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AQA 7517 · Paper 2 · 4.9.2b

Wireless
Networks

WiFi · SSID · WPA2 · Bluetooth · 4G/5G · Section 4.9

WHAT YOU'LL LEARN
WiFi standards · SSID and WPA2 · Bluetooth · 4G/5G · Wireless security risks
AQA SPEC LINK
4.9.2 — Wireless networks: WiFi, SSID, encryption, Bluetooth, 4G/5G
WiFi

WiFi — Wireless LAN

WiFi uses radio waves (2.4 GHz or 5 GHz bands) to transmit data wirelessly between devices and a Wireless Access Point (WAP/router).
802.11n (WiFi 4) — up to 600 Mbps, 2.4/5 GHz
802.11ac (WiFi 5) — up to 3.5 Gbps, 5 GHz
802.11ax (WiFi 6) — up to 9.6 Gbps, 2.4/5/6 GHz, better for many devices
2.4 GHz: longer range, more interference; 5 GHz: shorter range, faster, less congested
SSID & WPA2

SSID and WPA2 Security

SSID — Service Set Identifier
The name of a WiFi network broadcast by the access point. Devices scan for SSIDs to discover available networks. SSID can be hidden but this provides minimal security.
WPA2 — Wi-Fi Protected Access 2
Current standard wireless security protocol. Uses AES encryption (128-bit or 256-bit) to encrypt traffic. WPA3 is newer but WPA2 is on the AQA spec. Requires a password (pre-shared key) to join.
Wireless Security Risks

WiFi Security Threats

Eavesdropping — radio signals can be intercepted; WPA2 encryption prevents reading the data
Evil twin attack — attacker sets up a fake WiFi network with same SSID as legitimate one; victims connect and all traffic passes through attacker
Password cracking — weak WPA2 passwords can be brute-forced offline after capturing the 4-way handshake
Use WPA2/WPA3, strong password, VPN on public WiFi
Bluetooth

Bluetooth

Bluetooth is a short-range wireless technology for connecting devices within ~10 metres. Operates on 2.4 GHz using frequency hopping to avoid interference.
Bluetooth 5.0+ — range up to 400m (line of sight); speed up to 2 Mbps
Used for: headphones, keyboards, mice, smartwatches, speakers, IoT sensors
Bluetooth Low Energy (BLE) — ultra-low power; used in fitness trackers, beacons
Pairing: devices exchange keys to authenticate before connecting
4G & 5G

Mobile Networks: 4G & 5G

4G LTE
Up to 150 Mbps typical. Covers most urban/suburban areas. Used for smartphone internet, streaming, calls over LTE.
5G
Up to 10 Gbps theoretical. Low latency (~1ms). Enables: autonomous vehicles, smart cities, AR/VR, industrial IoT. Uses high-frequency mmWave (short range) and sub-6 GHz (longer range) bands.
Wired vs Wireless

Wired vs Wireless Comparison

FeatureWired (Ethernet)Wireless (WiFi)
SpeedUp to 10 GbpsUp to 9.6 Gbps (WiFi 6)
SecurityMore secureSignals can be intercepted
MobilityRestricted by cableMove freely within range
InterferenceNoneWalls, other devices
Network Security

Securing a Wireless Network

Use WPA2/WPA3 — not WEP (easily cracked in minutes)
Strong passphrase — minimum 12 characters, mixed characters
Change default router credentials — default admin/admin is publicly known
MAC address filtering — whitelist specific device MACs (can be spoofed but adds a layer)
Hide SSID — stops casual discovery (but dedicated attackers can still find it)
Guest network — isolate IoT/visitor devices from main network
AQA Exam Style

Practice Question

AQA 7517 — Paper 2 Style
(a) Explain what an SSID is and how it is used when connecting to a WiFi network. [2]
(b) A coffee shop offers free unencrypted WiFi. Describe ONE security risk this poses to customers. [2]
(c) Give TWO differences between Bluetooth and WiFi. [2]
(d) State ONE advantage of 5G over 4G for self-driving vehicles. [1]
[7 marks]
2 marks
(a) SSID is the name/identifier of a WiFi network broadcast by the access point [1]; when connecting, a device selects the SSID and provides the correct password to authenticate [1]
2 marks
(b) Data sent over unencrypted WiFi can be intercepted (eavesdropping) [1]; attackers on the same network can read passwords, emails, and other sensitive data in plaintext [1]
2 marks
(c) Any 2: WiFi has longer range / WiFi has higher data rates / Bluetooth uses less power / Bluetooth is for device-to-device (PAN) vs WiFi for LAN internet access / Bluetooth uses frequency hopping
1 mark
(d) 5G has much lower latency (~1ms vs ~50ms for 4G) enabling real-time communication for vehicle-to-vehicle and vehicle-to-infrastructure safety decisions
Summary

Key Points to Remember

WiFi — IEEE 802.11; 2.4/5 GHz; WPA2/WPA3 encryption; SSID = network name
WPA2 — AES encryption; requires password; current standard (WPA3 is newer)
Bluetooth — short range (~10m), 2.4 GHz, low power, pairing required
4G — 150 Mbps, ~50ms latency; 5G — 10 Gbps, ~1ms latency, IoT/autonomous vehicles
Secure WiFi: WPA2/3, strong password, change defaults, MAC filtering
🎉 Lesson complete — move to the quiz!