title: Networked estimation for event-based sampling systems with packet dropouts.
abstract: This paper is concerned with a networked estimation problem in which sensor data are transmitted over the network. In the event-based sampling scheme known as level-crossing or send-on-delta (SOD), sensor data are transmitted to the estimator node if the difference between the current sensor value and the last transmitted one is greater than a given threshold. Event-based sampling has been shown to be more efficient than the time-triggered one in some situations, especially in network bandwidth improvement. However, it cannot detect packet dropout situations because data transmission and reception do not use a periodical time-stamp mechanism as found in time-triggered sampling systems. Motivated by this issue, we propose a modified event-based sampling scheme called modified SOD in which sensor data are sent when either the change of sensor output exceeds a given threshold or the time elapses more than a given interval. Through simulation results, we show that the proposed modified SOD sampling significantly improves estimation performance when packet dropouts happen.
authors.affiliation: Department of Electrical Engineering, University of Ulsan, Namgu, Ulsan 680-749, Korea; E-Mail:  vinhhao@hcmut.edu.vn  (V.H.N.).
authors.forename: Vinh Hao
authors.initials: VH
authors.lastname: Nguyen
authors.forename: Young Soo
authors.initials: YS
authors.lastname: Suh