  As the domain of cyber-physical systems continues to grow, an increasing
number of tightly-coupled distributed applications will be implemented on top
of wireless networking technologies. Some of these applications, including
collaborative robotic teams, work in a coordinated fashion, whereby a
distinguished node takes control decisions and sends commands to other nodes,
which in turn perform the requested action/operation and send back a
reply/acknowledgment. The implementation of such interactions via reliable
point-to-point flows may lead to a significant performance degradation due to
collisions, especially when the system operates close to the capacity of the
communication channel. We propose a coordinated protocol which exploits the
broadcast nature of the wireless medium in order to support this
application-level interaction with a minimal number of message transmissions
and predictable latency. The protocol also comes with group management
functionality, allowing new processes to join and existing processes to leave
the group in a controlled way. We evaluate a prototype implementation over
WiFi, using a simulated setup as well as a physical testbed. Our results show
that the proposed protocol can achieve significantly better performance
compared to point-to- point approaches, and remains fully predictable and
dependable even when operating close to the wireless channel capacity.
