Smart error-control strategy for low-power communication in wireless networked control system

摘要

We consider a Wireless Networked Control System (WNCS) in an indoor environment and discuss the impact of wireless channel characteristics on the stability and performance of wireless feedback control-loop system. The presence of mobile/static obstacles and other radio interferences in indoor space causes random transmission errors and therefore, it becomes challenging to establish timely and reliable communication among distributed WNCS nodes (sensor, controller and actuator). To overcome communication errors in an energy-efficient way, we propose a novel Forward Error Correction (FEC) based smart error control mechanism which at its core employs a cascaded fuzzy inference system. The proposed strategy unifies three heterogeneous metrics, e.g. Signal-to-Noise Ratio, Line-of-Sight/Non-Line-of-Sight detection and packet ACK/NACK information, to accurately estimate the radio links quality and to select an appropriate error correction code. The performance of the proposed approach have been evaluated in simulated environment that includes realistic indoor fading channel model and IEEE 802.15.4 2.4 GHz modulation format for the network nodes. Based on obtained results, we conclude that the proposed smart error control scheme not only offers better trade-off in terms of packet error rate and energy efficiency as compared to static FEC codes and IEEE802.15.4 ARQ (Automatic Repeat-reQuest) mechanism, but also achieves increased stability of WNCS.