2.2 Explain wireless networking technologies
📘CompTIA A+ Core 1 (220-1201)
Wireless Networking Channels
Wireless networking uses channels to send and receive data over the air. A channel is like a specific lane in the airwaves where devices communicate without interfering with each other. Channels are part of a frequency band (like 2.4 GHz or 5 GHz). Understanding channels is essential because correct channel use improves Wi-Fi performance, reduces interference, and ensures compliance with regulations.
1. Regulations
Wireless communication is regulated by government organizations to prevent interference with other services:
- FCC (USA) – Federal Communications Commission
- ETSI (Europe) – European Telecommunications Standards Institute
- Other countries have their own regulators.
Key points:
- Not all channels are allowed in every country.
- Some channels may require dynamic frequency selection (DFS) to avoid interfering with radar systems.
- Devices automatically select allowed channels based on local regulations.
Example in IT environments:
A Wi-Fi access point (AP) in an office in the USA will only use channels allowed by the FCC. If an AP tries to use a channel that’s illegal in that country, it won’t broadcast.
2. Channel Selection
Choosing the right channel is critical to reduce interference from:
- Other Wi-Fi networks
- Bluetooth devices
- Microwave ovens
- Wireless security cameras
Wi-Fi networks can either auto-select channels or allow an administrator to manually choose channels.
Best practices for IT environments:
- Use a Wi-Fi analyzer to see which channels are crowded.
- Avoid overlapping channels in dense office networks.
- Separate 2.4 GHz and 5 GHz networks to reduce congestion.
3. Channel Widths
Channel width determines how much data can flow at once:
| Width | Example Use | Notes |
|---|---|---|
| 20 MHz | Standard Wi-Fi | Less interference, more reliable in crowded areas |
| 40 MHz | High-speed connections | May interfere with nearby networks |
| 80 MHz | Very high-speed (5 GHz) | Good for streaming, fewer overlapping channels |
| 160 MHz | Ultra high-speed | Rarely used, very few available channels |
IT impact:
- Wider channels = higher data rates, but more interference risk.
- Narrow channels = slower but more stable in busy environments.
4. Frequencies
Wi-Fi operates on different frequencies, measured in gigahertz (GHz):
- 2.4 GHz – Older, longer range, slower speed, more interference
- 5 GHz – Faster, shorter range, more channels, less interference
- 6 GHz (Wi-Fi 6E) – Very fast, new band, limited devices and range
IT example:
- A warehouse uses 2.4 GHz APs for coverage across large distances.
- An office uses 5 GHz APs for fast speeds to laptops and VoIP phones.
- A data center uses 6 GHz Wi-Fi 6E for high-speed wireless backups.
5. Bands
Bands are the ranges of frequencies:
| Band | Channels | Pros | Cons |
|---|---|---|---|
| 2.4 GHz | Channels 1–11 (US), 1–13 (EU) | Long range, good penetration | Crowded, slow, overlapping channels |
| 5 GHz | Channels 36–165 | Fast, many non-overlapping channels | Shorter range, not all devices support it |
| 6 GHz | Channels 1–233 (varies) | Very fast, low interference | Very short range, new, limited support |
Important IT concept:
- Channels within a band can overlap (mainly 2.4 GHz), which causes interference.
- Some channels are non-overlapping, which is preferred in IT setups for stable performance.
Non-overlapping channels for 2.4 GHz (US): 1, 6, 11
- Using these prevents overlap and reduces interference.
Summary for Exam
- Regulations: Channels are controlled by government rules. APs must comply.
- Channel Selection: Pick the least congested channel to reduce interference.
- Channel Widths: Wider = faster, narrower = more stable.
- Frequencies: 2.4 GHz (long range), 5 GHz (fast), 6 GHz (ultra-fast, new).
- Bands: Each band has a range of channels. 2.4 GHz overlaps, 5 GHz has more non-overlapping channels, 6 GHz is newest and fastest.
Key IT tip: In offices or IT networks, always check which channels are crowded and use non-overlapping channels for better Wi-Fi performance.
