Wired Transmission Media
Copper (Twisted Pair) Cable
The most common wired medium in LANs. Pairs of copper wires twisted together to reduce interference (electromagnetic interference/EMI). Used in Ethernet connections (Cat5e, Cat6, Cat7).
- Speeds: up to 10 Gbps (Cat7)
- Low cost, easy to install
- Susceptible to EMI over long distances; signal degrades after ~100 m
Fibre Optic Cable
Uses pulses of light along a glass or plastic fibre core to transmit data. Not affected by electromagnetic interference.
- Extremely fast — up to hundreds of Gbps
- Very long range — signal travels much further without degradation
- More expensive to install than copper
- Used in broadband internet backbones and high-speed LANs
Wireless Transmission
Wi-Fi (IEEE 802.11)
Uses radio waves to transmit data wirelessly. Devices connect to a Wireless Access Point (WAP) which links to the wired network.
- Convenient — no cables required; supports mobile devices
- Speed affected by distance from WAP, walls, and interference
- Less secure than wired — signals can be intercepted unless encrypted (WPA2/WPA3)
- Range: typically up to ~50 m indoors
Bluetooth
Short-range wireless technology using radio waves. Designed for device-to-device communication (PAN — Personal Area Network).
- Range: typically up to ~10 m
- Lower power consumption than Wi-Fi
- Used for: wireless headphones, keyboards, mice, file transfer between nearby devices
- Slower than Wi-Fi
Comparison Table
| Medium | Speed | Range | Security | Cost | Use case |
|---|
| Copper cable | High (up to 10 Gbps) | ~100 m | Good | Low | Office/school LAN |
| Fibre optic | Very high (100+ Gbps) | Very long | Very good | High | ISP backbone, high-speed LAN |
| Wi-Fi | Moderate–high | ~50 m indoors | Less secure | Low | Mobile devices, homes |
| Bluetooth | Low | ~10 m | Moderate | Very low | Peripherals, PAN |
Factors Affecting Network Performance
- Bandwidth — the maximum amount of data that can be transmitted per second (bits/s)
- Latency — the delay between sending and receiving data (ms); affects real-time applications
- Interference — wireless signals disrupted by other devices, walls, or distance
- Number of users — more users sharing a connection reduces available bandwidth per user
- Transmission medium — fibre is faster and more reliable than copper
📝 Exam Tip: When comparing wired vs wireless, key points are: wired = faster, more secure, less flexible; wireless = convenient, portable, but slower, shorter range, and less secure. Fibre optic beats copper on speed and range but at higher cost.
⚠️ Common Mistakes
- Saying Wi-Fi "uses the internet" — Wi-Fi is a way of connecting to a network; the internet is a separate concept
- Forgetting that wireless is less secure — signals can be intercepted unless encrypted
- Confusing bandwidth with speed — bandwidth is capacity; actual speed depends on multiple factors