Huawei CloudCampus Network Wi-Fi 7
(802.11be)
Technology White Paper
Huawei CloudCampus Network Wi-Fi 7 (802.11be)
Technology White Paper
Abstract
Abstract
This white paper describes the development history of Wi-Fi, key Wi-Fi 7
(802.11be) technologies, and working principles in application scenarios. Also, this
document briefly introduces Huawei's Wi-Fi 7 products.
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Huawei CloudCampus Network Wi-Fi 7 (802.11be)
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Contents
Contents
Abstract ......................................................................................................................................i
1 Overview ...............................................................................................................................1
1.1 Wi-Fi Standard Development .................................................................................................................................... 1
1.2 Technical Advantages of Wi-Fi 7 ............................................................................................................................. 3
2 Key Technologies of Wi-Fi 7 ..............................................................................................4
2.1 802.11be Frame Structure .......................................................................................................................................... 4
2.2 6 GHz Network Discovery and Management ...................................................................................................... 5
2.2.1 In-Band 6 GHz AP Discovery .................................................................................................................................. 6
2.2.2 Out-of-Band 6 GHz AP Discovery ........................................................................................................................ 6
2.3 6 GHz and 320 MHz ..................................................................................................................................................... 7
2.4 4096-QAM ........................................................................................................................................................................ 9
2.5 Multi-Link ......................................................................................................................................................................... 9
2.6 MRU .................................................................................................................................................................................. 11
2.7 Enhanced TWT (R-TWT) ........................................................................................................................................... 12
2.8 Enhanced DCM ............................................................................................................................................................. 14
2.9 Triggered TXOP Sharing ............................................................................................................................................ 15
2.10 802.11az High-Precision Positioning .................................................................................................................. 16
2.11 802.11ba Deep Power Saving ............................................................................................................................... 17
3 Wi-Fi 7 Application Scenarios......................................................................................... 22
3.1 Using Wi-Fi 7 to Build 10GE Office Networks .................................................................................................. 22
3.2 Using Wi-Fi 7 to Build 10GE Production Networks ......................................................................................... 23
4 Huawei Wi-Fi 7 and Products ......................................................................................... 24
4.1 Huawei Wi-Fi 7 ............................................................................................................................................................. 24
4.2 Huawei Wi-Fi 7 Products .......................................................................................................................................... 24
A Acronyms and Abbreviations ......................................................................................... 26
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1 Overview
1
Overview
1.1 Wi-Fi Standard Development
In 1990, the Institute of Electrical and Electronics Engineers (IEEE) established the
802.11 working group to standardize wireless local area networks (WLANs). After
years of development, 802.11 has gradually become a series of standard protocols.
The initial version of IEEE 802.11 defines the MAC layer and physical layer (PHY).
It was completed in 1997, and therefore is also called 802.11-1997. The industry
finally adopts 802.11 as the WLAN standard, instead of other complex
technologies that use centralized access protocols (such as HyperLAN). After that,
the WLAN standard has been evolving.
802.11n (Wi-Fi 4)
The IEEE 802.11 working group established a High Throughput (HT) study group
(SG) in 2002 to formulate a next-generation standard, and officially issued the
802.11n standard based on multiple-input multiple-output (MIMO) and
orthogonal frequency division multiplexing (OFDM) in 2009. The 802.11n standard
has the following characteristics:
●
Supports a maximum of four spatial streams.
●
Defines single-user (SU) beamforming to improve signal receiving quality.
●
Delivers a speed of 300 Mbps at the 20 MHz channel bandwidth, and up to
600 Mbps at the 40 MHz channel bandwidth.
●
Incorporates 802.11e to improve real-time service quality, requiring 802.11ncompliant devices to support 802.11e features.
