About the Use of a New Set of Quadriphase Sequences for Increasing Security of PMR over LTE Primary Synchronization

Current 4G mobile communication systems are relying on LTE standard and on its evolution, namely LTE-A. Thanks to its widespread diffusion and to the capability of efficiently supporting broadband multimedia data exchange, LTE considers some particular extensions of the standard for private mobile radio (PMR) networks in the framework of public security communications. Unfortunately, some open issues of LTE in terms of vulnerability to security attacks may hinder such kind of safety-critical applications. In this paper, we propose a novel solution to one of these issues, namely the primary synchronization signal (PSS) spoofing, based on a new set of quadriphase sequences: the Even-Odd-Equivalent (EOE) pseudo De Bruijn (DB) sequences, obtained by a simple transformation of binary De Bruijn sets. EOE pseudo DB sets are characterized by equal even and odd crosscorrelation, near-impulsive autocorrelation and very large cardinality. This last feature makes the use of EOE pseudo DB sets an efficient countermeasure against PSS spoofing. As compared with the standard solution based on the use of Constant-Amplitude Zero Autocorrelation (CAZAC) Frank-Zadoff-Chu (FZC) sequences, the proposed solution increases the PSS robustness against spoofing attacks, performing very close to FZC in terms of cell ID detection probability.