The Periods of a Class of Nonlinear Feedback Shift Register Sequences

In this paper, we discuss a class of n-stage Nonlinear feedback shift registers (NFSRs). Applying the knowledge of algebra, the least periods of the sequences generated by these NFSRs with symmetric feedback functions can be characterized. This approach simplifies the problem of determining the periods of the NFSR sequences and it generalizes some Cheng's results.