An Introduction to 6 GHz Band for Wi-Fi 6E
Imagine you’re connecting to Wi-Fi with your mobile device. The name of your Wi-Fi networks appears alongside those of your neighbors. Apart from seeing the stupid names for other Wi-Fi networks, like “FBI Surveillance Van,” there’s something else going on.
If you’re close enough to connect to their Wi-Fi, that means the signals are probably interfering with each other. It’s why your Wi-Fi router doesn’t meet its advertised speed and latency.
Bands are considered valuable resources, and not all bands are open for us. Many devices probably occupy the same frequency band. Regulators like the Federal Communications Commission (FCC) manage the limited spectrum bands with much care and consideration. Most of the Wi-Fi traffic today is crowded into two frequency bands (2.4 GHz and 5 GHz).
This issue won’t last long. The FCC has proposed rules to open up the 6 GHz band for unlicensed use. What does this mean for the Wi-Fi Alliance, manufacturers, and customers? Wi-Fi devices operate on this brand new band and will come to your home sooner rather than later.
A Quick Glance at the Current Standards and Bands
Wi-Fi devices follow specific standards. A standard typically requires devices to operate on one or multiple frequency bands. Wi-Fi Standards have evolved over the years. To better understand the newest band, let’s first look at the current ones—the 2.4 GHz band and 5 GHz band.
2.4 GHz Band
As shown in Figure 1, the 2.4 GHz band has a channel range of 22 MHz. Adjacent channels can be combined into a 40 MHz channel, like “Channel 1 + 5” with a middle frequency of 2.422 GHz. There are different permitted channels in different countries and regions.
There is considerable overlap between adjacent channels. Overlapping channels configured at one location can cause interference. Suppose you deploy two access points near each other. In that case, one operating on Channel 1 and the other on Channel 2 can experience severe slowdowns between each access point and their client devices. A particular combination of channels is typically used simultaneously at one location to remove interference. A possible combination could be Channel 1, Channel 6, and channel 11, as shown below.
Figure 1: 2.4 GHz Band
5 GHz Band
The 5 GHz band has multiple 20 MHz channels, combined into 40 MHz, 80 MHz, or 160 MHz channels. It’s worth noting that permitted channels can be different among regions.
What Is the 6 GHz Band?
The 6 GHz band refers to the frequency band between 5.925 GHz and 7.125 GHz, as shown in Figure 2. Compared to its 2.4 GHz and 5 GHz counterparts, the 6 GHz band has the widest frequency range of 1,200 MHz. It also has the most channels among the three bands. The 6 GHz band also boasts the property of noninterference and good continuity, thus providing sufficient operational flexibility.
Figure 2: 6 GHz Band
Table 1: Theoretical Number of Available Channels on Each Band
Since the 6 GHz band features many benefits, why did it take regulators so long to open the band to Wi-Fi? One reason is that the recent boom of Wi-Fi devices has finally made the new band not only necessary but also urgent.
Operational Requirements of the 6 GHz Band
Another possible reason is that the industry has to deal with myriad incumbent applications already on the 6 GHz band. Before the 6 GHz band is opened up for Wi-Fi, the entire industry would have to invent mechanisms for sharing the band and preventing potential interference.
Incumbent applications can be classified into fixed services and mobile services. A fixed service is a reliable point-to-point microwave link that supports critical services. Common examples of fixed services include backhaul for police, fire vehicle dispatch, and coordination of railroad train movements.
On the other hand, a mobile service describes scenarios when a mobile transmitter communicates with a center. Television pickup stations transmit programming material from an event locale back to a studio.
Figure 3 and Table 2 show that the band is divided into four sub-bands based on different conditions and requirements. The industry is required to figure out a shared-use mechanism for each of the sub-bands.
The mechanisms include AFC (Automated Frequency Coordination), applied to the sub-bands U-NII-5 and U-NII-7. For all the Wi-Fi devices on sub-bands U-NII-6 and U-NII-8, they will be restricted to LPI (Lower Power Indoor) use only.
Mobile services are typically licensed to operate over a wide area to allow maximum flexibility for coordination. It’s therefore impractical to apply AFC to those sub-bands where mobile services prevail, as shown in Table 2.
Table 2: 6-GHz Sub-Bands Conditions and Requirements
How Will the 6 GHz Band Benefit Wi-Fi?
Higher Speeds within a Shorter Range
The 6 GHz band offers an inherently higher operating frequency than the previous bands, indicating a higher data rate and transmission speed. However, 6 GHz Wi-Fi may have a shorter range. Physics dictates, after all, that wireless signals at higher frequencies decrease faster along their propagation paths, primarily through obstacles.
As a result, Wi-Fi 6E that makes use of the 6 GHz suits the recent short-range, high-throughput, and low-latency applications being released today, like VR/AR, video streaming, and IoT.
More Precise Positioning
The 6 GHz band is the widest band ever opened for Wi-Fi devices. It is generally thought that wider bands provide for more precise positioning. Wi-Fi 6E will benefit applications featuring indoor positioning, such as sweeping robots.
Less Interference by Legacy Devices
The most exciting part about Wi-Fi 6E is its dedication to the latest standard 802.11ax (Wi-Fi 6). Legacy devices based on any standard before Wi-Fi 6E are excluded from this new band. If your device operates on the 6 GHz band, it’s completely free from contention with every other legacy device. New features like OFDMA become far more effective without legacy devices, thus fully realizing the potential of Wi-Fi 6. The performance boost in total will be game-changing.
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