Wireless network design for distributed control

We present a cross-layer framework for the joint design of wireless networks and distributed controllers. The design objective is to optimize the control performance. This control performance is a complex function of the network parameters, such as throughput, packet delay and packet loss probabilities. The goal of optimizing the control performance imposes implicit tradeoffs on the wireless network design as opposed to the explicit tradeoffs typical in wireless data and voice applications. Specifically, the tradeoffs between network throughput, time delay and packet loss probability are intricate and implicit in the control performance index, which complicates network optimization. We show that this optimization requires a cross-layer design framework. We first present this framework for a broad class of distributed control applications. We then illustrate this framework by a cross-layer optimization of the link layer, MAC layer, and sample period selection in an inverted pendulum system. Our results indicate that cross-layer design significantly improves the performance and stability of the controller.