I did a project before. The main reason is because the remote
control car communicates with the remote control in bits via
wireless. However, to confirm that the signal received is indeed
from the correct remote control, there are certain set
authentications between them. Only when the authentication signal
is authenticated is the resulting information processed, and the
car moves according to the information. However, there are presence
of random signals in the air, and there's always a probability of a
random signal giving the right authentication.
A mathematical example:
Supposed 8 bits were used as authentication. There will be 2^8 =
256 possible authentications... Which means there is a 1/256 chance
of a random signal being able to authenticate with the car, and
thus causing the car to move randomly.
Supposed 16 bits, there will be 2^16 = 65536 possibilities.
A better algorithm would be to include a Cyclic Redundancy Check.
This further increases the number of possibilities, which will in
turn reduce the probability of a random authenticated signal.
Sorry for the brief explanation... I didn't specialise into
infocomm technologies, but hope you get the rough idea.
