📁 Paper 2 · 3.5 Computer Networks
3.5e Wireless Networking
AQA 8525 · GCSE Computer Science · ~10 min read
Notes
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Worksheet
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Quiz

Wi-Fi Standards

Wi-Fi is based on the IEEE 802.11 family of standards. Each version has improved speed and range. The standard name tells you the generation.

StandardWi-Fi nameMax speedFrequencyNotes
802.11bWi-Fi 111 Mbps2.4 GHzLegacy
802.11gWi-Fi 354 Mbps2.4 GHzCommon legacy
802.11nWi-Fi 4600 Mbps2.4/5 GHzMIMO, widely used
802.11acWi-Fi 53.5 Gbps5 GHzMost common today
802.11axWi-Fi 69.6 Gbps2.4/5/6 GHzLatest — efficient in crowded areas

2.4 GHz band: longer range, penetrates walls better, but more crowded (used by microwaves, Bluetooth). 5 GHz band: faster, less interference, but shorter range and worse wall penetration. Wi-Fi 6: uses OFDMA and BSS colouring to handle many simultaneous connections efficiently — ideal for large venues like schools and airports.

Bluetooth

PAN technology

What is Bluetooth?

Short-range wireless standard for connecting personal devices. Uses the 2.4 GHz ISM band. Range ~10 m (Class 2). Low power consumption — ideal for battery-powered devices.

Common uses

Bluetooth applications

Wireless headphones/speakers, keyboard and mouse, phone-to-phone file transfer, smartwatches/fitness trackers, medical devices, car audio systems, IoT sensors.

Bluetooth vs Wi-Fi: Bluetooth is lower power and simpler to pair, but much shorter range and lower bandwidth. Wi-Fi is faster (streaming video) but uses more power. They operate on the same 2.4 GHz band and can interfere with each other.

Wi-Fi Security

Current standard

🔒 WPA2 / WPA3

WPA2 (Wi-Fi Protected Access 2) uses AES encryption — the current standard in most homes and businesses. WPA3 is the latest — stronger encryption, resistant to dictionary attacks, protects open networks with individual session encryption.

Network name

📡 SSID

Service Set Identifier — the name of the Wi-Fi network (e.g. "HomeNetwork_2.4G"). Hiding the SSID (disabling broadcast) provides minimal security through obscurity — attackers can still find hidden networks by scanning.

Access control

📋 MAC Address Filtering

Router only allows connections from devices with pre-approved MAC addresses. Adds a layer of access control. Not foolproof — MAC addresses can be spoofed (changed). Should be used alongside WPA2/WPA3, not instead of it.

Good practice

🔑 Strong Passwords

Default router passwords are a major vulnerability — change immediately. Use a long, random WPA2/WPA3 password. Regularly update firmware to patch security vulnerabilities in the router.

Risks of Unsecured Wi-Fi

⚠️ Open/unsecured Wi-Fi (e.g. free café Wi-Fi with no password) is a significant security risk:

• Packet sniffing: anyone on the same network can capture unencrypted data packets — login details, emails, web browsing
• Man-in-the-middle attacks: attacker intercepts traffic between your device and the router
• Evil twin / rogue hotspot: attacker sets up a fake Wi-Fi hotspot with the same name as a legitimate one to capture all traffic
• Mitigation: always use HTTPS websites, use a VPN on public Wi-Fi, avoid banking/sensitive transactions on open networks

Wired vs Wireless Comparison

FactorWired (Ethernet)Wireless (Wi-Fi)
SpeedUp to 10 Gbps (Ethernet)Up to 9.6 Gbps (Wi-Fi 6)
ReliabilityHigh — no signal interferenceSubject to interference and dead spots
SecurityMore secure — physical access neededLess secure — radio signals can be intercepted
MobilityNone — device must be cabledFull mobility within signal range
SetupRequires cables and portsEasy to connect without wiring
Best forDesktops, servers, gamingLaptops, phones, tablets, IoT
Exam tip: Know the Wi-Fi security protocols: WEP is old and broken; WPA2 is current standard; WPA3 is latest. For a question about improving Wi-Fi security, mention: use WPA2/WPA3 encryption, change default router password, disable unused features (WPS), and update firmware. SSID hiding and MAC filtering are weak measures on their own.
⚠️ Common Mistakes
  • Saying "Bluetooth uses the internet" — Bluetooth is a short-range PAN technology that connects devices directly. It does not use the internet or Wi-Fi.
  • Confusing WPA2 and WEP — WEP is old, cracked in minutes, and should never be used. WPA2 uses AES encryption and is the current standard.
  • Thinking hiding the SSID gives strong security — hiding the SSID only provides security through obscurity. Determined attackers can detect hidden networks. WPA2/WPA3 is the real protection.
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Key points

