As road networks are the backbone of transportation and personal mobility, congestions are a severe problem. Improving the utilization of existing roads by scheduling shared resources, e.g. crossroads; more efficiently is a promising approach to alleviate the problem. We have developed an architecture allowing mobile systems to schedule shared resource in real-time based on wireless communication. In this paper, we present two membership protocols, which are at the core of this architecture. The protocols allow mobile systems to join and leave a group with predictable delay. A synchronous system model with omission failures describes the dynamic properties of the medium. The protocols exploit application knowledge to allocate bandwidth to joining stations dynamically yet predictably. Nevertheless, they can be converted to a general solution if predictable join delays are not a requirement.