(From the Hawaiian greeting) A system of contention resolution devised at The university of hawaii. packets are broadcast when ready, the sender listens to see if they collide and if so re-transmits after a random time. slotted aloha constrains packets to start at the beginning of a time slot. Basic Aloha is appropriate to long propagation time nets (e.g. satellite). For shorter propagation times, carrier sense protocols are possible.