at low power levels. Guidance forces are provided with small suspension travel using short bursts of compressed air taken from vehicle supply reservoirs. Acceleration, relative displacement, and pressure transducers provide the control signals required for stabilization, feedforward guidance commands, and disturbance attenuation. Simulation results indicate that performance comparable to hydraulic servosystems can be attained with substantially reduced system complexity and power requirements.

scholarly journals Hybrid Chirp Signal Design for Improved Long-Range (LoRa) Communications

Signals ◽  
2022 ◽  
Vol 3 (1) ◽  
pp. 1-10
Author(s):  
Md. Noor-A-Rahim ◽  
M. Omar Khyam ◽  
Apel Mahmud ◽  
Xinde Li ◽  
Dirk Pesch ◽  
...  
Keyword(s):  
Long Range ◽  
Bit Error Rate ◽  
Modulation Scheme ◽  
Signal Design ◽  
Chirp Signal ◽  
Performance Gain ◽  
Extensive Simulation ◽  
Noise Interference ◽  
Chirp Signals ◽  
Simulation Results

Long-range (LoRa) communication has attracted much attention recently due to its utility for many Internet of Things applications. However, one of the key problems of LoRa technology is that it is vulnerable to noise/interference due to the use of only up-chirp signals during modulation. In this paper, to solve this problem, unlike the conventional LoRa modulation scheme, we propose a modulation scheme for LoRa communication based on joint up- and down-chirps. A fast Fourier transform (FFT)-based demodulation scheme is devised to detect modulated symbols. To further improve the demodulation performance, a hybrid demodulation scheme, comprised of FFT- and correlation-based demodulation, is also proposed. The performance of the proposed scheme is evaluated through extensive simulation results. Compared to the conventional LoRa modulation scheme, we show that the proposed scheme exhibits over 3 dB performance gain at a bit error rate of 10−4.

scholarly journals A Method of Constructing Measurement Matrix for Compressed Sensing by Chebyshev Chaotic Sequence

Entropy ◽  
2020 ◽  
Vol 22 (10) ◽  
pp. 1085
Author(s):  
Renjie Yi ◽  
Chen Cui ◽  
Yingjie Miao ◽  
Biao Wu
Keyword(s):  
Compressed Sensing ◽  
High Probability ◽  
Hardware Implementation ◽  
Electric Circuit ◽  
Chaotic Sequence ◽  
Measurement Matrix ◽  
Chaotic Sequences ◽  
Reconstruction Performance ◽  
Simulation Results ◽  
Sample Distance

In this paper, the problem of constructing the measurement matrix in compressed sensing is addressed. In compressed sensing, constructing a measurement matrix of good performance and easy hardware implementation is of interest. It has been recently shown that the measurement matrices constructed by Logistic or Tent chaotic sequences satisfy the restricted isometric property (RIP) with a certain probability and are easy to be implemented in the physical electric circuit. However, a large sample distance that means large resources consumption is required to obtain uncorrelated samples from these sequences in the construction. To solve this problem, we propose a method of constructing the measurement matrix by the Chebyshev chaotic sequence. The method effectively reduces the sample distance and the proposed measurement matrix is proved to satisfy the RIP with high probability on the assumption that the sampled elements are statistically independent. Simulation results show that the proposed measurement matrix has comparable reconstruction performance to that of the existing chaotic matrices for compressed sensing.

scholarly journals Chaos Synchronization between Fractional-Order Unified Chaotic System and Rossler Chaotic System

2012 ◽  
Vol 562-564 ◽  
pp. 2088-2091
Author(s):  
Xian Yong Wu ◽  
Yi Long Cheng ◽  
Kai Liu ◽  
Xin Liang Yu ◽  
Xian Qian Wu
Keyword(s):  
Fractional Order ◽  
Chaotic System ◽  
Chaos Synchronization ◽  
Chaotic Dynamics ◽  
Chaotic Attractors ◽  
System Parameters ◽  
Unified Chaotic System ◽  
Simulation Results ◽  
Drive Systems ◽  
Asymptotic Synchronization

The chaotic dynamics of the unified chaotic system and the Rossler system with different fractional-order are studied in this paper. The research shows that the chaotic attractors can be found in the two systems while the orders of the systems are less than three. Asymptotic synchronization of response and drive systems is realized by active control through designing proper controller when system parameters are known. Theoretical analysis and simulation results demonstrate the effective of this method.

