Wi-Fi 6e: The Next Generation of Wireless
Explore the intricacies of the complex evolution of Wi-Fi technology.
Over the past 20 years, IEEE 802.11, commonly referred to as Wi-Fi, has evolved from a few megabits to multi-gigabit speeds — a 1000-fold increase in throughput. The standard has continuously advanced through protocol improvements including 802.11n, 802.11ac and 802.11ax.
The standards were given a new naming system in 2018, identifying Wi-Fi generations by a numerical sequence which correspond to major advancements in Wi-Fi, with Wi-Fi 6 representing the 802.11ax standard. Each generation of Wi-Fi standards provided improvements, including support higher order of modulation schemes such as 64 Quadrature Amplitude Modulations (QAM), 256 QAM, 1024 QAM and transmission of multiple streams to a single client or multiple clients simultaneously.
Additionally, efforts have been made to improve spectral efficiency which characterizes how well the system uses the available spectrum. Multi-user techniques such as multi-user, multiple-input, multiple-output (MU-MIMO) and orthogonal frequency-division multiple access (OFDMA) have been introduced to improve network efficiency and network capacity.
As newer Wi-Fi standards were released and implemented, the world began to change as markets opened and new technology emerged. Each standard is built on the previous standard with improvement in speed and reliability.
If you are looking to buy new wireless networking gear or a mobile device, you may be overwhelmed by the number of available options. Since Wi-Fi was first released in 1997, standards have been continually evolving which typically meant faster speeds and network/spectrum efficiency. As capabilities were added to the 802.11 standard, they became known by their amendment (802.11b, 802.11g, etc.). Tables 1 and 2 and Figure 3 below list different standards and max theoretical data rates achieved with those standards.
Typically practical throughput rates are lower than theoretical based on several factors including modulation rate, forward error correction coding, the signal degradation with distance, bandwidth, MIMO multiplier, guard interval and typical error rates. The 802.11 family consists of a series of half-duplex over the air modulation techniques that use the same basic protocol. In the following sections, we'll cover the basics of each Wi-Fi standard.
The evolution of Wi-Fi
Wi-Fi 1, or IEEE 802.11b products, started appearing on the market in mid-1999. It has a maximum theoretical data rate of 11 Mbps and uses the same carrier sense multiple access with collision avoidance (CSMA/CA) medium access method defined in the original standard. The wired-like throughput (at the time) of 802.11b, along with consumer-friendly pricing, led to wide acceptance of 802.11b as a wireless technology.
802.11b uses the ISM (industrial/scientific/medical) unlicensed frequency band from 2400-2500 MHz. 802.11b is a direct extension of direct sequence spread spectrum (DSSS) and uses complementary code keying (CCK) as its modulation technique. 802.11b is used in point-to-multipoint configuration, which allows an access point to communicate with mobile clients within the range of the access point.
The range depends on the radio frequency environment, sensitivity of the receiver and output power. 802.11b defines 3 channels that operate at 11 Mbps and has a bandwidth of 22 MHz but scales back to 5.5, then to 2, then to 1 Mbps (adaptive rate selection) in order to decrease the rate of re-broadcasts that results from errors.
This standard shares the same frequencies of other wireless standards, meaning that home wireless devices such as microwave ovens, Bluetooth® devices and cordless phones can cause interference with Wi-Fi.
The Wi-Fi 2 standard (IEEE 802.11a) uses the same protocol as the original standard. Wi-Fi 2 uses a 52-subcarrier OFDM with a maximum theoretical data rate of 54 Mbps and operates at 5 GHz. This achieves a practical throughput of mid 20 Mbps. Other data rates it supports include 6, 9, 12, 18, 24, 36 and 48 Mbps.
802.11a is not interoperable with 802.11b because they operate in different unlicensed ISM frequency bands. The 5 GHz spectrum gives 802.11a a significant advantage over 2.4 GHz because it has a high carrier frequency and the effective overall range is less than 802.11b/g. Also, some products were not widely accepted initially because of cost, low range and incompatibility with 802.11b.
