scholarly journals Synchronization of Two Chaotic Stream Ciphers in Secure CDMA Communication Systems

2020 ◽  
Vol 10 (4) ◽  
pp. 5947-5952 ◽  
Author(s):  
A. S. Alshammari
Keyword(s):  
Code Division Multiple Access ◽  
Communication Systems ◽  
Multiple Access ◽  
Simple Structure ◽  
Signal To Noise Ratio ◽  
Effective Property ◽  
Chaotic Signals ◽  
Cdma Systems ◽  
Code Division Multiple ◽  
Harmful Effects

In the basic processing of Code Division Multiple Access (CDMA) systems using chaotic code sequences, a pair of chaos generators in the transmitter and the receiver are used to generate the same sequence, in order to synchronize and retrieve the transmitted signals. In addition, a filter with a simple structure should be integrated into chaotic signals to achieve the maximum of the signal to noise ratio and mitigate the harmful effects of multipath. Another effective property of chaos signal is that a wireless multipath channel does not change the amount of contained information. Considering those issues, the present paper describes a practical system for synchronizing two chaotic generators used in a digital CDMA. Chaotic generators were used to spread the data and provide security against attack. Both receiver and transmitter were implemented using two separate Spartan 6 FPGA boards. Experimental results proved the robustness of the proposed method which could contribute towards the synchronization of chaotic signals in secure CDMA communication systems.

scholarly journals Suitable Spreading Sequences for Asynchronous MC-CDMA Systems

2018 ◽  
Vol 3 ◽  
pp. 9-13 ◽  
Author(s):  
Mouad Addad ◽  
Ali Djebbari
Keyword(s):  
Communication Systems ◽  
Multiple Access ◽  
Signal To Noise Ratio ◽  
Multiple Access Interference ◽  
High Data ◽  
Research Areas ◽  
Rate Transmission ◽  
Cdma Systems ◽  
Code Division Multiple ◽  
Spreading Sequences

In order to meet the demand of high data rate transmission with good quality maintained, the multi-carrier code division multiple access (MC-CDMA) technology is considered for the next generation wireless communication systems. However, their high crest factor (CF) is one of the major drawbacks of multi-carrier transmission systems. Thus, CF reduction is one of the most important research areas in MC-CDMA systems. In addition, asynchronous MC-CDMA suffers from the effect of multiple access interference (MAI), caused by all users active in the system. Degradation of the system’s bit error rate (BER) caused by MAI must be taken into consideration as well. The aim of this paper is to provide a comparative study on the enhancement of performance of an MC-CDMA system. The spreading sequences used in CDMA play an important role in CF and interference reduction. Hence, spreading sequences should be selected to simultaneously ensure low CF and low BER values. Therefore, the effect that correlation properties of sequences exert on CF values is investigated in this study. Furthermore, a numerical BER evaluation, as a function of the signal-to-noise ratio (SNR) and the number of users, is provided. The results obtained indicate that a trade-off between the two criteria is necessary to ensure good performance. It was concluded that zero correlation zone (ZCZ) sequences are the most suitable spreading sequences as far as the satisfaction of the above criteria is concerned.

Error Performance of Chaotic Digital Code-Divison Multiple Access (CDMA) Systems

1998 ◽  
Vol 08 (10) ◽  
pp. 2047-2059 ◽  
Author(s):  
Tao Yang ◽  
Leon O. Chua
Keyword(s):  
Channel Capacity ◽  
Code Division Multiple Access ◽  
Communication Systems ◽  
Multiple Access ◽  
Digital Code ◽  
Error Performance ◽  
Interference Level ◽  
Wireless Environments ◽  
Cdma Systems ◽  
Code Division Multiple

Chaotic digital code-division multiple access ((CD)2MA) systems are new types of communication systems using chaotic carriers. (CD)2MA had found applications in both wireless and other communication systems. In this paper we study the error performance of chaotic digical code-division multiple access ((CD)2MA) systems used in both wireless environment and cable networks. We present first the details of the interleave mode of the (CD)2MA. When a (CD)2MA system works in the interleave mode, each of its transmitters only transmits signals during a portion of the bit duration of the message signal. The total interference level is thus reduced which in turn increases the channel capacity. The relationship between the bit error rate (BER) and the interleave rate is studied in both the synchronous (CD)2MA system used in cable systems, and the asynchronous (CD)2MA system used in wireless environments. Our simulation results show that in a cable system the synchronous (CD)2MA system can support 1.5 times more channel capacity than synchronous CDMA systems, and double the channel capacity of CDMA systems in wireless environments.

