Spec & Goals 3 min
AQA Spec 3.5.1.1 — Wired vs wireless networks; factors affecting network performance
By the end of this lesson you can:
- Describe the difference between a wired and a wireless network.
- Give advantages and disadvantages of wireless compared with wired.
- List the factors that affect the performance of a network.
Warm-Up 5 min
Last lesson you sorted networks by size (PAN, LAN, WAN). Now we sort by how the signal travels: through a cable, or through the air.
Quick starter
Your home router has a socket for a cable and broadcasts Wi-Fi. Which would you choose for a gaming PC, and which for a phone? Why?
Reveal the idea
Cable (wired) for the gaming PC — faster and more reliable, no interference. Wi-Fi (wireless) for the phone — you want to carry it around. That trade-off is the whole lesson.
Key Concept — cables vs the air 14 min
A wired network connects devices with physical cables (usually copper Ethernet, or fibre-optic). A wireless network connects them using radio waves — most commonly Wi-Fi, or Bluetooth for a PAN.
Wireless — advantages vs a wired network
- Mobility — move around freely while staying connected.
- No cabling — cheaper and tidier to install; no trailing wires.
- Easy to add devices — just connect to the network name.
Wireless — disadvantages vs a wired network
- Slower and lower bandwidth than a good wired link.
- Less reliable — signal weakens with distance and through walls; suffers interference.
- Less secure — radio waves travel beyond the building, so signals can be intercepted (encryption is essential — Lesson 9).
Factors that affect network performance
"Performance" usually means how fast data moves and how reliably. AQA expects these factors:
| Factor | Effect on performance |
|---|---|
| Bandwidth | The amount of data the link can carry per second. More bandwidth → faster. |
| Number of users / devices | Many users sharing a link slows it for everyone (contention). |
| Transmission medium | Fibre is faster and less error-prone than copper; copper beats wireless. |
| Interference (wireless) | Walls, distance and other devices weaken a Wi-Fi signal. |
| Latency | The delay before data starts arriving; high latency feels "laggy". |
Worked Example — choosing a connection 12 min
Problem: A library in Ipoh is fitting out a new study room. Recommend wired or wireless for (a) 20 fixed desktop PCs and (b) visitors' phones and laptops. Justify each choice.
(a) The 20 desktops — wired (Ethernet).
- They never move, so mobility is not needed.
- Wired gives higher, more reliable bandwidth for 20 machines at once.
- Cables are more secure — signals can't be picked up outside the room.
(b) Visitors' devices — wireless (Wi-Fi).
- Visitors bring their own devices and move around — they need mobility.
- No need to run a cable to every seat; cheaper and tidier.
- Accept lower speed and add encryption for security.
Try It Yourself 12 min
Goal: State what carries the signal in (a) a wired and (b) a wireless network.
Hint: cable vs radio waves.
Goal: Give two advantages and two disadvantages of a wireless network compared with a wired one.
Goal: A café's Wi-Fi slows down at lunchtime. List three factors that could explain it and say how each affects performance.
Hint: think users, interference and bandwidth.
📝 Exam Practice 10 min
State what is used to carry data in a wireless network.
Mark scheme
- Radio waves (accept: Wi-Fi / electromagnetic / microwave signals) (1).
A school is deciding between a wired and a wireless network for its classrooms. Discuss the advantages and disadvantages of each.
Mark scheme
Up to 4 marks for balanced points, e.g.:
- Wired — faster / more reliable / more secure (1); but costly to cable / not portable (1).
- Wireless — portable / cheaper to install / easy to add devices (1); but slower / interference / less secure (1).
Explain how the number of users can affect the performance of a network.
Mark scheme
- The available bandwidth is shared between users (1).
- So more users → less bandwidth each → the network slows down / is contended (1).
Recap & Key Terms 3 min
A wired network sends data down cables; a wireless network uses radio waves (Wi-Fi). Wired is faster, more reliable and more secure; wireless is portable and cheaper to install. Performance depends on bandwidth, number of users, the transmission medium, interference and latency.
- Wired network
- Devices connected by physical cables (e.g. Ethernet) to carry the signal.
- Wireless network
- Devices connected using radio waves (e.g. Wi-Fi) instead of cables.
- Bandwidth
- The maximum amount of data a connection can transmit per second (bits per second).
- Latency
- The delay before data begins to arrive across a network.
Homework 1 min
Task (≤ 15 min): Hafiz says "wireless is always better than wired". Write a short paragraph (3–4 sentences) explaining why this is not always true, using at least two factors that affect performance.
Model answer
Wireless is convenient and portable, but a wired link usually has higher bandwidth and lower error rates, so it is faster and more reliable. Wireless suffers interference from walls and distance, and as the number of users rises the shared signal slows down. Wired is also more secure because the signal stays in the cable. So "always better" is wrong — it depends on the need.
Award marks for: stating wireless is not always better (1); two valid factors used correctly (2).