802.11ac (Wi-Fi 5)
With the rapid growth of multimedia services, people's requirements for data
transmission rates increase exponentially. There
As such, the IEEE 802.11 working group officially issued the 802.11ac standard in
2014, which is also known as the Very High Throughput (VHT) standard. The
802.11ac standard has the following characteristics:
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1 Overview
●
Increases the number of spatial streams from 4 in 802.11n to 8.
●
Supports 160 MHz channel bandwidth, and delivers a maximum data rate of
6933.33 Mbps.
●
Defines downlink MIMO (DL MU-MIMO) technology, allowing for downlink
multi-user concurrent transmission.
802.11ax (Wi-Fi 6)
For high-density and high-concurrency scenarios, IEEE officially issued the nextgeneration 802.11ax standard in 2019, which is also known as the High Efficiency
Wireless (HEW) standard. The 802.11ac standard has the following characteristics:
●
Uses orthogonal frequency division multiple access (OFDMA) technology and
supports narrower subcarrier spacing to improve the robustness and
throughput of wireless transmission in indoor and outdoor scenarios.
●
Introduces uplink MU-MIMO (UL MU-MIMO) technology to further improve
the throughput and service quality in high-density user scenarios.
802.11be (Wi-Fi 7)
With the booming development of emerging applications such as mobile Internet,
fully-wireless office, and VR/AR home immersive entertainment, people's
requirements for wireless access bandwidth are gradually upgraded from 1000
Mbps to 10 Gbps. In 2023, IEEE released the 802.11be standard draft, which is also
known as the Extremely High Throughput (EHT) standard. The 802.11be standard
has the following characteristics:
●
Supports the 6 GHz frequency band that provides 1.2 GHz (in FCC countries
such as the United States) or 480 MHz (Europe) super-large and clean
spectrum. The 802.11be standard increases channel bandwidth from 160 MHz
to 320 MHz, and supports a maximum data rate of up to 23.05 Gbps on the 6
GHz frequency band.
●
Introduces multi-link technology to bundle multiple radios, such as 5 GHz + 6
GHz and 5 GHz-L + 5 GHz-H, greatly increasing the bandwidth.
Figure 1-1 shows the differences of 802.11 protocols.
Figure 1-1 Comparison of 802.11 protocols
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1.2 Technical Advantages of Wi-Fi 7
Looking back on the evolution of standards, Wi-Fi 7 supports the 6 GHz spectrum
on the basis of 2.4 GHz and 5 GHz. Wi-Fi 7 is technically upgraded to provide
higher bandwidth, lower latency, and stronger access capability.
Higher throughput
Wi-Fi 7 uses higher bandwidth of 320 MHz, higher-order modulation of 4096QAM, and Multi-Link. At the same conditions, the rate of Wi-Fi 7 is 2.4 times that
of Wi-Fi 6. Based on Draft 4.0 released in July 2023, Wi-Fi 7 can achieve a
theoretical peak rate of up to 30 Gbps, almost three times that of Wi-Fi 6.
Therefore, Wi-Fi 7 can support higher-throughput applications, such as AR/VR, 4K
and 8K video streaming, and cloud computing.
Lower latency
Wi-Fi 7 can operate on the 2.4 GHz, 5 GHz, and 6 GHz frequency bands. It uses
Multi-Link Operation (MLO) technology to flexibly schedule resources on different
frequency bands and supports the setup of multiple wireless links between STAs
and APs. As such, the communication link can be flexibly selected based on the
specific scenario to avoid poor-quality channels. Also, Wi-Fi 7 introduces Multiple
Resource Unit (MRU) technology, which greatly improves channel resource
efficiency and reduces the waiting latency on the air interface. With these new
features, Wi-Fi 7 can ensure lower latency and easily cope with applications that
demand high bandwidth and low latency.