  • Wi-Fi standards: 802.11 family — Wi-Fi 4 (802.11n), Wi-Fi 5 (802.11ac), Wi-Fi 6 (802.11ax)
  • 2.4 GHz: longer range, more interference; 5 GHz: faster, shorter range
  • Bluetooth: PAN, ~10m, low power — headphones, keyboards, wearables
  • Wi-Fi security: WPA3 > WPA2 > WEP (broken); SSID hiding and MAC filtering are weak alone
  • Risks of open Wi-Fi: packet sniffing, MITM, evil twin hotspot; use HTTPS + VPN
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Worksheet — 3.5e Wireless Networking

8 questions · 19 marks

Q1What does IEEE 802.11 refer to, and what is Wi-Fi 6 also known as in this standard?[2]
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IEEE 802.11 is the family of wireless networking standards that define how Wi-Fi works [1]; Wi-Fi 6 is 802.11ax — the latest standard, capable of up to 9.6 Gbps, operating on 2.4/5/6 GHz bands, designed to be efficient in dense environments [1].
Q2Explain the difference between the 2.4 GHz and 5 GHz Wi-Fi bands.[2]
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2.4 GHz: longer range, better wall penetration, but more congested (shared with microwaves, Bluetooth, other Wi-Fi networks) [1]; 5 GHz: faster data transfer speed, less interference from other devices, but shorter range and does not penetrate walls as well [1].
Q3What type of network does Bluetooth create? Give two common uses of Bluetooth.[3]
✅ Mark scheme
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Bluetooth creates a PAN (Personal Area Network) [1]; common uses: any two from — wireless headphones/earbuds, wireless keyboard/mouse, smartwatch, file transfer between phones, car hands-free audio, fitness tracker, wireless speaker [2].
Q4What is WPA2, and why is it preferable to WEP for securing a Wi-Fi network?[2]
✅ Mark scheme
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WPA2 (Wi-Fi Protected Access 2) is a security protocol that uses AES encryption to protect Wi-Fi communications [1]; WEP (Wired Equivalent Privacy) is an older standard that has serious security vulnerabilities and can be cracked in minutes — WPA2 provides far stronger encryption that is not easily broken [1].
Q5What is an SSID? Does hiding it provide strong security? Justify your answer.[3]
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SSID (Service Set Identifier) is the name of a Wi-Fi network that appears in the list of available networks on a device [1]; hiding the SSID does NOT provide strong security [1]; although it is no longer visible in the list, the network still broadcasts its presence and attackers with appropriate tools can still detect the hidden network by capturing probe responses — it only provides security through obscurity [1].
Q6State two risks of using an unsecured public Wi-Fi network (e.g. in a café).[2]
✅ Mark scheme
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Any two: packet sniffing — others on the same network can intercept unencrypted data (passwords, emails) [1]; man-in-the-middle attack — attacker intercepts and potentially alters communications [1]; evil twin / rogue hotspot — attacker creates a fake network with the same name to capture all traffic [1].
Q7Give two advantages of wired networking over wireless networking.[2]
✅ Mark scheme
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Any two: more secure — physical access to the cable is needed to intercept data [1]; more reliable — no signal interference or dead spots, consistent connection [1]; potentially faster speeds at shorter distances [1].
Q8A school is setting up Wi-Fi for its students. Suggest three security measures they should put in place and explain why each one helps.[3]
✅ Mark scheme
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Any three: use WPA2/WPA3 encryption — encrypts all data transmitted over the network, making it unreadable if intercepted [1]; set a strong, unique network password — prevents unauthorised devices from connecting [1]; implement MAC address filtering — only pre-approved devices can connect to the school network [1]; use a separate guest network for visitors — isolates school systems from public access [1]; keep router firmware updated — patches known security vulnerabilities [1].
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Mini Test — 3.5e Wireless Networking

Timed exam conditions.

  • 8 questions · 10 minutes
  • 5 MCQ + 3 short answer
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