Asymptotic property of the occupation measures in a two-dimensional skip-free Markov modulated random walk

TL;DR

This paper analyzes the asymptotic decay of occupation measures in a two-dimensional skip-free Markov modulated random walk, providing insights into their behavior at infinity and the convergence domain of their generating functions.

Contribution

It introduces the asymptotic analysis of occupation measures in a two-dimensional skip-free Markov modulated random walk, including decay rates and convergence domains.

Findings

Derived the asymptotic decay rate of occupation measures.

Identified the convergence domain of the matrix moment generating function.

Provided theoretical results on occupation measure behavior at infinity.

Abstract

We consider a discrete-time two-dimensional process $\{(X_{1,n},X_{2,n})\}$ on $\mathbb{Z}^2$ with a background process $\{J_n\}$ on a finite set $S_0$, where individual processes $\{X_{1,n}\}$ and $\{X_{2,n}\}$ are both skip free. We assume that the joint process $\{\boldsymbol{Y}_n\}=\{(X_{1,n},X_{2,n},J_n)\}$ is Markovian and that the transition probabilities of the two-dimensional process $\{(X_{1,n},X_{2,n})\}$ vary according to the state of the background process $\{J_n\}$. This modulation is assumed to be space homogeneous. We refer to this process as a two-dimensional skip-free Markov modulate random walk. For $\boldsymbol{Y}, \boldsymbol{Y}'\in \mathbb{Z}_+^2\times S_0$, consider the process $\{\boldsymbol{Y}_n\}_{n\ge 0}$ starting from the state $\boldsymbol{Y}$ and let $\tilde{q}_{\boldsymbol{Y},\boldsymbol{Y}'}$ be the expected number of visits to the state $\boldsymbol{Y}'$ before the process leaves the nonnegative area $\mathbb{Z}_+^2\times S_0$ for the first time. For $\boldsymbol{Y}=(x_1,x_2,j)\in \mathbb{Z}_+^2\times S_0$, the measure $(\tilde{q}_{\boldsymbol{Y},\boldsymbol{Y}'}; \boldsymbol{Y}'=(x_1',x_2',j')\in \mathbb{Z}_+^2\times S_0)$ is called an occupation measure. Our main aim is to obtain asymptotic decay rate of the occupation measure as the values of $x_1'$ and $x_2'$ go to infinity in a given direction. We also obtain the convergence domain of the matrix moment generating function of the occupation measures.