Wired and Wireless Networks

Networks connect devices together so they can share data and resources. Every connection is either wired (a physical cable carries the data) or wireless (electromagnetic waves carry the data through the air).

Neither is universally better — the right choice depends on the situation. Understanding the trade-offs between them is essential for GCSE Computer Science.

Property	Wired	Wireless
Speed	Generally faster, especially over distance	Slower; degrades with distance and interference
Reliability	High — signal is contained in the cable	Lower — subject to interference from other devices
Security	More secure — physically harder to intercept	Less secure — signals can be intercepted remotely
Mobility	None — device must stay connected to cable	High — devices can move freely within range
Installation	Requires running cables; disruptive	Quick to set up; no cable routing needed
Cost	Higher upfront (cable, installation)	Lower installation cost; hardware can be more expensive

Most real networks use both: wired connections for servers, routers, and fixed workstations; wireless connections for laptops, phones, and other mobile devices.

Copper cables carry electrical signals along a metal conductor. They are the most widely used wired medium in local area networks.

The most common type in GCSE is twisted pair copper cable — two insulated copper wires twisted together to reduce interference. These are used in Ethernet connections inside buildings.

Advantages of copper cable:

• Inexpensive and widely available
• Easy to install and terminate
• Sufficient speed for most LAN applications

Disadvantages of copper cable:

• Maximum useful length is limited (typically around 100 m for standard Ethernet) — signal degrades over distance (attenuation)
• Susceptible to electromagnetic interference from nearby devices and cables
• Slower maximum data rates than fibre optic at long distances

Copper cable property	Typical value
Maximum cable length (Ethernet)	~100 m
Typical LAN data rate	1 Gbps (Gigabit Ethernet)
Signal type	Electrical
Susceptible to interference?	Yes

Copper is the standard choice for short-distance wired connections within a building where cost matters more than raw speed.

Fibre optic cables carry data as pulses of light through a glass or plastic core, rather than as electrical signals through metal.

Light travels along the cable by total internal reflection — bouncing off the inner walls of the glass core at a low angle so it stays inside and travels to the far end.

Advantages of fibre optic:

• Much faster data transmission than copper — supports speeds of tens of gigabits per second
• Much longer distances without signal degradation — can transmit reliably over kilometres
• Not susceptible to electromagnetic interference
• More secure — cannot be tapped by inductive methods used on copper

Disadvantages of fibre optic:

• More expensive than copper cable to purchase and install
• Fragile — glass core can crack if bent sharply
• Specialist equipment and expertise required to join (splice) cables

Fibre vs copper	Copper	Fibre optic
Signal type	Electrical	Light
Max effective distance	~100 m	Several km
Speed	Up to 1 Gbps (typical LAN)	Tens of Gbps
Cost	Lower	Higher
Interference	Susceptible	Immune

Fibre optic is used for the backbone connections between buildings, between cities, and across undersea cables — anywhere long distance and high speed matter more than installation cost.

Wi-Fi is the dominant wireless networking technology for LANs. Devices connect to a wireless access point (WAP) — typically integrated into a router — which transmits and receives data as radio waves.

Wi-Fi uses two main frequency bands:

• 2.4 GHz — longer range, slower speeds, more crowded (many devices use this band)
• 5 GHz — shorter range, faster speeds, less interference

Advantages of Wi-Fi:

• Devices can move freely within the coverage area
• No cables required — quick to add devices to the network
• Supported natively by almost all modern laptops, phones, and tablets

Disadvantages of Wi-Fi:

• Slower than wired connections — speed decreases with distance and through walls
• Signal can be blocked or reflected by thick walls, metal structures, and interference from other wireless devices
• Less secure than a wired connection — data must be encrypted (e.g. WPA2) to prevent eavesdropping

The range of a typical Wi-Fi access point is roughly 30–50 m indoors. Walls, floors, and other obstacles reduce this significantly.

Bluetooth is a short-range wireless technology designed to connect devices over distances up to approximately 10 m (some versions extend to 100 m).

It is used for personal area networks (PANs) rather than full LANs — connecting a keyboard to a laptop, a phone to a car, or wireless headphones to a device.

Feature	Bluetooth	Wi-Fi
Range	~10 m (standard)	~30–50 m indoors
Typical use	Peripheral devices, PANs	Network access, internet
Power consumption	Very low	Higher
Data rate	Lower	Higher
Infrastructure needed	None — device-to-device	Access point required

Advantages: Low power consumption, no infrastructure needed, simple device pairing.

Disadvantages: Short range; lower data rates than Wi-Fi; interference from other Bluetooth and 2.4 GHz devices.

Network designers choose transmission media based on the specific requirements of the situation.

Scenario	Best choice	Reason
Connecting a server in a data centre rack	Copper or fibre	Speed, reliability — no need for mobility
Backbone link between two buildings 500 m apart	Fibre optic	Distance too great for copper; high speed needed
Connecting a student laptop to the school network	Wi-Fi	Mobility; no cable to the desk
Connecting wireless headphones to a phone	Bluetooth	Short range, low power — no infrastructure needed
Security-sensitive workstation (e.g. finance, admin)	Copper	Harder to intercept than wireless; wired is more secure

Worked example — A school is designing a network. The server room connects to the main switch via a 150 m cable run. The library has 30 laptops that are moved between rooms. Which medium is best for each?

• Server room to switch (150 m): fibre optic — distance exceeds copper's 100 m limit; speed and reliability are critical
• Library laptops: Wi-Fi — mobility is essential; running 30 individual cables to moveable laptops is impractical

1. Stating that wireless is always less secure without explaining why

The mark-scheme expects a reason: "wireless signals can be intercepted by nearby devices because the signal travels through the air". Simply writing "wireless is less secure" does not earn full marks.

2. Confusing Wi-Fi and Bluetooth

Both are wireless but serve different purposes. Wi-Fi provides network/internet access over a larger area; Bluetooth connects nearby peripheral devices without any central access point. The exam may ask you to identify which is appropriate for a given scenario.

3. Claiming fibre optic carries electrical signals

Fibre optic carries light signals (pulses of light), not electrical signals. Saying "fibre uses electricity" is factually wrong.

4. Forgetting the distance limitation of copper

The ~100 m limit of copper Ethernet is a commonly tested fact. If a cable run exceeds 100 m in an exam scenario, the correct answer will involve fibre optic, not copper.

5. Describing interference as a problem for wired networks

Electromagnetic interference affects copper cables but not fibre optic cables (light is not affected by electromagnetic fields). Wireless networks also suffer from interference. Stating that "wired networks suffer from interference" without specifying copper is imprecise and may lose marks.