Show understanding of the differences between and implications of the use of wireless and wired networks

Published by Patrick Mutisya · 14 days ago

Cambridge A-Level Computer Science 9618 – Networks (2.1)

2.1 Networks – The Internet

Objective

Show understanding of the differences between and implications of the use of wireless and wired networks.

Key Concepts

  • Physical media: copper cable, fibre optic cable, radio waves.
  • Transmission characteristics: bandwidth, latency, attenuation, interference.
  • Network topologies and standards (e.g., Ethernet, Wi‑Fi).
  • Security considerations for each type of network.
  • Cost, scalability and maintenance implications.

Comparison of Wired and Wireless Networks

AspectWired NetworksWireless Networks
Physical mediumTwisted‑pair copper (e.g., Cat5e/6), coaxial cable, fibre opticRadio frequency (RF) or infrared electromagnetic waves
Typical bandwidth10 Mbps – 100 Gbps (depending on cable type)Up to several Gbps (e.g., 802.11ax), but real‑world often lower due to contention
LatencyLow (typically < 1 ms for LAN)Higher (often 5–30 ms, can increase with distance and obstacles)
Signal attenuationPredictable; limited by cable length (e.g., 100 m for Ethernet)Strongly affected by distance, walls, interference from other RF devices
SecurityPhysical security – access requires physical connectionRequires encryption (WPA3, etc.) and authentication; vulnerable to eavesdropping and rogue APs
Installation & maintenanceHigher initial cost (cabling, conduit), but stable once installedLower installation cost, but requires regular firmware updates and site surveys
MobilityStationary – devices must be physically connectedHigh – devices can move within coverage area
ScalabilityLimited by port density and cabling logisticsScales easily by adding more access points, but spectrum limits apply

Implications for Network Design

  1. Performance requirements: For latency‑sensitive applications (e.g., online gaming, high‑frequency trading) wired links are preferred because of their lower latency and higher guaranteed bandwidth.

  2. Physical environment: In historic buildings or campuses where cabling is impractical, wireless provides a feasible solution, though designers must account for attenuation caused by walls and furniture.

  3. Security policy: Wired networks benefit from “security through physical isolation”. Wireless networks must implement strong encryption, regular key rotation, and intrusion detection to mitigate eavesdropping risks.

  4. Cost considerations: Initial deployment of wired infrastructure can be expensive, especially over large distances. Wireless reduces upfront costs but may incur ongoing expenses for spectrum licensing (in some cases) and maintenance.

  5. Scalability and future‑proofing: Fibre‑optic cabling offers virtually unlimited bandwidth growth, making it ideal for backbone links. Wireless technologies evolve rapidly (e.g., Wi‑Fi 6E, 5G), allowing incremental upgrades without physical rewiring.

Mathematical Modelling of Bandwidth and Latency

The total transmission time \$T\$ for a data packet of size \$S\$ bits over a link with bandwidth \$B\$ (bits per second) and propagation delay \$D\$ is approximated by:

\$T = \frac{S}{B} + D\$

For wired Ethernet (e.g., \$B = 1\,\text{Gbps}\$, \$D \approx 0.5\,\text{ms}\$) and a 1500‑byte Ethernet frame (\$S = 12\,000\$ bits), the transmission time is:

\$T_{\text{wired}} = \frac{12\,000}{10^9} + 0.5\times10^{-3} \approx 0.500012\ \text{ms}\$

For a typical Wi‑Fi link (\$B = 300\,\text{Mbps}\$, \$D \approx 10\,\text{ms}\$):

\$T_{\text{wireless}} = \frac{12\,000}{3\times10^8} + 10\times10^{-3} \approx 10.00004\ \text{ms}\$

This illustrates why wired connections are preferred for low‑latency requirements.

Suggested Diagram

Suggested diagram: A side‑by‑side illustration of a wired LAN (copper/fibre cables connecting switches, servers, and PCs) and a wireless LAN (access points providing radio coverage to laptops, smartphones, and IoT devices). Include labels for bandwidth, latency, and typical coverage radius.

Summary

Both wired and wireless networks have distinct advantages and limitations. Effective network design for the internet and organisational environments requires a balanced approach that considers performance, security, cost, and future scalability. Understanding the quantitative differences—such as bandwidth, latency, and attenuation—allows engineers to make informed decisions about when to deploy each technology.