We consider teams of mobile autonomous robot systems that coordinate their work via communication over a wireless local area network. In such a scenario, timely delivery and group support are the predominant requirements on the communication protocol. As the mobile robot systems are communicating via standard hardware, we base our work on the IEEE 802.11 standard for wireless local area networks. In this paper, we present a reliable real-time group communication protocol that enhances the IEEE 802.11 standard. The reliability and real-time properties of the protocol are based on time-bounded dynamic time redundancy. By this, network bandwidth is used much more efficiently than in a message diffusion approach based on static redundancy. The fault detection mechanism needed to implement the timebounded dynamic redundancy concept is achieved by an implicit acknowledgement scheme that consumes no additional bandwidth for acknowledgement messages.