2.3 Given a scenario, select and configure wireless devices and technologies
Channels
📘CompTIA Network+ (N10-009)
When we talk about channels in wireless networks, we are discussing how Wi-Fi devices communicate on the same frequency without interfering with each other. Think of a channel as a specific “lane” in the airwaves that Wi-Fi devices use to send and receive data.
1. What are Non-Overlapping Channels?
- Definition:
Non-overlapping channels are wireless channels that do not interfere with each other because their frequency ranges do not overlap. - Importance:
Using non-overlapping channels is crucial in IT environments with multiple Wi-Fi access points (APs) to reduce interference, increase performance, and improve reliability.
2. How Non-Overlapping Channels Work
Wi-Fi uses different frequency bands, primarily:
- 2.4 GHz Band – Older, slower, longer range.
- 5 GHz Band – Faster, shorter range, more channels.
- 6 GHz Band – Newer (Wi-Fi 6E), even faster, many channels.
2.4 GHz Band Example
- The 2.4 GHz band has 14 channels (numbered 1–14), but each channel overlaps with the adjacent channels.
- Only 3 channels are truly non-overlapping: 1, 6, and 11.
Why only 3?
- Each channel has a “width” (usually 20 MHz) that takes up part of the frequency spectrum.
- If you use channels next to each other, their frequency ranges overlap, causing interference and slower Wi-Fi.
✅ Best practice: In an office with multiple APs on 2.4 GHz, assign channels 1, 6, or 11 to avoid interference.
5 GHz Band Example
- The 5 GHz band has more channels, many of which are non-overlapping.
- Typical 20 MHz channels in 5 GHz: 36, 40, 44, 48, 149, 153, 157, 161.
- Many channels do not overlap, so you can place multiple APs close to each other without interference.
6 GHz Band Example (Wi-Fi 6E)
- Even more channels are available, almost all non-overlapping.
- This makes high-density networks much more efficient, like offices, campuses, or large buildings.
3. Why Non-Overlapping Channels Matter in IT Environments
In an IT environment:
- Multiple APs: If you have several APs in a building, using overlapping channels can slow down the network for everyone.
- High-density areas: Places like office floors, conference rooms, or labs need careful channel planning to avoid interference.
- Roaming: Non-overlapping channels help devices move from one AP to another smoothly without dropping connections.
Example in IT terms:
- AP1 on channel 1, AP2 on channel 6, AP3 on channel 11 → all 2.4 GHz APs work without interfering.
- If AP1 is on 2 and AP2 is on 3 → devices may get slower speeds and experience packet loss due to interference.
4. Exam Tips for Non-Overlapping Channels
- Remember 2.4 GHz: Only channels 1, 6, 11 are non-overlapping.
- 5 GHz has many non-overlapping channels, and 6 GHz even more.
- Goal: Assign channels so that neighboring APs do not use overlapping channels.
- Channel width: Using wider channels (40 MHz or 80 MHz) may reduce the number of non-overlapping channels, so plan accordingly.
5. Summary Table
| Frequency Band | Total Channels | Non-Overlapping Channels | Notes |
|---|---|---|---|
| 2.4 GHz | 14 | 1, 6, 11 | Limited channels, high interference risk |
| 5 GHz | 25+ | Many (depends on region) | Better performance, less interference |
| 6 GHz (Wi-Fi 6E) | 59+ | Almost all | Ideal for dense networks |
Key takeaway:
Non-overlapping channels are used to reduce interference between access points, ensuring better Wi-Fi performance. Always plan channel assignment in multi-AP environments to avoid overlap, especially in 2.4 GHz networks.
