I. Introduction
Event-triggered control (ETC) pertains to strategies that manage transmissions in a control loop based on events rather than time and it is intended for control applications where communication resources are scarce or costly. Extensive research has been carried out in the past decade on ETC, mostly focusing on a single control loop closed over a single communication channel [1]–[5]. However, communication management is especially interesting in settings where the communication network is shared by multiple control loops [6]–[8], as illustrated in Fig. 1. Contention-free protocols such as time-division multiple access (TDMA) [9] enable periodic transmission for all the control loops but lead to inefficient bandwidth usage when some of the control loops alternate between being active and inactive. In fact, under these conditions, systems operating through these protocols need a central coordinator for the reallocation of communication resources to different users, hence scalability is an issue for these medium access control protocols. In turn, contention-based protocols such as slotted-ALOHA [9] can be reconfigurable in a decentralized manner. However, contention in these protocols could hamper the control design and analysis, when the loops transmit based on events. In fact, if event-based data triggering is influenced by the states of the systems and the control inputs, then due to network contention, every local optimal controller depends on the state of all network dynamic users and this hampers decentralization when designing the control and scheduling laws.