OFDM has 52 subcarriers; 48 are for data and 4 are pilot subcarriers, with a carrier separation of 312.5 kHz. Each of these subcarriers can be binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), 16 QAM or 64 QAM.
The bandwidth of channel is 20 MHz with occupied bandwidth of 16.6 MHz. Symbol duration is 4 μsec, which includes a guard interval of 0.8 μsec. OFDM advantages include reduced multipath effects in reception and increased spectral efficiency.
Wi-Fi 3, or IEEE 802.11g, became available in the summer of 2003. It uses the same OFDM technology introduced with 802.11a. Like 802.11a, it supports a maximum theoretical rate of 54 Mbps. But like 802.11b, it operates in the crowded 2.4 GHz and is susceptible to interference issues.
802.11g is backwards compatible with 802.11b (i.e. 802.11b devices can connect to an 802.11g access point). 802.11g was able to handle dual-band or dual-mode access points using 802.11a and 802.11b/g.
With Wi-Fi 4, or IEEE 802.11n, Wi-Fi became even faster and more reliable. It provided for wide adoption of wireless as a reasonable alternative to wired connections.
Wi-Fi 4 added MIMO and 40 MHz channels to the physical layer and frame aggregation to the MAC layer. MIMO is a method for multiplying the capacity of a radio link using multiple transmit and receive antennas to exploit multipath propagation. These antennas need to be spatially separated so that the signal from each transmit antenna to each receive antenna has a different spatial signature, so that on the receiver it can separate these streams into parallel independent channels.
Channels operating with a width of 40 MHz doubles the channel width and provides twice the physical data rate over a single 20 MHz channel. The 802.11n standard allows up to 4 spatial streams with a maximum theoretical throughput of 600 Mbps.
The 802.11n standard raised the bar on Wi-Fi and provided a platform with many years of high throughput and reliability for large and small organizations. Widespread adoption allowed the user base to rely far more on Wi-Fi and led to the user expectation that Wi-Fi is the default way to connect devices to the network.
Wi-Fi 5 (IEEE 802.11ac) revved-up Wi-Fi by providing gigabit speeds per second, achieved by extending the 802.11n concepts including: wider bandwidth (up to 160 MHz), more MIMO spatial streams (up to 8), downlink multi-user MIMO (up to four clients) and high-density modulation (up to 256 QAM). 802.11ac supports 256 QAM at 3/4, 5/6 coding rate (MCS8/9), which requires 6 dB tougher system level EVM (-34 dB) requirements.
802.11ac works exclusively in the 5 GHz band, so dual-band access points and clients will continue to use 802.11n at 2.4 GHz. The first wave of 802.11ac was released in 2013 and supported only 80 MHz channels and up to 3 spatial streams, delivering up to 1300 Mbps at the physical layer.
Second wave products, or 802.11ac wave 2 products, were released in 2015, support more channel bonding, more spatial streams and MU-MIMO. MU-MIMO is a significant advancement of 802.11ac. While MIMO directs multiple streams to a single user, MU-MIMO can direct spatial streams to multiple clients simultaneously thus improving network efficiency.
Also, 802.11ac uses a technology called beamforming. With beamforming, the antenna basically transmits the radio signals, so they are directed at a specific device. 802.11ac access points are backwards compatible with 802.11b, 11g, 11a and 11n, which means all the legacy clients work fine with an 802.11ac (Wi-Fi 5) system.
Wi-Fi 6 or 802.11ax standard
Wi-Fi 6, or IEEE 802.11ax, is the sixth generation of Wi-Fi, built on the strengths of 802.11ac and provides more wireless reliability and capacity. 802.11ax achieves these benefits by using denser modulation (1024 QAM), OFDMA, reduced subcarrier spacing (78.125 kHz) and scheduled-based resource allocation.
