Electron. J. Differential Equations, Vol. 2026 (2026), No. 41, pp. 1-20.

Least squares estimation for sub-fractional Brownian bridge with linear drift

Nenghui Kuang, Huantian Xie

Abstract:
In this article we consider least squares estimation (LSE) for sub-fractional Brownian bridge with linear drift defined by $$ dX_t=\frac{\alpha (k-X_t)}{T-t}dt+dS^{H}_t, \quad 0\leq t< T,\quad X_0=x_0, $$ where \(\alpha>0\), \(k\in R\) and \(\tau:=\alpha k\) are unknown parameters, and \(S^{H}\) is a sub-fractional Brownian with Hurst index \(H\in (1/2, 1)\). We prove that the LSE has strong consistency as \(t\to T\) depending on the value of \(\alpha\). When it has consistency, we obtain the rate of this convergence. This work extends the results by Kuang and Liu [11] who studied the case \(k=0\) and \(x_0=0\).

Submitted September 25, 2025. Published June 11, 2026.
Math Subject Classifications: 60G15, 60H05, 62F12.
Key Words: Least squares estimation; sub-fractional Brownian bridge; strong consistency.
DOI: 10.58997/ejde.2026.41

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Nenghui Kuang
School of Mathematics and Statistics
Hunan University of Science and Technology
Xiangtan, Hunan 411201, China
email: knh1552@163.com
Huantian Xie
School of Mathematics and Statistics
Linyi University
Linyi, Shandong 276005, China
email: xiehuantian@lyu.edu.cn

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