Computer arithmetic, chaos and fractals
CNLS '89 Proceedings of the ninth annual international conference of the Center for Nonlinear Studies on Self-organizing, Collective, and Cooperative Phenomena in Natural and Artificial Computing Networks on Emergent computation
Cascading synchronized chaotic systems
Physica D
An Introduction to Spread-Spectrum Communications
An Introduction to Spread-Spectrum Communications
CDMA Systems Engineering Handbook
CDMA Systems Engineering Handbook
Single and Multi-Carrier CDMA: Multi-User Detection, Space-Time Spreading, Synchronisation and Standards
Chaos-Based Digital Communication Systems: Operating Principles, Analysis Methods, and Performance Evaluation
Robust synchronization for asynchronous multi-user chaos-based DS-CDMA
Signal Processing
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This paper demonstrates a way of achieving and maintaining sequence synchronization in multi-user direct sequence code division multiple access (DS-CDMA) based chaotic communication systems. Synchronization is achieved and maintained through the code acquisition and the code tracking phase, respectively. The performance of the proposed system is evaluated in the presence of additive white Gaussian noise and interuser interferences. Throughout, a pseudo-random binary sequence (PRBS) is used as the synchronizing pilot signal within the multi-user chaotic communication system. In addition, the Logistic and Bernoulli chaotic maps are also used as the pilot signals in the investigation of the code acquisition performance. The code acquisition circuit is evaluated in terms of the probability of detection and probability of false alarm. The corresponding results demonstrate an ability to achieve initial synchronization. Furthermore, it is shown that in terms of code acquisition, the PRBS outperforms the Logistic and Bernoulli chaotic maps. A mathematical model of the code tracking loop is then presented. From the model, a control law for the generation of time offset estimates is derived. The robustness of the synchronization unit is then demonstrated in terms of the bit error rate. It has been shown that for the case of 1, 2, 3, 4, and 5 users, the bit error rate goes below the maximum acceptable limit of 10^-^3 at the bit energy to noise power spectral density ratio of approximately 8, 9, 9.5, 11, and 12dB, respectively. Furthermore, a gradual degradation in performance, above the maximum acceptable bit error rate limit, is demonstrated for the increasing number of users.