Signals, Media & Bandwidth
Choose an appropriate medium and distinguish throughput from capacity.
How bits travel
Copper carries electrical signals, fiber carries light, and wireless links carry radio signals. Each medium has limits involving range, interference, cost and achievable rate. A wired Ethernet link is usually stable; Wi-Fi allows mobility but shares airtime with other devices.
A repeater or access point can extend local coverage but does not by itself remove an upstream bottleneck.
Rate, throughput and latency
Link rate is the nominal number of bits a link can transmit per second. Throughput is the useful data delivered over time and can be lower because of headers, competing traffic, errors and retransmissions. The slowest constrained link on a path often limits end-to-end throughput.
A 100 Mbps access link cannot produce 100 Mbps end-to-end when an upstream path permits only 20 Mbps.
Check your understanding
A path has 100 Mbps, 10 Mbps and 50 Mbps links. What is its ideal bottleneck rate?