DYNAMICAL CHARACTERISTICS OF DISCRETIZED CHAOTIC PERMUTATIONS

2002 ◽  
Vol 12 (10) ◽  
pp. 2087-2103 ◽  
Author(s):  
NAOKI MASUDA ◽  
KAZUYUKI AIHARA
Keyword(s):  
Invariant Measure ◽  
Periodic Orbit ◽  
Lyapunov Exponents ◽  
Chaos Theory ◽  
Chaotic Dynamics ◽  
Invariant Measures ◽  
Random Sequences ◽  
Dynamical Characteristics ◽  
Chaotic Sequences ◽  
Continuous State

Chaos theory has been applied to various fields where appropriate random sequences are required. The randomness of chaotic sequences is characteristic of continuous-state systems. Accordingly, the discrepancy between the characteristics of spatially discretized chaotic dynamics and those of original analog dynamics must be bridged to justify applications of digital orbits generated, for example, from digital computers simulating continuous-state chaos. The present paper deals with the chaotic permutations appearing in a chaotic cryptosystem. By analysis of cycle statistics, the convergence of the invariant measure and periodic orbit skeletonization, we show that the orbits in chaotic permutations are ergodic and chaotic enough for applications. In the consequence, the systematic differences in the invariant measures and in the Lyapunov exponents of two infinitesimally L∞-close maps are also investigated.

scholarly journals Hybrid Chirp Signal Design for Improved Long-Range (LoRa) Communications

2021 ◽  
Author(s):  
Md. Noor-A-Rahim ◽  
Mohammad Omar Khyam ◽  
Apel Mahmud ◽  
Xinde Li ◽  
Dirk Pesch ◽  
...  
Keyword(s):  
Long Range ◽  
Bit Error Rate ◽  
Modulation Scheme ◽  
Signal Design ◽  
Chirp Signal ◽  
Performance Gain ◽  
Extensive Simulation ◽  
Noise Interference ◽  
Chirp Signals ◽  
Simulation Results

Long-range (LoRa) communication has attracted much attention recently due to its application for many Internet of Things applications. However, one of the key problems of the LoRa technology is it is vulnerable to noise/interference due to the use of only up-chirp signals during modulation. In this paper, to solve this problem, unlike the conventional LoRa modulation scheme, we propose a modulation scheme for LoRa communication based on joint up- and down-chirps. A fast Fourier transform (FFT) based demodulation scheme is devised to detect modulated symbols. To further improve demodulation performance, a hybrid demodulation scheme, comprised of FFT and correlation-based demodulation is also proposed. The performance of the proposed scheme is evaluated through extensive simulation results. Compared to the conventional LoRa modulation scheme, we show that the proposed scheme exhibits over 3 dB performance gain at bit error rate of 10^-4.

scholarly journals 5G UFMC Scheme Performance with Different Numerologies

Electronics ◽  
2021 ◽  
Vol 10 (16) ◽  
pp. 1915
Author(s):  
Lambros Sakkas ◽  
Eleftherios Stergiou ◽  
Georgios Tsoumanis ◽  
Constantinos T. Angelis
Keyword(s):  
Mobile Communications ◽  
Bit Error Rate ◽  
Communication Systems ◽  
Modulation Scheme ◽  
Fifth Generation ◽  
Data Rates ◽  
The World ◽  
Simulation Results ◽  
5G Systems ◽  
Ber Performance

5G is the latest mobile communications standard that is spreading fast across the world. Recently defined requirements for 5G systems have led to higher applications’ requirements regarding data rates, lower requirements for latency, and higher efficiency regarding the spectrum usage. Universal Filtered Multi-Carrier (UFMC) is one new candidate modulation scheme for emergent Fifth Generation (5G) communication systems. This paper focuses on Universal Filtered Multi-Carrier (UFMC) design aspects in terms of Bit Error Rate (BER) performance in relation to the filter length used in subband filtering. Simulation results show that BER and CCDF performance varies for different filter lengths and modulation schemes. The main achievement of this work is that the results show that different Dolph–Chebyshev FIR filter lengths do not affect the BER performance both for the 64 and 256 QAM.

scholarly journals Investigation of Ber Performances in Chaotic-Secured Optical Fiber Communication Systems using the 4-PAM Modulation Scheme

2021 ◽  
Vol 19 (6.2) ◽  
pp. 33
Author(s):  
Vu Anh Dao ◽  
Tran Thi Thanh Thuy ◽  
Truong Cao Dung ◽  
Nguyen Xuan Quyen
Keyword(s):  
Optical Fiber ◽  
Communication Systems ◽  
Optical Fiber Communication ◽  
Pulse Amplitude ◽  
Modulation Scheme ◽  
Pulse Amplitude Modulation ◽  
Bit Rate ◽  
Fiber Communication ◽  
Fiber Channel ◽  
Simulation Results

This paper presents a numerical simulation investigation on the bit error rate in a chaotic-secured fiber channel and a conventional fiber channel when propagating independently. The investigated communication system uses the pulse-amplitude modulation scheme (4-PAM) at the bit rate of 10 Gbps, the fiber length of 100 km, and the operation wavelength of 1550 nm. Our simulation results demonstrate both chaotic and non-chaotic transmission channels can well operate with the bit rate up to 20 Gbps with the BER smaller than 10-5 if dispersion and fiber loss issues are appropriately compensated without needing forwarderror-correction, showing high potential in physically secured optical fiber communication systems.

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