An Introduction to 6-GHz Wi-Fi
Imagine you’re connecting to Wi-Fi with your phone, the network name of your Wi-Fi devices pops up along with all of your neighbors’. Besides seeing some of the ridiculous names your neighbors choose for their home networks (anyone see that “FBI Surveillance Van” Wi-Fi around?), there’s something else going on.
If you’re close enough to connect to their Wi-Fi, that means your signals are likely interfering with each other. It’s no wonder then why your Wi-Fi devices don’t meet their advertised speeds and latency.
One thing to understand is that many of these devices probably occupy the same frequency band. Such bands are considered valuable resources exclusive to some extent due to the fact that any channel of a band has to be put to one particular use like Wi-Fi transmission or satellite service. Of course, this is unless the industry implements successful shared use mechanisms.
Regulators like the Federal Communications Commission (FCC) manage the limited spectrum bands with much care and consideration. As a result, most of the Wi-Fi traffic today is crowded into two frequency bands (2.4 GHz and 5 GHz).
This issue, however, won’t last long. The FCC has recently proposed rules to open up the 6 GHz band for unlicensed use. So what does this mean for the Wi-Fi Alliance, manufacturers, and customers? Hopefully, Wi-Fi devices able to operate on this brand new band are coming to your home sooner rather than later.
A Quick Glance at the Current Standards and Bands
Wi-Fi devices follow certain standards. A standard typically requires devices to operate on one or multiple frequency bands. As shown in Figure 1, Wi-Fi Standards have evolved over the years, from 802.11b (Wi-Fi 1) to 802.11ax (Wi-Fi 6). To better understand the newest band, let’s first look at the current ones, i.e. the 2.4 GHz band and 5 GHz band.
Figure 1: Current Standards and Required Bands
2.4 GHz Band
As shown in Figure 2, 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. Note that permitted channels can be different among regions (e.g., Channel 14 is not permitted in the United States).
There is considerable overlap between adjacent channels. Overlapping channels configured at one location can cause interference. For example, if you deploy two access points near each other—one operating on Channel 1 and the other on Channel 2—wireless transmissions can experience severe slowdowns between each of the access points and their client devices. To avoid this issue, a certain combination of channels is typically used simultaneously at one location, free of interference. A possible combination, for instance, can be Channel 1, Channel 6 and channel 11 as shown below.
Figure 2: 2.4 GHz Band
5 GHz Band
The 5 GHz band has multiple 20 MHz channels, which can be combined into 40 MHz, 80 MHz, or even 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 3. Compared to its 2.4 GHz and 5 GHz counterparts, the 6 GHz band has the widest frequency range of 1,200 MHz.
According to Table 1, the 6 GHz band 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 3: 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 until recently to open band to Wi-Fi? One reason is that the recent boom of Wi-Fi devices has finally made the introduction of 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 defined as a reliable point-to-point microwave link that supports critical services. Common examples of fixed services include backhaul for police, fire vehicle dispatch, coordination of railroad train movements, and so on.
A mobile service, on the other hand, describes scenarios when a mobile transmitter communicates with a center; for example, television pickup stations transmit programming material from an event locale back to a studio.
As shown in Figure 3 and Table 2, the band is further divided into 4 sub-bands based on different conditions and requirements. The industry is most likely to figure out a shared-use mechanism for each of the sub-bands soon, or at least before the final regulations of 6 GHz band comes out.
The mechanisms include a system called AFC (Automated Frequency Coordination), which will be 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.
Since mobile services are typically licensed to operate over a wide area to allow maximum flexibility for coordination, it’s impractical to apply AFC to those sub-bands where mobile services prevail, as shown in Table 2. Hence the requirement for LPI use.
Table 2: 6-GHz Sub-Bands Conditions and Requirements
How Will the 6 GHz Band Benefit Wi-Fi?
Higher Speeds within a Shorter Range
As the name suggests, 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 of higher frequencies decrease faster along their propagation paths, especially through obstacles.
As a result, 6 GHz Wi-Fi 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. Generally speaking, the wider a band is, the more precise its positioning. Therefore, 6 GHz Wi-Fi will benefit applications featuring indoor positioning such as sweeping robots.
Less Interference by Legacy Devices
The most exciting part about 6 GHz Wi-Fi is its dedication to the latest standard 802.11ax (Wi-Fi 6). As shown in Figure 1, legacy devices based on any standard before Wi-Fi 6 are excluded from this new band. That means if your device operates on the 6 GHz band, it’s completely free from contention with every other legacy device. Also, 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.