A note on adaptive coding scheme based on control quality for wireless feedback control systems

Packet loss is the major weakness of wireless feedback control systems. In this paper, we discuss the improvement of the control quality of wireless feedback control systems with Forward Error Correction (FEC) coding. If FEC coding is used, packet losses may decrease. But its redundancy decreases the packet transmission rate under the same bit rate, so that the control quality will be worse. Therefore, we propose an adaptive coding scheme to improve the control quality. In this scheme, FEC coding is used adaptively based on a predicted state of the controlled plant. Our proposal is the first approach in the field of adaptive channel coding for wireless feedback control systems because this scheme adapts channel coding to the quality of the control layer (application layer). In this paper, we show that the proposed adaptive coding scheme improves the control quality more than that of the fixed rate coding in Rayleigh fading channels.