Know and understand connecting a device to a network using wi-fi

4. Networks and the Effects of Using Them

Objective

Know and understand how to connect a device to a network using Wi‑Fi, and be able to analyse the advantages, limitations, security implications and emerging issues of wireless networking.

4.1 What Is a Network?

• A network is a collection of two or more devices (computers, tablets, phones, printers, etc.) linked together so they can share resources, data and services.
• Key network components (typical home or school layout):

  • Modem – converts the ISP’s signal (cable, DSL, fibre) to a form usable by the router.
  • Router – forwards traffic between the local network and the Internet; usually includes a built‑in firewall.
  • Access point (AP) – provides the wireless radio interface for Wi‑Fi devices; often integrated into a router.
  • Switch – connects multiple wired devices within the same LAN and forwards frames based on MAC addresses.
  • Hub – repeats incoming signals to all ports (simple but inefficient; largely obsolete).
  • Bridge – links two LAN segments and filters traffic to reduce collisions.
  • Network Interface Card (NIC) – hardware (wired or wireless) that enables a device to communicate on a network.
  • Firewall (hardware or software) – monitors and controls incoming/outgoing traffic according to security rules.

4.2 Types of Networks (Section 4.1 of the syllabus)

4.3 Wi‑Fi Basics

• Wi‑Fi (Wireless Fidelity) uses radio frequencies to transmit data between a device’s wireless NIC and an access point.
• Common frequency bands:

  • 2.4 GHz – longer range, more interference from other devices.
  • 5 GHz – higher speed, shorter range, less interference.
  • 6 GHz – introduced with Wi‑Fi 6E, even higher capacity.

• Wi‑Fi standards (IEEE 802.11):

  Standard	Maximum Data Rate	Typical Frequency	Minimum Security
  802.11b	11 Mbps	2.4 GHz	WPA/WPA2
  802.11g	54 Mbps	2.4 GHz	WPA/WPA2
  802.11n	600 Mbps (theoretical)	2.4 GHz / 5 GHz (dual‑band)	WPA2‑PSK
  802.11ac	1.3 Gbps (theoretical)	5 GHz	WPA2‑PSK / WPA3‑SAE
  802.11ax (Wi‑Fi 6/6E)	9.6 Gbps (theoretical)	2.4 GHz / 5 GHz / 6 GHz	WPA3‑SAE

• Typical indoor range: 30 m (2.4 GHz) to 15 m (5 GHz); outdoor line‑of‑sight can reach 100 m or more.

4.4 Short‑Range Wireless – Bluetooth

• Operates at 2.4 GHz but uses the IEEE 802.15.1 protocol.
• Range: up to 10 m (Class 2) or 100 m (Class 1).
• Common uses: wireless headphones, keyboards, file transfer between phones.
• Security: pairing codes, device whitelisting, optional AES‑CCM encryption.

4.5 Cloud Computing & Wi‑Fi

• Wi‑Fi provides the “last‑mile” connection for devices accessing cloud services such as Google Drive, Microsoft 365, online gaming platforms, and collaborative tools.
• Implications for students and staff:

  • Higher bandwidth requirements – a fast Wi‑Fi standard (802.11ac/ax) reduces latency for real‑time collaboration.
  • Data in transit is protected by two layers:

    1. Wi‑Fi encryption (WPA3 or WPA2).
    2. Transport‑layer security (HTTPS/TLS) used by cloud providers.

  • Monitoring data usage may be necessary where broadband caps apply.

4.6 Hardware Required for a Wi‑Fi Connection

1. Modem – connects to the ISP.
2. Wireless router or dedicated access point – creates the Wi‑Fi network and usually includes a built‑in firewall.
3. Device with a Wi‑Fi adapter – built‑in in most laptops, tablets, phones; external USB adapters for older PCs.
4. Optional accessories – Wi‑Fi extenders/repeaters, powerline adapters, mesh‑system nodes, or a switch for additional wired devices.

4.7 Steps to Connect a Device to a Wi‑Fi Network (AO2 – Application)

1. Power on the modem and router; confirm the Wi‑Fi (SSID broadcast) LED is active.
2. On the device, open Settings → Wi‑Fi (or Wireless Networks).
3. Locate the network’s SSID (the network name) in the list of available networks.
4. Select the SSID and click Connect.
5. Enter the security key (WPA2 or WPA3 password) when prompted.
6. The device requests an IP address from the router’s DHCP server; once received, a “Connected” status appears.
7. Test the connection:

   • Open a web browser and load a known website (e.g., www.google.com).
   • Run a speed‑test (e.g., speedtest.net) to verify throughput.

