In the Korean city of Suvon, there is an ancient fortress. Among its fortifications, a high massive construction crowned with five cylindrical towers comes under one's notice. What is that?
Timely warning of enemy's invasion was an important problem for any state. In Russia, there was a system of outposts. The distance between outposts could be covered by a rider without rest. There was a fresh horse at call at every outpost. To the order of a commandant, a staffette started out. He changed horses at outposts and rode hard until he reached his destination. The speed of communication depended only on the horse's speed.

A faster system of signalling existed in ancient Korea. The entire country was covered with a network of fortresses with signal towers. Luckily Korea is a mountainous country so it was not difficult to find a high ground seen from a great distance. In case of invasion, the fortress garrison stood on the defensive, and fires were immediately laid in all five towers. The observers from neighboring fortresses saw the five fires and immediately gave the alert and laid four fires in four towers. The signal was extremely easy to decode:

Fire fires meant “Invasion, fighting a battle”.
Four fires meant “Enemy in neighboring fortress”.
Three fires meant “Enemy two towers away from me” and so on.

Less than two hours later, the message sent from the boundary port of Pusan reached Seul after covering 400 km. High speed of communication made ample amends for information scarcity.
In TRIZ this principle is called “Segmentation”. The entire territory of the country was divided into sections within which a maximally fast communication was provided.