Stronger access capability
Compared with Wi-Fi 6 devices operating on 2.4 GHz and 5 GHz frequency bands,
Wi-Fi 7 devices support a new frequency band and therefore have stronger access
capabilities in the same scenario. Wi-Fi 7 supports 4096-QAM and enhanced
MIMO capabilities, allowing more STAs to access the Wi-Fi 7 network in highdensity scenarios. Additionally, MRU technology enables more efficient spectrum
resource utilization and avoids resource waste caused by air interface competition.
Multi-AP Coordinated Spatial Reuse (CoSR) intelligently adjusts channels and
power of neighboring APs in the continuous networking to reduce co-channel
interference, ensure wireless network experience of STAs, and greatly improve the
concurrency capability and performance of APs in high-density scenarios.
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2 Key Technologies of Wi-Fi 7
Key Technologies of Wi-Fi 7
2.1 802.11be Frame Structure
The 802.11be standard evolves based on the frame format of 802.11ax.
Specifically, 802.11ax defines HE SU and HE MU as two independent frame
formats, while 802.11be integrates the two frame formats and newly defines an
EHT MU PHY protocol data unit (PPDU). This PPDU can be used for both SU and
MU transmission. Similar to the HE trigger-based (TB) PPDU in 802.11ax,
802.11be also defines the EHT TB PPDU. Figure 2-1 shows the frame format.
Figure 2-1 EHT PPDU format
The universal signal (U-SIG) field is introduced IN 802.11be. Different from the
SIG design of Wi-Fi 6 and earlier versions, the U-SIG field in 802.11be contains
PHY version information and is forward compatible with various possible frame
formats in the future, simplifying the frame format identification process of the
receiver. The Disregard and Validate fields are added to the U-SIG, based on which
the receiver can determine whether it has the receiving capability. If not, the
receiver can terminate the receiving capability in advance, improving the
adaptation efficiency of PHY access. Additionally, information carried in the U-SIG
field further includes the uplink/downlink indication, TXOP, BSS Color, and
bandwidth fields. Figure 2-2 and Figure 2-3 show the definitions of the U-SIG
fields in the EHT MU PPDU and EHT TB PPDU, respectively.
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Figure 2-2 EHT MU PPDU U-SIG
Figure 2-3 EHT TB PPDU U-SIG
The EHT MU PPDU defines the EHT SIG field, which provides a basis for unifying
the SU and MU frame formats. The EHT SIG field includes a common field and a
user field. The common field carries common information about the PPDU, and
the user field carries independent information about each user, such as the MCS,
the number of spatial streams (NSS), and the coding scheme of the user. Figure 24 shows the definition of the EHT-SIG field in the EHT MU PPDU transmitted in
non-OFDMA SU scenarios.
Figure 2-4 EHT-SIG in the EHT MU PPDU transmitted in non-OFDMA SU scenarios
2.2 6 GHz Network Discovery and Management
In most cases, Wi-Fi station (STA) typically detects access points (APs) by using
active scanning. Traditionally, a STA client sends a Probe Request frame on the 2.4
GHz and 5 GHz channels to discover an AP. On the 6 GHz frequency band
supported in 802.11be, there are 59 channels, which means active scanning on
each channel will take a lot of time. If passive listening is used, it takes more than
5.9 seconds to complete listening to all 6 GHz channels, which is unacceptable in
a roaming scenario.
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To address the preceding issues, 802.11be provides two new mechanisms: in-band
6 GHz AP discovery and out-of-band 6 GHz AP discovery.
2.2.1 In-Band 6 GHz AP Discovery
In-band 6 GHz AP discovery can be implemented using the following methods:
●
Passively listening to fast initial link setup (FILS) Discovery frames
●
Passively listening to broadcast Probe Response frames
●
Proactively scanning preferred scanning channels (PSCs)
Similar to broadcast Probe Response frames, FILS frames are sent at an interval of
20 time units (TUs, 1 TU = 1.024 ms). The difference between the two types of
frames is that a FILS frame is a condensed frame, containing only the BSSID, short
SSID, and PSC channel ID, while a Probe Response frame contains all the same
detailed information as a Beacon frame.