Chaotic Digital Code-Division Multiple Access (CDMA) Communication Systems

1997 ◽  
Vol 07 (12) ◽  
pp. 2789-2805 ◽  
Author(s):  
Tao Yang ◽  
Leon O. Chua
Keyword(s):  
Code Division Multiple Access ◽  
Communication Systems ◽  
Multiple Access ◽  
Impulsive Control ◽  
Initial Conditions ◽  
Mobile Station ◽  
Digital Code ◽  
Control Scheme ◽  
Cdma Systems ◽  
Code Division Multiple

In this paper, the structure, principle and framework of chaotic digital code-division multiple access ((CD)2 MA) communication systems are presented. Unlike the existing CDMA systems, (CD)2MA systems use continuous pseudo-random time series to spread the spectrum of message signal and the spread signal is then directly sent through a channel to the receiver. In this sense, the carrier used in (CD)2MA is a continuous pseudo-random signal instead of a single tone as used in CDMA. We give the statistical properties of the noise-like carriers. In a (CD)2MA system, every mobile station has the same structure and parameters, only different initial conditions are assigned to different mobile stations. Instead of synchronizing two binary pseudo-random sequences as in CDMA systems, we use an impulsive control scheme to synchronize two chaotic systems in (CD)2MA. The simulation results show that the channel capacity of (CD)2MA is twice as large than that of CDMA.

Robust MVDR Estimation via Polynomial Rooting for MC-CDMA Carrier Frequency Offset

2013 ◽  
Vol 284-287 ◽  
pp. 2687-2693
Author(s):  
Ing Jiunn Su ◽  
Chiao Chan Huang
Keyword(s):  
Carrier Frequency ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Carrier Frequency Offset ◽  
Low Complexity ◽  
Frequency Offset ◽  
High Accuracy ◽  
Cdma Systems ◽  
Code Division Multiple ◽  
Polynomial Rooting

In this letter, we present a blind carrier frequency offset (CFO) estimator by exploiting the polynomial rooting technique for multicarrier-code division multiple access (MC-CDMA) systems. Relative high accuracy and low-complexity to the CFO estimation can be achieved by rooting a polynomial. Simulation results are provided for illustrating the effectiveness of the proposed blind polynomial rooting estimator.

scholarly journals Constructions of asymptotically optimal codebooks with respect to Welch bound and Levenshtein bound

2021 ◽  
Vol 0 (0) ◽  
pp. 0
Author(s):  
Gang Wang ◽  
Deng-Ming Xu ◽  
Fang-Wei Fu
Keyword(s):  
Code Division Multiple Access ◽  
Communication Systems ◽  
Multiple Access ◽  
Cross Correlation ◽  
Hadamard Matrices ◽  
Circulant Matrices ◽  
Asymptotically Optimal ◽  
Welch Bound ◽  
Construction Methods ◽  
Code Division Multiple

<p style='text-indent:20px;'>Codebooks with small maximum cross-correlation amplitudes are used to distinguish the signals from different users in code division multiple access communication systems. In this paper, several classes of codebooks are introduced, whose maximum cross-correlation amplitudes asymptotically achieve the corresponding Welch bound and Levenshtein bound. Specially, a class of optimal codebooks with respect to the Levenshtein bound is obtained. These classes of codebooks are constructed by selecting certain rows deterministically from circulant matrices, Fourier matrices and Hadamard matrices, respectively. The construction methods and parameters of some codebooks provided in this paper are new.</p>

scholarly journals LARGE-SCALE MIMO MC-CDMA SYSTEM USING COMBINED MULTIPLE BEAMFORMING AND SPATIAL MULTIPLEXING

2018 ◽  
Vol 56 (1) ◽  
pp. 102 ◽  
Author(s):  
Nguyen Huu Trung ◽  
Doan Thanh Binh
Keyword(s):  
System Performance ◽  
Code Division Multiple Access ◽  
Communication Systems ◽  
Multiple Access ◽  
Large Scale ◽  
Spatial Multiplexing ◽  
Propagation Loss ◽  
Fifth Generation ◽  
Simulation Results ◽  
Code Division Multiple

This paper proposes a novel Large-scale (massive) Multi-input Multi-output Multi-carrier Code division multiple access (LS MIMO MC-CDMA) model and application to Fifth-Generation Mobile Communication Systems (5G). This system uses combined cylindrical array antenna multiple beamforming architecture with spatial multiplexing. The model is optimized by Min-Max criteria in order to minimize side lobes and maximize compression of propagation loss. The Monte Carlo simulation results unify with the analytical solution for system performance.

Sign in / Sign up

Export Citation Format

Share Document