The design of a collision avoidance system for trains
implies the design of a MAC layer for their specific requirements.
It should be efficient, reliable, use broadcast and support wireless
mobile ad hoc networks (MANETs) with high user speeds.
Therefore we are using awareness techniques, which allow a
certain channel assignment, despite the absence of infrastructure.
This paper presents a new MAC layer protocol designed for
broadcast MANETs called COMB (Cell-based Orientation-aware
MANET Broadcast). In principle, COMB allows the realization
of a collision free transmission, high speed is supported and no
handshake is required. COMB is based on localization aware
cross layer dimensioned CDMA cells, and uses the SOTDMA
protocol as intra cell scheme, while the inter cell scheme relies
on direction and speed awareness
