Final answer:
The slotted Aloha protocol improves network efficiency by dividing time into slots, allowing frames to be sent at the start of each slot and reducing collisions.
Step-by-step explanation:
The improvement that the slotted Aloha protocol provides over the original Aloha protocol is that it reduces the chance of collisions. This is achieved by dividing the time into equal-sized slots that are equivalent to the frame time. In slotted Aloha, nodes are only allowed to send data at the beginning of a time slot. This synchronization means that the overlaps of frames are reduced to the start of the next time slot, rather than at any random time, as in the original Aloha. Consequently, this improves the network throughput and efficiency because the protocol reduces the possibility of two frames colliding and allows more frames to be sent successfully without requiring retransmissions.