In this lecture, I will explore the channels available in the frequencies commonly used for wireless communications: 2.4 GHz, 5 GHz, and the emerging 6 GHz bands. Understanding these frequencies is crucial for effective network design, as each band has its own set of characteristics, advantages, and limitations. I will discuss the number of channels, their specific properties, and important considerations when deploying wireless networks. Let’s dive right into the explanation.

1. Channels in the 2.4 GHz Frequency

The 2.4 GHz frequency band consists of 14 channels in total. However, the availability of these channels depends on the regulations of different countries. For instance, the United States allows the use of channels up to 11, while other countries might permit access to channels 13 or even 14.

The channels in the 2.4 GHz band are numbered from 1 to 14, with each channel occupying a specific center frequency. For example, Channel 1 occupies a center frequency of 2412 MHz, while Channel 11 is centered at 2462 MHz. It’s important to note that different channels can cause interference with one another if not configured correctly.

Diagram 1: 2.4 GHz Channels Overview

In older technologies such as 802.11b and 802.11, the channel width is typically 22 MHz. This bandwidth is essential for understanding how channels overlap. When deploying multiple access points (APs) within the same wireless network, it is crucial to select non-overlapping channels to minimize interference.

1.1. Non-Overlapping Channels

In the 2.4 GHz band, there are only three non-overlapping channels: 1, 6, and 11. This means that if I deploy three access points in close proximity, I can place one AP on Channel 1, one on Channel 6, and one on Channel 11 without risking interference between them.

1.2. Practical Implications

Given the limited number of non-overlapping channels available in the 2.4 GHz band, it is often recommended to use the 5 GHz band whenever possible. The 2.4 GHz band is also crowded with devices like microwaves, Bluetooth devices, and other wireless networks, which can contribute to interference.

I personally experience interference in my environment, as many of my neighbors are also using the 2.4 GHz band. This highlights the importance of selecting the right frequency and channels when designing a wireless network to ensure optimal performance.

2. Channels in the 5 GHz Frequency

The 5 GHz band offers significantly more channels compared to the 2.4 GHz band. With a wider range of channels available, it is possible to achieve higher data rates and reduced interference. The channels in this frequency band typically have a 20 MHz channel width.

The channels in the 5 GHz band are organized into different UNII (Unlicensed National Information Infrastructure) bands, which include UNII 1, UNII 2, UNII 2 Extended, and UNII 3.

Diagram 2: 5 GHz Channels Overview

2.1. Channel Widths and Non-Overlapping Channels

In the 5 GHz band, the channels do not overlap, which provides a significant advantage over the 2.4 GHz band. The increased number of channels allows for better network performance and less interference from neighboring wireless networks.

Additionally, the 20 MHz channel widths can be combined to create wider channels, such as 40 MHz, 80 MHz, and even 160 MHz. Combining channels in this manner allows for greater throughput but can reduce the number of channels available for use.

2.2. DFS (Dynamic Frequency Selection)

An essential consideration when using the 5 GHz band is DFS (Dynamic Frequency Selection). Certain channels in the 5 GHz band are shared with radar systems, such as those used at airports or military facilities.

If an access point detects radar activity on a DFS channel, it is required to switch to another channel to avoid interference. Many modern access points, including those from MikroTik, can automatically detect radar signals and adjust their operation accordingly.

This capability is essential for ensuring that the wireless network remains operational even in areas where radar is present. The access point may take some time—often about a minute—to check for radar before it begins transmitting on the chosen channel.

2.3. Channel Widths and Throughput

When using the 5 GHz band, I can take advantage of wider channel widths to improve throughput. For example, if I use two 20 MHz channels together, I can create a single 40 MHz channel, which effectively doubles the data throughput.

Similarly, by combining two 40 MHz channels, I can create an 80 MHz channel, further increasing the available bandwidth. However, I must also be mindful of the coverage area when utilizing wider channels, as they typically have a shorter range compared to narrower channels.

3. Channels in the 6 GHz Frequency

The introduction of the 6 GHz band with 802.11ax (Wi-Fi 6E) represents a significant advancement in wireless technology. The 6 GHz band provides numerous additional channels, allowing for even greater capacity and reduced congestion in wireless networks.

Diagram 3: 6 GHz Channels Overview

3.1. Channel Widths in 6 GHz

The channels in the 6 GHz band are available in 20 MHz, 40 MHz, 80 MHz, and 160 MHz widths. The wide range of channels offers flexibility for network design, making it easier to accommodate a high number of devices without interference.

As more devices are connected to wireless networks, the availability of additional channels helps to maintain performance and user experience.

Conclusion

Understanding the channels available in the 2.4 GHz, 5 GHz, and 6 GHz frequency bands is crucial for designing effective wireless networks. The limited number of non-overlapping channels in the 2.4 GHz band necessitates careful planning to avoid interference and degradation of service.

The 5 GHz band provides more options and better performance, while the 6 GHz band offers a significant advancement in wireless technology, allowing for many additional channels for modern devices.

When deploying access points, I must consider the channel selections to ensure optimal performance and minimize interference. This awareness will lead to a more reliable and efficient wireless network.

Thank you for attending this lecture, and I look forward to seeing you in the next session!