Vehicular Ad-hoc Networks (VANETs) have a significant
potential to enable new applications among multiple types
of vehicles. In these networks, the Medium Access Control (MAC)
plays an important role in providing an efficient communication
channel. Currently, existing standards use the PHY and MAC of
IEEE 802.11p, which is fully distributed and based on Carrier
Sense Multiple Access with collision Avoidance (CSMA/CA), thus
still prone to collisions. This has led to recent proposals for
TDMA-based overlay protocols to prevent collisions, including
one based on Reconfigurable and Adaptive TDMA (RA-TDMA).
This protocol sets a TDMA round allocating slots to the nodes
engaged in a given collaborative application, only, e.g., a platoon
or a multimedia group. Then, other traffic, including from
other TDMA rounds of concurrent applications can co-exist
in space and time using the native CSMA/CA mechanism of
IEEE 802.11p and the synchronization mechanism of RA-TDMA.
In this paper, we do a qualitative comparison among TDMA
protocols in VANETs showing the advantages of RA-TDMA.
Early experimental results validate the capacity of RA-TDMA
to support multiple concurrent rounds in a scalable manner.