A local limit theorem for lattice oscillating random walks

Abstract

In this paper, we obtain a local limit theorem for the Kemperman's model of oscillating random walk on $\mathbb{Z}$; it extends the existing results for classical random walks on $\mathbb Z$ or reflected random walks on $\mathbb N_0$. The key technical point is to control the long-term behavior of the embedding subprocess that characterizes the oscillations of the original random walk between $\mathbb Z^-$ and $\mathbb Z^+$ in both recurrent and transient cases. Then by combining an extension of \cite[Theorem 1.4]{gouezel} for the convergence of aperiodic sequence of renewal operators acting on a suitable functional Banach space and the decomposition of the trajectories of the random walk, we obtain the exact asymptotic for the return probability under some mild assumptions on the increment moments.