CSMA/CD
The CSMA/CD relies on sensing the channel and transmit only when the channel il free
flowchart TD A{channel is\n free} B[send message] C{collision\n detected} D[wait a random time] A-->|yes|B B-->C C-->|yes|D A-->|no|D D-->A
In wireless environment this approach have some issues due to the nature of the nodes not being able to listen the entire channel and the node mobility
HIDDEN AND EXPOSED NODE ISSUES
This are particular problems that can manifest in a wireless environment
CSMA/CA VARIANT
A way to limit the hidden/expose node issue is to send short acknowledgement frames before transmit:
flowchart TD A[A] B[B] A --sends rts--> B B --sends cts--> A
so the node A sends a request to send packet to B and wait for a clear to send reply before start transmitting the data
this solution limits collisions only to the rts and cts packets reducing the cost of re transmission but increase the overhead because every communication requires an rtc/cts exchange