Design of a Reliable Communication System for Grid-Style Traffic Light Networks

This paper presents the design and analyzes the performance of a reliable communication scheme for the traffic control system built upon a wireless process control protocol, aiming at enhancing the robustness and timeliness of the safety-critical control applications. By exploiting the slot-based predictable access and the grid topology of urban area road networks, the proposed scheme establishes one primary and secondary route from the controller to each node and allocates the time slots accordingly. This is facilitated by a split-merge operation that makes a sender node sense the primary channel(channel to the primary receiver) and take the secondary channel only if the first one is not free in a single slot, while making the receiver first listen to the primary sender and switch to the secondary sender. Our scheme also finds the path with the lowest error rate by modeling the split-merge operation as a single virtual link and applying shortest path algorithm. The experimental results show that the proposed scheme greatly enhances the transmission success ratio for the grid-style traffic control network and the improvement scales up with the network size. In addition, the routing scheme can further find the path that can improve the delivery ratio of control messages compared with the traditional grid routing scheme.