A the central computer transmitted and the terminals received. If two stations sent something at the same time, the messages would collide and nothing would be received correctly by the central receiver. If a node didn t get an acknowledgement, it sent it again after a random wait. If you were the only person using the network at the time, the Aloha system works very well. Your terminal can send data whenever it needs to and it can use the full capacity of the channel.
Problems arise when the network gets busy.
As more and more users are sending data, some of the transmissions overlap and are not properly received by the central computer. When the system is very lightly loaded, more transmissions result in more data being received by the central computer. At some point more transmissions just increases the likelihood of a collision. The more transmissions that are sent, the more collisions occur and the less data that actually reaches the destination. Here we will determine how much data we can send through an Aloha network.