Endpoints and Media Types · Topic 2 of 5
Wi-Fi, Cellular and Wired Network Technologies
Compare wired copper and fiber with Wi-Fi on 2.4, 5 and 6 GHz and licensed cellular networks, and learn the common sources of interference for each.
- 4 min
- Copper is cheap but open to EMI and crosstalk. Fiber is not affected by EMI.
- Wi-Fi uses unlicensed bands. Cellular uses licensed bands.
- 802.11 Wi-Fi works in 2.4, 5 and 6 GHz.
What it is
Devices connect by wire, by Wi-Fi or by cellular, and each way has its own strengths.
Wired links use copper or fiber cable. Wi-Fi uses radio waves in unlicensed frequency bands, which anyone may use without a licence. Cellular uses radio too, but in licensed bands that a mobile carrier pays for and controls.
This page compares them and looks at what can disturb each one.
How it works
Cable is steady and fast, while radio is flexible and more easily disturbed.
Copper
Copper twisted pair carries electrical signals. It is cheap and easy to fit, but it is open to electromagnetic interference (EMI) from nearby electrical equipment.
Common sources are power cables, motors, fluorescent lights and lifts. Running data cable parallel to power cable can add noise. Cable that is badly terminated or damaged can also cause errors.
Neighbouring pairs can disturb each other, which is called crosstalk. The twisting of the pairs helps to reduce it.
Fiber
Fiber carries light, so it is not affected by EMI. It has high speed, long reach and very little signal loss.
The costs are higher, and fiber needs care when handled. It does not carry power, so a device at the far end needs its own power supply.
Wi-Fi and the 802.11 standards
Wi-Fi is based on the IEEE 802.11 family of standards. It works in three unlicensed bands.
| Band | Range | Speed | Crowding |
|---|---|---|---|
| 2.4 GHz | Longest, passes through walls best | Lowest | Most crowded, with few separate channels |
| 5 GHz | Medium | Higher | Less crowded, with more channels |
| 6 GHz | Shortest | Highest | Least crowded, newest, needs newer devices |
Newer standards generally add speed and efficiency. The 6 GHz band is used by Wi-Fi 6E and later devices, so an older device cannot join a 6 GHz network. Many access points offer more than one band at the same time.
Cellular
Cellular networks cover wide areas using towers. A mobile device uses a SIM or eSIM to identify itself to the carrier. The generations you will hear of are 4G, often called LTE, and 5G.
Because the carrier owns the licence for its bands, nobody else can transmit on them. This keeps cellular service more predictable than Wi-Fi, though signal can still weaken inside buildings or far from a tower.
Sources of wireless interference
Radio signals can be weakened or blocked by many things.
- Other Wi-Fi networks on the same channel, such as neighbours.
- Microwave ovens, which affect the 2.4 GHz band.
- Bluetooth devices and cordless phones, also in 2.4 GHz.
- Thick walls, metal, mirrors and water, which absorb or reflect signals.
- Distance from the access point or tower.
Moving to the 5 GHz band or changing channel often helps. Placing the access point in a central, open position helps too.
What to remember for the exam
Seven facts cover most questions on this topic.
- Copper is cheap but open to EMI and crosstalk. Fiber is not affected by EMI.
- Wi-Fi uses unlicensed bands. Cellular uses licensed bands.
- 802.11 Wi-Fi works in 2.4, 5 and 6 GHz.
- 2.4 GHz has the longest range and the most interference. 5 and 6 GHz are faster and have shorter range.
- Microwave ovens, Bluetooth and cordless phones can disturb 2.4 GHz.
- Cellular uses a SIM or eSIM and a carrier network, with 4G and 5G generations.
- Walls, metal and distance reduce wireless signal strength.
For a weak or noisy 2.4 GHz network, a good first fix is to move devices to 5 GHz or a different channel.
Common mistakes
These four errors appear again and again.
Thinking higher frequency means longer range. The higher bands carry more data, but they reach less far.
Calling cellular unlicensed. The carrier holds a licence for its bands. Wi-Fi is the unlicensed one.
Blaming the router for every slow Wi-Fi problem. Interference, distance and obstacles often cause the trouble.
Running copper beside power cables. Electrical noise can corrupt data on the copper.
A device that supports only 2.4 GHz cannot connect to a network that offers only 5 GHz or 6 GHz.
Check yourself
Work through these three questions.
Which wireless band has the longest range but the most crowding?
The 2.4 GHz band has the longest range and the most crowding.
What is the difference between licensed and unlicensed bands?
Unlicensed bands, used by Wi-Fi, can be used by anyone. Licensed bands, used by cellular, belong to the carrier.
Why is fiber a good choice near heavy electrical machinery?
Fiber carries light, so it is not affected by electromagnetic interference.
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