Learn in the textbookNetwork Classification and the Physical Foundation of Wired Connections
DefinitionA transmission path (伝送路) is the route a signal actually travels from sender to receiver, covering both wired media such as wiring and the space radio waves pass through.
ExplanationThe speed of a transmission path is expressed as its transmission speed (伝送速度, in bps), the number of bits it can send per second. Since control data and the like also flow over the path, the share of the transmission speed that can carry user data is called the transmission efficiency (伝送効率).
AnalogyIf the number of vehicles a road can pass per hour is the transmission speed, the share of them that are trucks carrying cargo is the transmission efficiency. The rest are escort vehicles that manage traffic and carry no cargo.