Non- and p-persistent CSMA Protocols

In non-persistent and p-persistent protocols, each station may again sense a busy channel.

If the channel is found too busy, contending stations 'back-off' for various intervals.

• Non-persistent stations back-off for random intervals.
• p-persistent stations 'jump in' with a probability p (or back-off for a constant amount of time with a probability q=1-p

Obviously, the lower the value of p the fewer collisions there will be (each station is almost 'chicken' to transmit).

Even though the channel utilization can approach its maximum, each station can be waiting a long time.