On hold or drop out-of-order packets in networked control systems

Holding or dropping out-of-order packets in the communications are two typical signal choosing schemes in networked control systems. However, neither of the two schemes can be claimed always superior to the other. To improve the control performance, a smart signal choosing scheme is proposed to determine whether to use the out-of-order packets. It is theoretically proved that improved performance can be obtained based on the proposed smart signal choosing scheme. Two numerical examples are given to demonstrate the effectiveness of the proposed approach.