This paper discusses the possible application of an innovative set of binary sequences, the De Bruijn ones, as spreading codes in satellite navigation systems. Binary De Bruijn sequences feature inherent Zero Correlation Zone property, that may be effectively exploited to strongly limit the impact of multipath and interference. Simulation results are presented, referred to span 5 De Bruijn sequences, to show the orthogonality and correlation-related properties of these codes, that may properly fit the requirements of satellite based navigation systems.
In this paper, a novel computationally affordable method to generate long binary sequences featuring desired properties is presented, based on the use of a number of shorter non linear binary sub-sequences. The paper shows the relationship of the Auto- and Cross-Correlation (AC, CC) ofthe generated long binary sequences with the AC and CC ofconstituent sub-sequences. It is also shown that the starting bit position of sub-sequences has an important role on AC and CC of the generated sequences. To generate the optimal long binary sequence from correlation points of view, Particle Swarm Optimization (PSO) algorithm is employed. All the techniques stated in the literature to improve the PSO are implemented and it is clearly shown that the constriction factor and the variable population size turn out to have a great impact on minimizing the fitness function (RMS of AC) representing the target Correlationproperties expected for the resulting long sequence. Possible application scenarios for the long sequences generated by the proposed method are also discussed and evaluated.
This paper investigates the use of binary De Bruijn sequences as vehicle signatures in a vehicular CDMA communication framework, over Rayleigh and Weibull distributed fading channels. Orthogonal De Bruijn codes are able to outperform Orthogonal Variable Spreading Factor sequences, whereas it is shown that their inherent Zero Correlation Zone does not provide any significant advantages in the presence of severe fading.
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