Performance analysis for a chaos-based code-division multiple access system in wide-band channel (original) (raw)
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A Methodology for Bit Error Rate Prediction in Chaos-based Communication Systems
Circuits, Systems and Signal Processing, 2009
This paper is devoted to the derivation of an exact analytical expression of the bit error rate for chaos-based DS-CDMA systems. For the studied transmission system, we suppose that synchronization is achieved perfectly, coherent reception is considered, and an Additive White Gaussian Noise channel (AWGN) is assumed. In the first part of the paper, performance of a mono-user system with different chaotic sequences is evaluated and compared in terms of the error probability. This comparison is realized thanks to the probability density function of the bit energy of a chaotic sequence. The bit error rate can be easily derived by numerical integration. In some particular cases, for certain chaotic sequences with known probability density function of bit energy, we propose an analytical expression of the bit error. In the second part of the paper, the performance of a chaos-based DS-CDMA system is evaluated in the multi-user case. A general conclusion is that probability density function of chaos bit energy, for a given spreading factor, can give a clear idea about how to choose a "good" chaotic sequence for improving the performance of the chaos-based CDMA system.
Signal Processing, 2010
In this paper, we present a study of the bit error rate (BER) performance of chaos-based DS-CDMA system over an m-distributed fading channel. In this system, the perfect synchronization between receiver and transmitter is assumed. The transmitted bit energy after spreading by chaotic signal is not considered as constant in order to evaluate with precision the BER for such system. The performance of chaos-based DS-CDMA system is examined first in mono-user case. An approximation of the received bit energy by a known distribution leads to an accurate analytical BER expression. This BER computation approach is generalized for asynchronous multi-user case. The performance of DS-CDMA system using Gold sequence is compared and discussed to chaos-based DS-CDMA system. A perfect match between simulations and analytical BER expressions confirms the exactitude of our approach.
Accurate Bit Error Rate Calculation for Asynchronous Chaos-Based DS-CDMA over Multipath Channel
EURASIP Journal on Advances in Signal Processing, 2009
An accurate approach to compute the bit error rate expression for multiuser chaosbased DS-CDMA system is presented in this paper. For more realistic communication system a slow fading multipath channel is considered. A simple RAKE receiver structure is considered. Based on the bit energy distribution, this approach compared to others computation methods existing in literature gives accurate results with low computation charge. Perfect estimation of the channel coefficients with the associated delays and chaos synchronization is assumed. The bit error rate is derived in terms of the bit energy distribution, the number of paths, the noise variance, and the number of users. Results are illustrated by theoretical calculations and numerical simulations which point out the accuracy of our approach.
In this paper a coherent reception of direct sequence-code division multiple access (DS-CDMA) in multi user case (MU) is considered, when chaotic sequences are used instead of conventional pseudo-noise (PN) spreading codes. A piecewise linear map (PWL) is used as chaotic spreading sequence (CSS). Additive white Gaussian noise channel (AWGN) is assumed. An analytical expression of the bit error rate in the multi user case is presented.
Analytical calculation of BER in communication systems using a piecewise linear chaotic map
2007 18th European Conference on Circuit Theory and Design, 2007
The coherent reception of direct sequence-code division multiple access (DS-CDMA) is considered, when chaotic sequences are used instead of conventional pseudo-noise (PN) spreading code. A piecewise linear map (PWL) is used as chaotic spreading sequence (CSS). Additive white Gaussian noise channel (AWGN) is assumed. An analytical expression of the bit error rate in the single user case is presented.
The performance of any communication system is assessed by its bit error rate (BER). Energy to Noise ratio plays an important role in evaluation of a communication system. The application of chaos based communication system is very popular. To check the relationship between energy to noise ratio and BER, WCDMA downlink simulation model as per 3gpp specification is used with chaos codes along OVSF spreading codes. Simulation is done in the presence of an additive white Gaussian noise (AWGN) channel along with QPSK modulation. The simulations and Bit Error Rate (BER) evaluation with respect to Energy-To-Noise ratio are performed using MATLAB. The researcher developed the regression model to find the effect of chaotic modulation on bit error rate performance in direct sequence spread spectrum communication.
Chaos-Based Digital Communication Systems with Low Data-Rate Wireless Applications
2018
This chapter presents a study on the modeling and performance evaluation of chaos-based coherent and incoherent systems, i.e., chaotic direct-sequence code-division multiple-access (CDS-CDMA) and differential chaos-shift keying (DCSK), for low-data-rate applications in wireless communications. This study is motivated by the design of a secure physical layer for wireless-based applications with low data rate and in small transmission areas. A wireless channel affected by noise, fading, multipath, and delay-spread for low-data-rate transmission of chaotically spreading signals is described and mathematically modeled. Discrete-time models for the transmitter and receiver of CDS-CDMA and DCSK systems under the impact of the wireless channel are developed. Bit error rate (BER) performance of the systems is estimated by means of both theoretical derivation and discrete integration. Simulated performances are shown and compared with the corresponding estimated ones, where the effects of th...
Performance of multi-user chaos-based DS-CDMA system over multipath channel
2009 IEEE International Symposium on Circuits and Systems, 2009
In this paper, we propose a new approach to compute the exact bit error rate expression for asynchronous chaos-based DS-CDMA system over multipath channel. Perfect estimation of the channel coefficients with the associated delays and chaos synchronization are assumed. A simple RAKE receiver structure is considered. A stationary multipath channel with constant gain is assumed. An asynchronous multi-user chaosbased DS-CDMA system is then defined and the BER is derived in terms of the energy distribution, the number of paths, the noise variances, and the number of users.
Chaos Communication Performance: Theory and Computation
Circuits, Systems, and Signal Processing, 2011
In this paper new and existing approaches are developed to compute the bit error rate for chaos-based communication systems. The multi-user coherent antipodal chaos shift keying system is studied and evaluated in its coherent form, in the sense of perfect synchronization between transmitted and received chaotic sequences. Transmission is through an additive white Gaussian noise channel. Four methods are interrelated in the paper, three approximate ones and an exact one. The least accurate but most well known is based on simple Gaussian approximation; this is generalized to better reveal its structure. Two accurate and computationally efficient approximate methods are based on conditional Gaussian approximation and the statistical distribution of the typically non-constant bit energy. The most insightful but computationally expensive one is based on exact theory and rests on explicit mathematical results for particular chaotic maps used to spread binary messages. Both upper and lower bounds to the bit error rate are suggested. The relative advantages of the different approaches are illustrated with plots of bit error rate against signal to noise ratio.
Performance Analysis of Chaotic Spreading Sequence in WCDMA Downlink System
Spreading code plays an important role in WCDMA system. Each user in a cell is separated by a unique spread code. WCDMA system generally uses PN sequence such as Walsh codes or gold codes as spread code. In this paper, the chaotic spreading sequence is used as spread code instead of Walsh codes and the chaotic signal is generated using logistic map. The generated chaotic signal is a real valued signal and it is inappropriate to be used as spreading sequence. Consequently, the chaotic signal is transformed into binary sequence using a threshold function. The performance of chaotic spreading sequence in WCDMA with PN sequences in terms of bit error rate for AWGN channel is presented in this paper.