4.8 Network Security & Communication (AO3 – Analysis)

• Password policy – Minimum 12 characters, mix of upper‑/lower‑case letters, numbers and symbols; avoid common words.
• Encryption – Use WPA3‑SAE wherever possible; fall back to WPA2‑PSK if required. Never use WEP or an open network for sensitive work.
• Anti‑malware – Keep device antivirus/anti‑malware software up to date; enable real‑time scanning of downloads and email attachments.
• Virtual Private Network (VPN) – Provides an additional encrypted tunnel when accessing the intranet or extranet from public Wi‑Fi.
• E‑conferencing security – Use password‑protected meetings, enable waiting rooms, and ensure the platform uses TLS encryption.
• Intranet, Extranet and Internet:

  • Intranet – private internal network; access is restricted to staff and students.
  • Extranet – controlled access for external partners (e.g., suppliers, remote learners).
  • Internet – public global network; data is encrypted only if the service uses HTTPS/TLS.

4.9 Security Considerations (AO3)

• SSID management – Change the default SSID to a non‑identifiable name; hiding the SSID is optional and can hinder legitimate users.
• Router hardening:

  • Change the default admin username/password.
  • Enable the built‑in firewall.
  • Keep firmware up to date.
  • Consider MAC‑address filtering or a separate guest network for visitors.

• Physical security – Place the router out of easy reach, away from sources of interference (microwaves, cordless phones).

4.10 Advantages and Disadvantages of Wi‑Fi (AO3)

4.11 Common Troubleshooting Steps (AO2)

1. Confirm the router’s power and that the Wi‑Fi LED is illuminated.
2. Verify the device’s Wi‑Fi adapter is enabled (air‑plane mode off).
3. Check that the correct SSID and password are entered – watch for case‑sensitivity.
4. Restart the router and the client device.
5. Move the device closer to the router to eliminate range‑related issues.
6. Identify possible interference (microwaves, cordless phones, neighbouring Wi‑Fi on the same channel). Use a Wi‑Fi analyser app to select a less‑crowded channel.
7. Update the device’s network driver, router firmware, and, if applicable, mesh‑system firmware.
8. IP‑address checks: run ipconfig /all (Windows) or ifconfig/ip addr (Linux/macOS) to confirm a valid address and subnet mask.
9. DNS verification: ping a known domain (e.g., ping www.google.com). If the IP resolves but the site does not load, flush the DNS cache or change the DNS server (e.g., to 1.1.1.1).
10. Use ping or traceroute to test connectivity to the router (e.g., ping 192.168.1.1) and to an external host.
11. For persistent IP‑address problems, release/renew the DHCP lease or assign a static IP within the router’s subnet.

4.12 Emerging Technologies and Their Impact on Wi‑Fi (AO1)

• Internet of Things (IoT) – Thousands of low‑power sensors and actuators (smart lights, thermostats, wearables) rely on Wi‑Fi 6/6E for higher device density and lower latency.
• Artificial Intelligence (AI) – AI‑driven network management (dynamic channel selection, load balancing) improves Wi‑Fi performance in busy environments.
• Extended Reality (XR) – AR/VR – Requires very high bandwidth and low latency; Wi‑Fi 6E’s 6 GHz band helps meet these demands.
• These technologies increase the number of concurrent connections and the amount of data transmitted, making robust security and proper network design even more critical.

4.13 Example Calculation – Maximum Theoretical Data Rate (AO1)

Using the Shannon‑Hartley theorem, the maximum achievable data rate C (bits per second) is:

C = B × log₂(1 + SNR)

• B = channel bandwidth (Hz). For a 20 MHz Wi‑Fi channel, B = 20 × 10⁶ Hz.
• SNR = signal‑to‑noise ratio (linear, not dB). An SNR of 30 dB corresponds to a linear value of 10^(30/10) = 1 000.

Plugging the numbers in:

C = 20 × 10⁶ × log₂(1 + 1 000) ≈ 20 × 10⁶ × 9.97 ≈ 199 Mbps

This shows why a strong, clear signal (high SNR) is essential for achieving the advertised speeds of modern Wi‑Fi standards.

4.14 Summary

Connecting a device to a Wi‑Fi network involves understanding the hardware (modem, router/AP, NIC, firewall), the relevant standards (802.11 families), and the step‑by‑step configuration process. Students must also be able to analyse security measures, recognise the role of Wi‑Fi in cloud computing, troubleshoot common issues (including IP and DNS problems), and evaluate the impact of emerging technologies such as IoT, AI and XR on wireless networking.