Comparison of Performance between AND and Majority Logic Type Nonlinear Feedforward Logic Pseudonoise Sequence Generators

Two classes of nonlinear feedforward logic (NLFFL) pseudonoise (PN) code generators based on the use of AND and majority logic (ML) gates are compared. Crosscorrelation and code-division multiple-access (CDMA) properties of properly designed NLFFL sequences are found to be comparable with the properties of well-known linear PN codes. It is determined that code design employing ML gates with an odd number of inputs is easier compared with designing with AND gates. This is especially true when the degree of nonlinearity is large, since the nonbalance problem, e.g., at the output of an AND gate, can be avoided. ML type sequences are less vulnerable to correlation attack and jamming by the m-sequence of an NLFFL generator key words: information security, spreading code, stream cipher, linear complexity, correlation attack, spread-spectrum system, code-division multiple-access