Slotted aloha Assumptions Operation o All frames same size o when node obtains fresh o Time is divided into equal frame, it transmits in next size slots time to transmit slot 1 frame o no collision, node can send o Nodes start to transmit new frame in next slot frames only at beginning If collision, node retransmits of slots frame in each subsequent o Nodes are synchronized slot with prob. p until o If2 or more nodes success transmit in slot all nodes detect collision 5: DatSlotted ALOHA Assumptions  All frames same size  Time is divided into equal size slots, time to transmit 1 frame  Nodes start to transmit frames only at beginning of slots  Nodes are synchronized  If 2 or more nodes transmit in slot, all nodes detect collision Operation  When node obtains fresh frame, it transmits in next slot  No collision, node can send new frame in next slot  If collision, node retransmits frame in each subsequent slot with prob. p until success 5: DataLink Layer 5-16