(^16) DESIGN WORLD — EE NETWORK 6 • 2019 eeworldonline.com | designworldonline.com
TEST & MEASUREMENT HANDBOOK
WI-FI 6 AND THE 6-GHZ BAND
It is important not to confuse Wi-Fi 6 and Wi-Fi in the 6-GHz band,
as these are two separate, but interconnected, topics.
Wi-Fi 6 is the Wi-Fi Alliance’s new consumer-friendly name
for the IEEE 802.11ax standard. The 802.11ac standard has also
been renamed Wi-Fi 5; 802.11n is now Wi-Fi 4. The purpose of
this new naming scheme is to make it easier for the general public
to identify device generations without remembering the complex
802.11 alphabet soup.
IEEE 802.11ax has been defined to operate in the 2.4-
GHz and 5-GHz bands, and many device manufacturers are
already shipping Wi-Fi 6 equipment operating in these bands.
Now the stage is set for operation from 5.925-7.125 GHz. Wi-Fi
6-compliant devices operating in the 6-GHz band could become
available as early as 2020.
Wi-Fi 6 is already a revolutionary standard as it introduces
orthogonal frequency-division multiple access (OFDMA). OFDMA
is a real disruptor in the way Wi-Fi operates because it allows
multiple users to transmit simultaneously. Unlike with OFDM,
the technology used for older Wi-Fi generations, OFDMA Wi-Fi
channel bandwidth (20, 40, 80 or 160 MHz) is divided amongst
multiple users who simultaneously transmit on smaller sub-
channels called resource units (RU). 802.11ax is big step toward
addressing network congestion. Its impact often gets compared to
upgrading from a single-lane road (OFDM) to a multi-lane freeway
(OFDMA).
But OFDMA only becomes effective with wide adoption of
Wi-Fi 6 technology in client devices and access points. Indeed,
each time a legacy device (11ac, 11n or older) transmits in
the network, the transmission reverts back to standard OFDM
mode with a single transmission occupying the entire spectrum.
Only Wi-Fi 6 devices are capable of participation in an OFDMA
transmission. The truth is that until most consumer devices employ
Wi-Fi 6, users may not notice much performance improvement
over older technologies.
On the other hand, the introduction of the 6-GHz band for
Wi-Fi use provides instant gratification for all Wi-Fi 6 users. With
enough spectrum to safely deploy 80-MHz or 160-MHz-wide
channels and green-field deployments alleviating concerns of
backward compatibility, the 6-GHz frequency band could become
the VIP Lounge for Wi-Fi 6 users, where high throughput rates and
congestion-free network access can be instantly achieved.
A DEEPER LOOK AT THE 6-GHZ FREQUENCY BAND
The 6-GHz frequency band, also called mid-band spectrum, spans
5.925 GHz to 7.125 GHz. It is divided into four bands:
UNII-5: 5925-6425 MHz (500 MHz)
UNII-6: 6425-6525 MHz (100 MHz)
UNII-7: 6525-6875 MHz (350 MHz)
UNII-8: 6875-7125 MHz (250 MHz)
The mid-band spectrum is currently for licensed users who have
deployed services in these frequencies. For example, users
include point-to-point microwave links and mobile TV pickups
at sporting events relaying signals back to a studio. There
are currently around 100,000 microwave links in the U.S. The
operators of these links are common carriers (AT&T, Verizon, etc.),
industrial and business entities (utilities, railroad, oil and gas) and
public safety agencies (safety, emergency services, transportation).
These incumbents have concerns about coexistence and
possible signal interference with unlicensed services. FCC rulings
will likely include mechanisms to mitigate interference from Wi-Fi
operation in the 6-GHz band, either by having devices operate
indoors only at low power levels or by having AFC (Automated
Frequency Coordination) mechanisms in place.
While these coexistence processes are still being finalized,
Wi-Fi chip and device makers are already planning to offer
products soon after the regulatory bodies grant their final
approval. The IEEE incorporated definitions for the new 6 GHz
frequency band channels in the latest draft of the 802.11ax
standard.
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The Unlicensed National Information Infrastructure (U-NII) radio band is part of the radio frequency
spectrum used by IEEE 802.11a devices and by many wireless ISPs. U-NII is an FCC regulatory domain for
5 GHz wireless devices. The European HiperLAN standard operates in same frequency band as the U-NII.
United States
European Union
5925
MHz
6425
MHz
6525
MHz
6875
MHz
7125
MHz
59 x 20 MHz channel
29 x 40 MHz channel
14 x 80 MHz channel
7 x 160 MHz channel
Mid-band spectrum roadmap
Litepoint — Test and Measurement HB 06-19.indd 16 6/10/19 1:48 PM
amelia
(Amelia)
#1