Fiber-optic cables transmit data as light, twisted-pair cables use electrical signals, and wireless systems use electromagnetic waves through the air. Fiber optic generally provides the greatest bandwidth and resistance to interference; twisted pair is inexpensive and practical; wireless enables mobility but is more affected by interference and security risks.
How Each Transmission Medium Works
A transmission medium is the channel through which data travels between devices. Fiber optic and twisted pair are guided media, because signals follow a physical cable. Wireless is an unguided medium, because signals propagate through the air.
| Medium | Mechanism | Main advantages and limitations |
|---|---|---|
| Fiber optic | Pulses of light travel through thin glass or plastic fibers. | Very high bandwidth, low attenuation over long distances, and immunity to electromagnetic interference. Installation and repair can be expensive, and the cable requires careful handling. |
| Twisted pair | Electrical signals travel through pairs of insulated copper wires. Twisting reduces electromagnetic interference and crosstalk. | Inexpensive, widely available, and easy to install. It normally has lower bandwidth and greater attenuation than fiber optic and remains more vulnerable to interference. |
| Wireless | Data is carried by electromagnetic waves, such as radio or microwave signals. | Supports mobility and avoids physical cabling. Performance can vary because of distance, obstacles, congestion, and interference. Signals may also be intercepted, so encryption and authentication are important. |
The best medium depends on the network's requirements. A data center may use fiber optic for high-speed backbone connections, an office may use twisted-pair Ethernet for individual computers, and mobile devices may use wireless networking for convenient access.
A common misconception is that wireless is always faster because it is newer. In practice, speed depends on the technology, environment, bandwidth, and network congestion; wired fiber connections generally offer greater capacity and consistency.
IB Exam Technique
For A2.3 Data transmissions, compare media using named criteria: signal type, bandwidth, attenuation, interference, security, mobility, distance, and cost. For an “evaluate” question, connect each advantage or limitation to the stated scenario before reaching a justified conclusion.