More importantly, 802.11ax (unlike 802.11ac) is a dual-band 2.4 and 5 GHz technology. 802.11ax was designed to coexist efficiently with 802.11a/g/n/ac clients and provide maximum compatibility. The technology uses OFDMA (a technology borrowed from cellular systems), which allows resource units (RUs) that divide the bandwidth according to the needs of the clients and provide multiple individuals with the same user experience at faster speeds.
Within 802.11ac, Wi-Fi channels were broken down into a collection of smaller OFDM sub-channels, which meant that at any given point, carriers in each physical layer convergence protocol (PLCP) protocol data unit (PPDU) could be broken down into sub-channels. However, OFDMA (802.11ax) has individual groups of subcarriers which are individually allocated to clients as resource units on a per-PPDU basis.
What is Wi-Fi 6e?
Wi-Fi 6 and older generations of Wi-Fi utilize the 2.4 GHz (2400 to 2495 MHz) and 5 GHz (5170 to 5835 MHz) radio bands. One of the major challenges in the 5 GHz band is that while the Wi-Fi 5 and 6 standards support the idea of allocating 160MHz channels, with the frequency spectrum, it is not practical to do so and still maintain channel diversity.
Wi-Fi 6e operates in the newly allocated 6 GHz band from 5.925 to 7.125 GHz. The 6 GHz spectrum is similar to running Wi-Fi 6 over 5 GHz but provides additional non-overlapping channels. This means that Wi-Fi 6e allows for 14 additional 80 MHz channels and 7 additional 160 MHz channels. This now makes it practical to achieve the benefits of the wider channels while still maintaining channel diversity for adjacent access points.
Why does Wi-Fi 6e matter?
To everyday users and enterprises, Wi-Fi 6e will bring significant improvements over Wi-Fi 5 and even Wi-Fi 6. Wi-Fi 6e provides more bandwidth, better performance and a reduction of slower technology devices, all combining to offer speed and more compelling user experiences.
For example, institutions of learning will be able to deploy virtual reality (VR) learning at scale, with every student in a classroom simultaneously using a VR headset. Previous network limitations in throughput would have made this unachievable.
In healthcare, the increased data rates would allow patients to see an MRI on a retina display while your doctor annotates results right in front of you. These examples would not be possible were it not for the wide channels offered by Wi-Fi 6e.
In heavily populated environments such as stadiums, train stations, large public venues or office buildings, there would be a huge improvement in wireless capacity. In these type of large environments, channel diversity and reuse becomes a significant challenge that Wi-Fi 6e can help solve. Establishments will be able to deliver a better customer experience, and it will allow more users to have live video connections anywhere, from a subway platform to Times Square.
As workspaces evolve, Wi-Fi must evolve to keep pace with the changing landscape of devices needing to connect to company infrastructures. As we see in Figure 4, numerous factors will influence to need for more bandwidth. Factors like:
- Wireless as the primary network: In the past, companies usually had a combination of physical LAN connections and wireless, but many are finding it more cost effective to deploy all wireless office spaces.
- How people work is changing: Employees are preferring to move around with devices to better support collaboration efforts on projects.
- More devices needing to connect: The exponential growth of IoT and smart devices means more things connecting and more traffic.
The benefits of Wi-Fi 6 and 6e
Aside from higher speeds, there are also other benefits provided by the Wi-Fi 6 and 6e standards.
Better network efficiency
Not only does Wi-Fi 6e offer better performance, it is highly efficient thanks to its 6GHz frequency band, which significantly reduces congestion on a wireless network. Wi-Fi 6e compatibility will includeall previously released Wi-Fi bands, including 5GHz and 2.4GHz, which means you will be able to take full advantage of Wi-Fi networks without encountering interference, latency drops or network congestion.
This will enable network user to have faster gaming over the network, better streaming performance and much more. Wi-Fi 6e devices will be able to support denser deployments as well as take care of network-intensive tasks much more efficiently.
