1,720,962 research outputs found
Generation and Assessment of Binary De Bruijn Sequences and their Applications in Communication Systems
No full textA Software Tool for Quick Codes Analysis and Selection in Spread Spectrum Communication Systems
No full textSpread spectrum communications rely on the selection of suitable sets of so-called spreading codes, also known as signatures, to ensure satisfactory system performance. Comparing different sets of spreading codes may be not a straightforward process, due to the amount of different code-related parameters that should be taken into account, and to the inherent differences in the codes generation algorithms. This paper presents a practical software tool to facilitate the evaluation and comparison of different families of spreading codes, under different parameters and constraints. Simulations to evaluate the selected signatures in a CDMA system, under AWGN or multipath channel, are also supported by the tool. The tool may be usefully applied in the design of communication systems and networks relying upon spread spectrum techniques
Full-length non-linear binary sequences with Zero Correlation Zone for multiuser communications
Get PDFThe research on new sets of sequences that can be applied as spreading codes in multiple user communications is still an active area, even if this topic has been extensively investigated since long time. In fact, new communication paradigms like dense and decentralized wireless networks, where there is no central controller to assign the resources to the nodes, are revamping the interest on finding large sets of sequences providing adequate correlation properties to support a big number of nodes, in potentially hostile channels. This paper focuses on the Zero Correlation Zone (ZCZ) property exhibited by a family of nonlinear binary sequences featuring a great cardinality of their set, and good security-related features, and provides evidence of their suitability to multiuser communications, in channels affected by multipath
A Large Set of Secure Signatures for DS-SS Long Range Radars in Autonomous Cars
Get PDFThe current trend in the use of ICT to boost the development of the automotive sector is mainly ad-
dressed towards so called autonomous vehicles, equipped with appropriate sensors, actuators and processors, that
make them able to move safely, without the intervention of a human driver. Actually, since several years, ICT
permitted a widespread implementation of systems to help the driver maintaining the control of the vehicle, even
when exceeding its normal limits of handling. Among them, vehicle radars may work under all weather conditions,
provide a satisfactory coverage, and see several meters ahead. This paper investigates the performance, in terms
of detection capability and false detection rate, of Direct Sequence Spread Spectrum Long Range Radars adopt-
ing binary De Bruijn sequences as radar signatures, compared to more classical solutions adopting Gold codes.
Following the analysis of the correlation and security properties of De Bruijn sequences, the radar detection per-
formance are discussed in two typical scenarios, and by means of specific tools, such as the ambiguity function to
account for Doppler effects. Even if De Bruijn sequences do not provide disruptive improvements with respect to
Gold codes, they exhibit better behavior in the presence of Doppler, and a much greater cardinality of their set, at
a parity of the length, which may be useful to accommodate many potential users in a vehicular scenario
A New Approach to Sequence Construction With Good Correlation by Particle Swarm Optimization
Get PDFIn 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) of the generated long binary sequences with the AC and CC of constituent 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 Correlation properties expected for the resulting long sequence. Possible application scenarios for the long sequences generated by the proposed method are also discussed and evaluated
A Large Set of Orthogonal Codes for the V2V Scenario
No full textThis 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
De Bruijn sequences for DS/CDMA transmission: Efficient generation, statistical analysis and performance evaluation
No full textNowadays, Direct Sequence Code Division Multiple Access (DS/CDMA) still represents the core technology for the physical layer of several commercially-remunerative applications and standards, ranging from cellular networking, radiolocalization, satellite communications, automotive radar, etc. A very critical issue of Spread Spectrum and CDMA is still represented by the necessity of keeping the probability of intercept as lowest as possible, therefore, a secure information hiding must be guaranteed at the physical layer. The use of De Bruijn binary sequences may represent a valuable solution to the aforesaid issue. De Bruijn sequences are nonlinear shift register sequences, whose sets are characterized by a cardinality much larger than the sequence length. This paper aims at considering some significant aspects about the usage of De Bruijn sequences in DS/CDMA, not yet addressed by prior works: the performance of De Bruijn sequences in asynchronous DS/CDMA transmission is assessed by means of explicit computations of multi-user interference statistics (variance and kurtosis), and closed form Bit-Error-Probability (BEP) analytic expressions. Numerical results on the obtained BEP after Reed-Solomon coding evidence that, when randomly selected, De Bruijn sequences perform very close to Gold sequences having the same length. The performance provided by De Bruijn sequences get remarkably better than the Gold ones when a proper selection procedure, aimed at minimizing the pairwise aperiodic cross-correlation, is adopted. The selection procedure and the corresponding results are discussed in details within the paper
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