Is the Brownian bridge a good noise model on the boundary of a circle?
  In this paper we study periodical stochastic processes, and we define the conditions that are needed by a model to be a good noise model on the circumference. The classes of processes that fit the required conditions are studied together with their expansion in random Fourier series in order to provide results about their path regularity. Finally, we discuss a simple and flexible parametric model with prescribed regularity that is used in applications, and we prove the asymptotic properties of the maximum likelihood estimates of model parameters. 
Giacomo Aletti and Matteo Ruffini
math.PR math.ST stat.TH