The rules of ALOHA :There are two types of ALOHA rules :
1) Multiple Access
2) Acknowledgement
Any section sends a frame when. It has a frame send, the frame the section wait for.
After sending an acknowledgement(explicit/implicit). It does not receive an acknowledgement during. The allocated time which is 2 times the maximum propagation-delay.The time it takes for the first bit of the frame to reach every station, It assigns that the frame is lest, It tries sending again after a random amount of time.