Figure 2-5 FILS Discovery/Probe Response frames sent at an interval of 20 TUs
The 6 GHz channels are categorized as PSC or non-PSC channels. For a 20 MHz
channel on the 6 GHz frequency band, the center frequency of the channel
(channel start frequency 5950 MHz – 55 + 80 x n, in MHz) ( n = 1, ..., 15) is the
PSC. The complete list of all the 6 GHz PSCs is 5, 21, 37, 53, 69, 85, 101, 117, 133,
149, 165, 181, 197, 213, and 229.
STAs that support the 6 GHz frequency band can broadcast Probe Request frames
on these channels. Devices operating on the PSCs can be discovered more quickly.
2.2.2 Out-of-Band 6 GHz AP Discovery
Most chips of 6 GHz STAs also support 2.4 GHz and 5 GHz functions, so these
STAs can perform channel scanning on the 2.4 GHz and 5 GHz frequency bands.
During 2.4 GHz and 5 GHz channel scanning of a Wi-Fi 7 STA, a Wi-Fi 7 tripleradio AP (2.4 GHz + 5 GHz + 6 GHz) can notify this STA of existing 6 GHz radio
information on the AP.
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As shown in the following figure, when an AP operates on the 2.4 GHz or 5 GHz
frequency band, it can carry the Reduced Neighbor Report (RNR) field in Beacon
and Probe Response frames to announce the existence of 6 GHz signals.
2.3 6 GHz and 320 MHz
In April 2020, the Federal Communications Commission (FCC) decided to open up
the 6 GHz frequency band ranging from 5925 MHz to 7125 MHz for license-free
applications. Compared with the 2.4 GHz and 5 GHz frequency bands, the new 6
GHz frequency band has various advantages.
The 6 GHz frequency band has wider spectrum resources. It has a total spectrum
of 1200 MHz bandwidth, which can accommodate seven 160 MHz channels,
fourteen 80 MHz channels, twenty-nine 40 MHz channels, or fifty-nine 20 MHz
channels. The 6 GHz frequency band provides even more than spectrum resources
than the 2.4 GHz and 5 GHz frequency bands together provide.
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Figure 2-6 Channel distribution on the 2.4 GHz, 5 GHz, and 6 GHz frequency bands
The 6 GHz frequency band suffers less interference. The usage of 2.4 GHz and 5
GHz frequency bands (such as Bluetooth, ZigBee, and radar) is high, the number
of devices is large, and the channel congestion is severe. As a newly developed
frequency band, the number of devices and usage of 6 GHz frequency bands are
much lower than those of 2.4 GHz and 5 GHz frequency bands, and the
interference is low, the channel environment is better.
Thanks to richer spectrum resources on the 6 GHz frequency band, ultra-large
bandwidth transmission becomes more feasible. Wi-Fi 7 increases the PPDU
transmission bandwidth to 320 MHz for the first time. For flexible use of the
bandwidth, Wi-Fi 7 further supports joint scheduling of discontinuous spectrum
blocks of 160+160 MHz, 160+80 MHz, and 240+180 MHz, this increases flexibility
of spectrum utilization for large-bandwidth transmission. With the same number
of streams and code modulation, the throughput can be doubled. The maximum
transmission bandwidth of Wi-Fi 7 is twice that of Wi-Fi 6.
Table 2-1 Channel bandwidths supported by different 802.11 protocols
Protocol
Supported Channel Bandwidth
802.11
20 MHz
802.11a/b/g
20 MHz
802.11n
20 MHz and 40 MHz
802.11ac
20 MHz, 40 MHz, 80 MHz, 80+80 MHz, and 160 MHz
802.11ax
20 MHz, 40 MHz, 80 MHz, 80+80 MHz, and 160 MHz
802.11be
20 MHz, 40 MHz, 80 MHz, 80+80 MHz, 160 MHz, 160+80
MHz, 240 MHz, 160+160 MHz, and 320 MHz
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2.4 4096-QAM
In 802.11ax, the highest-order quadrature amplitude modulation (QAM) is 1024QAM, allowing each symbol to transmit 10-bit data (2^10 = 1024). The 802.11be
standard supports 4096-QAM, allowing each symbol to transmit 12-bit data (2^12
= 4096). Therefore, compared with 802.11ax, 802.11be increases the data
throughput by 20% under the same bandwidth and same NSS.
