De Bruijn sequences for secure scrambling at Long Term Evolution - Advanced physical layer

The intent of the paper is to propose a new set of scrambling codes to spread information in a manner that provides superior physical layer security. In wireless communication systems, physical layer elements are vulnerable to possible security-related attacks by undesired entities. Basic premise of a reliable communication infrastructure is to mitigate risks related to violations of the user information integrity, authenticity, and to provide efficient control and management information flow. The 3GPP Long Term Evolution - Advanced achieves this goal by using robust scrambling technique for control channel information, by means of binary Gold sequences used as scrambling codes. Gold sequences provide good correlation-related properties, however they have been known for a long time, thus they are weak in security-related features, starting from their very limited cardinality. This paper suggests the use of De Bruijn sequences as the next generation set of scrambling codes, for their huge cardinality and satisfactory correlation-related properties. Different spans of De Bruijn codes are analyzed to examine their performance, with a specific emphasis on sequences of length 32, that are comparable to the Gold codes currently suggested by the standard. De Bruijn sequences are seen to provide much more favorable results, even with respect to security-related tests.