I do not remember exactly but I would try, It might
be that because the medium have a finite transmission
time. Any node will be listening and start transmission
when there is not one else transmitting. If a collision
is detected the node will go to listening for a random
period of time. After that will transmit again but if the
distance is too much it will not be able to know the
exact time for a collision and may never be able to
transmit.