Figure 2-7 1024-QAM vs. 4096-QAM
However, it should be noted that higher-order QAM modulation means a denser
constellation point distance. This imposes higher requirements on the error vector
magnitude (EVM) and transmit/receive processing capabilities of the receiver for
correct demodulation. The EVM is used to quantify the performance of a radio
receiver or transmitter in terms of modulation accuracy.
2.5 Multi-Link
Figure 2-8 Multi-Link supported in Wi-Fi 7
Even though STAs in compliance with Wi-Fi 6 and earlier protocols support
multiple frequency bands, each of them can set up only one link with the peer
end. Wi-Fi 7 defines a multi-link device (MLD), allowing multiple links to be set up
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between an AP and a STA, significantly improving throughput and reducing
latency, as shown in Figure 2-8.
The MLD includes a plurality of independent PHYs. Wi-Fi 7 introduces a MAC that
can coordinately manage each independent PHY. This MAC capability is defined as
the multi-link operation (MLO), which resolves issues in multi-link aggregation,
channel access, data transmission, etc.
In the MLO of Wi-Fi 7, channel access can be classified as asynchronous or
synchronous mode.
1.
Asynchronous mode
Two radios work independently and can transmit data asynchronously.
Figure 2-9 Asynchronous channel access mode
2.
Synchronous mode
Two radios need to receive or transmit signals at the same time, and cannot
transmit data asynchronously.
Figure 2-10 Synchronous channel access mode
The MLO enables data flows to be sent on multiple Over-The-Air (OTA) channels
to an MLD. Data access modes are as follows:
1.
Peak transmission mode: improves the peak throughput of a single user and
doubles the peak throughput at dual bands.
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2.
Adaptive redundancy transmission mode: reduces the latency and improves
link reliability for some STAs.
3.
Fast link switching transmission mode: performs initial transmission, fast
retransmission, and cross-link transmission, reducing latency by 50% at most
and improving reliability.
2.6 MRU
According to OFDMA technology introduced in Wi-Fi 6, frequency resources are
allocated based on resource units (RUs). Wi-Fi 6 supports seven types of RUs:
26/52/106/242/484/996/2x996 tones. To further improve the flexibility of
spectrum resource scheduling, Wi-Fi 7 introduces MRU technology, which can
allocate multiple RUs to a single user. Figure 2-11 shows the MRU combination of
52+26 tones for 20 MHz bandwidth.
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Figure 2-11 MRU combination of 52+26 tones in an OFDMA 20 MHz EHT PPDU
The combinations of seven types of RUs are complex. As such, Wi-Fi 7 restricts the
types of MRUs by classifying them as small size MRUs or large size MRUs, as
described in Table 2-2.
Table 2-2 MRU classification
RU Type
RU Combination
Bandwidth (MHz)
Small size MRU
26+106 tones
20/40/80/160/320
26+52 tones
20/40/80/160/320
242+484 tones
80/160/320
484+996 tones
160/320
2x996 tones
160/320
242+484+996 tones
160 (only for non-OFDMA)
484+2x996 tones
320
3x996 tones
320
484+3x996 tones
320
4x996 tones
320
Large size MRU
2.7 Enhanced TWT (R-TWT)
The target wake time (TWT) allows an AP and STAs to set up TWT service periods
(SPs) and negotiate and define specific media access time. The STAs wake up
within the SPs to transmit packets. With the TWT, STAs sleep all the time except
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during TWT SPs, thereby reducing power consumption. In addition, STAs access
the channel at different time, reducing contention collisions.
