In VANETs we read a lot about classifying the packets arriving at vehicles as being either arrived from "vehicles at the front" or from "vehicles at the back". However, I am interested to know about the theory behind the detection of a signal's direction of arrival in VANETs. What equipment is used in that? Do positioning devices such as GPS or GNSS modules play a major role, and what is the theory behind it?
It depends on the VANET routing protocol. If neighbour information includes position, then it is straightforward to determine the direction of arrival. If not, then you would need to use some sort of physical-layer angle-of-arrival determination method, which is essentially an inverse-beamforming problem (measuring the phase relation between signals received at different elements of an antenna array). It is non-trivial and for most VANET routing protocols, not really necessary (as signal propagation environment is somewhat constrained anyway).
Thank you Daniel. You are right, with the inclusion of positioning support using GPS or GNSS enabled modules, we should be able to find the vehicles absolute position, direction of vehicles movement, speed (In stand alone mode, i.e. in each car).
If the positions are shred among vehicles, then distance between them can be found as well. However, i think GIS maps (along with parameters mentioned above) would also play a role in finding the relative position of vehicle from one another in a specific road segment.
Regards,
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