A note on adaptive coding scheme for improvement of reference tracking in wireless feedback control systems

In wireless feedback control systems, it is important how to reduce packet losses. If channel coding is used, packet losses may decrease. But its redundancy decreases the packet transmission rate under the same bit rate, so that disturbances in the controlled plant may deteriorate the quality of the control system. To improve the quality of the control system, the channel coding should be used adaptively based on packet losses and disturbances. In this paper, we propose an adaptive coding scheme based on the quality of the communication layer and the control (application) layer. In this scheme, the channel coding is used adaptively based on a predicted state of the controlled plant under a packet loss rate. We show that the proposed adaptive coding improves the control quality compared with that of the fixed rate coding.