In Wi-Fi 6, APs must support unicast TWT and can support broadcast TWT, while
STAs can support unicast TWT. Wi-Fi 7 defines a cross-link TWT mechanism for
multi-link transmission, and defines restricted TWT (R-TWT) for transmission of
low-latency traffic.
The R-TWT allows APs to use enhanced channel access and resource reservation
mechanisms to provide more predictable latency, lower worst-case latency, and
lower jitter, and provide higher reliability for transmission of latency-sensitive
traffic.
The setup process of R-TWTs in Wi-Fi 7 is similar to that of broadcast TWTs in WiFi 6. The only difference is that the TWT setup frame includes a broadcast TWT
element containing the Restricted TWT Parameter Set field.
Rules of channel contention in R-TWT SPs
●
An extremely high throughput (EHT) STA that supports R-TWT must end its
TXOP before the start of an R-TWT SP.
●
The Quiet element defines an interval of 1 TU at the start of each R-TWT SP.
In this interval, the STA keeps quiet and no legacy STA can access the channel
in R-TWT SPs.
●
For non-AP EHT STAs, the quiet interval can be ignored.
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2.8 Enhanced DCM
Wi-Fi 7 can work on the 6 GHz frequency band in addition to the 2.4 GHz and 5
GHz frequency bands, but has weaker coverage capabilities on the 6 GHz
frequency band. To increase the coverage distance on the 6 GHz frequency band,
Wi-Fi 7 introduces the DCM(Dual Carrier Modulation)+ DUP( Duplicate) mode,
which is also called EHT-DUP mode. The EHT-DUP mode is signaled using MCS14.
This mode is used in compliance with the following conditions:
1.
It is applicable only on the 6 GHz frequency band.
2.
It is only used with bandwidths 80 MHz, 160 MHz, and 320 MHz, and without
preamble puncturing.
3.
It is applicable only for single-user transmission.
4.
It is applicable only in conjunction with BPSK-DCM modulation, bit rate 1/2,
and LDPC encoding.
5.
The number of spatial streams is 1.
In EHT-DUP mode, frequency-domain duplication occurs after BPSK-DCM
modulation, thereby obtaining extra diversity gains. To reduce the peak-toaverage ratio during the duplication, some subcarriers need to be reversed. Figure
2-12 shows the working principle of the EHT-DUP mode at 80 MHz.
Figure 2-12 Working principle of the EHT-DUP mode at 80 MHz
x0 is the initial constellation symbol obtained after LDPC tone mapping. After
DCM modulation is performed, x1 is obtained. Then, x0 is duplicated and reversed
to DUP DCM_L, and x1 is duplicated to DUP DCM_H. From the foregoing steps, it
can be learned that:
●
When the bandwidth is 80 MHz, 484-tone RUs are duplicated again after
BPSK-DCM modulation.
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●
When the bandwidth is 160 MHz, 996-tone RUs are duplicated again after
BPSK-DCM modulation.
●
When the bandwidth is 320 MHz, 2 x 996-tone RUs are duplicated again after
BPSK-DCM modulation.
2.9 Triggered TXOP Sharing
In addition to the power saving functionality called TWT in Wi-Fi 6, Wi-Fi 7 also
supports the triggered transmission opportunity (TXOP) sharing function to
further save power. This function allows an AP to allocate a portion of time within
an obtained TXOP to STAs for transmitting data, so that the STAs do not need to
wake up in the next SP.
The AP allocates a portion of time to a single STA by using a specific field in an
MU-RTS Trigger frame, and the STA transmits data within the allocated portion of
time.
1.