Newer Wi-Fi 6 and 6e compatible devices will use far less battery by efficiently using target wake time (TWT).
TWT helps connected devices customize when and how they receive data signals from Wi-Fi. It makes it much easier for devices to sleep while waiting for the next necessary Wi-Fi transmission. In turn, this has the potential to increase the battery life for devices.
The Wi-Fi Alliance has specified that Wi-Fi 6e will be able to utilize 14 additional 80 Mhz channels or 7 additional super-wide 160 Mhz channels in the 6 Mhz range. This in turn will improve end-user network speeds by reducing network latency and increasing overall performance.
Through additional physical capability, Wi-Fi 6e offers users a 4x better throughput even in dense and congested environments where multiple networks are operating simultaneously.
Will I need to upgrade hardware to use Wi-Fi 6e?
Wi-Fi 6e is designed to add additional spectrum for wireless networking. If you recall, 802.11a added 5Ghz spectrum for the first time, but was not compatible with 802.11b that used the 2.4Ghz spectrum. It took a bit of time for laptop and device manufacturers to embed the new Wi-Fi NICs, including the new spectrum band into devices. It was not possible to add support for the new 5GHz band with simply a software update.
Wi-Fi 6e will have to overcome similar challenges. You will need new hardware that supports the 6Ghz spectrum to leverage the improvements from Wi-Fi 6e. This includes the Wi-Fi 6e access points plus PCs, smartphones and other devices with Wi-Fi NICs capable of communicating on the 6 GHz band.
The first products that will support Wi-Fi 6e are expected to be launched in late 2020 and the spring of 2021. Once you have a fully Wi-Fi 6e compatible setup you should be able to see the benefits right away.
Wi-Fi 6e developments
The FCC recently approved the expansion of Wi-Fi into the 6 GHz band for unlicensed use later in 2020, which will clear the way for Wi-Fi 6e in the United States. This is the largest spectrum addition since the FCC cleared the way for the 5 GHz band, so it’s a big deal.
The new spectrum quadruples the amount of space available for Wi-Fi access points and other devices, which means a lot more bandwidth and a lot less interference for any device that can take advantage of it. Many other countries have yet to approve Wi-Fi 6e, so it still faces some challenges from a global perspective.
What will Wi-Fi 6e be used for?
Aside from the general benefits provided by the significant increase in Wi-Fi spectrum, we anticipate that organizations may take an approach of band-allocation by user community. For example, you might employ 2.4 GHz for Guest Wi-Fi, 5 GHz for general-purpose enterprise wireless devices (like sensors and conference room screen sharing) and the newer 6 GHz band for mission-critical applications like employee wireless voice/video collaboration.
The lower interference potential, as well as much larger quantity of radio spectrum, opens up new possibilities for providing high quality, reliable applications at the 6 GHz band which will further cement Wi-Fi as the primary network access.
We are also likely to see an increase in IoT devices which today use wired connections, such as IP video surveillance cameras and other sensors which require significant bandwidth. We would expect this to accelerate IoT device deployments in the wireless spectrum, which will be more flexible and less cost than wired connections.
As users connect more and more devices, current wireless airspace will become highly congested, creating resource contention and degrading performance. Migrating to Wi-Fi 6 and Wi-Fi 6e will be critical for infrastructure to meet ever increasing demands users and devices are placing on your wireless networks.
Although many companies are still working to rollout Wi-Fi 6 compatible access points, many of them already have Wi-Fi 6 devices available. We are lucky to have early versions Wi-Fi 6 products from top vendors operating in our Advanced Technology Center (ATC), where we have been helping validate systems architectures and understanding best practices for deploying these technologies at scale. The time to learn and get familiar with Wi-Fi 6 solutions is now, so visit our ATC or schedule a workshop and let WWT help your organization on the journey to modernize.
We are closely following the release of products for Wi-Fi 6e — both access points and user devices — and as soon as these are available from manufacturers we will be adding these into the WWT ATC for testing and customer evaluation.
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