Triggered single-user scheduling needs to be accurately controlled on the AP
side. Data needs to be reported through BSR to calculate the length (which
may be inaccurate) and other parameter values. In contrast, triggered TXOP
sharing does not require this procedure. After a portion of time is allocated to
a STA, the STA determines the amount of data to be sent, which can release
the complexity on the AP side.
2.
The STA can flexibly transmit data in P2P or UL mode within the allocated
time. In addition, instead of returning TB PPDUs in the SIFS, the STA can
prepare uplink packets to be sent in advance.
The triggered TXOP sharing function enables STAs to use the UL mode or P2P
mode, which is specified by the original GI And HE-LTF Type field. (The AP ends
the TXOP in advance.)
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2.10 802.11az High-Precision Positioning
802.11az, referred to as Next Generation Positioning (NGP), is replacing signal
strength-based positioning technologies that are currently widely used. It defines
modifications to the PHY and medium access control (MAC) layer, and uses Fine
Timing Measurement (FTM) to determine STAs' absolute and relative locations
more precisely. 802.11az reduces power consumption, increases channel
utilization, and incorporates security features. It is scalable to high-density
deployment environments.
In FTM, the round trip time (RTT) is used to calculate the distance between the
initiating STA (ISTA) and responding STA (RSTA). Figure 2-13 shows the frame
interaction process between an ISTA and an RSTA. After the ISTA sends an NDP
Announcement frame to the RSTA and receives an ACK frame, it sends an I2R
NDP frame to the RSTA and records the Time of Departure (TOD) timestamp as
t1. After the RSTA receives the I2R NDP frame, it records the Time of Arrival
(TOA) timestamp as t2. Then, it sends an R2I NDP frame to the ISTA and records
the TOD timestamp as t3. After receiving the R2I NDP frame, the ISTA records the
TOA timestamp as t4. The RTT is calculated as follows: RTT = (t2 – t1) + (t4 – t3).
The distance between the ISTA and RSTA can be the speed of light multiplied by
the time of flight (ToF) (that is, RTT/2).
Figure 2-13 Frame interaction process
Due to the synchronization precision, the recorded timestamps t2 and t4 may be
deviated. The first-path latency or phase offset needs to be used on the ISTA and
RSTA to compensate for the deviation, improving the ranging precision. In
addition, in Wi-Fi 7, the signal bandwidth can be extended to 320 MHz, and
ranging precision may be further improved.
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Figure 2-14 802.11az network example
As shown in the preceding figure, the 802.11az network consists of one STA and
multiple APs. At least three APs are required to estimate the STA's position. In this
example, the STA is the ISTA, and the three APs are RSTAs. After the distances
between the ISTA and RSTAs are obtained by using aforementioned method, the
ISTA's position can be obtained by using the trilateral positioning method. In this
method, the ISTA needs to set up FTM sessions with at least three RSTAs that are
not in a same straight line to obtain relative distances between the ISTA and
RSTAs. Draw a circle with each distance as the radius. The ISTA is positioned at
the intersection point of the three circles, as shown in Figure 2-15.
Figure 2-15 Trilateral positioning method
2.11 802.11ba Deep Power Saving
802.11ba, referred to as Wake-Up Radio (WUR), enables a wake-up receiver with
ultra-low power consumption to listen on wake-up packets when the
communications module of a communications station is in the deep sleep state,
thereby greatly saving power. WUR has the following characteristics:
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1.
After receiving a wake-up packet, the wake-up receiver wakes up the
communications module to receive and send data and signaling.
2.
The wake-up packet is simply modulated using on-off keying (OOK) and the
channel is narrow, so that the power consumption and costs of the wake-up
receiver can be greatly reduced.
The following figure shows the working diagram of WUR.
Figure 2-16 Working diagram of WUR
The WUR PHY supports two PPDU formats: WUR Basic PPDU and WUR FDMA
PPDU. The PPDU consists of the L-STF, L-LTF, L-SIG, BPSK-Mark1, BPSK-Mark2,
WUR-Sync, and WUR-Data fields.
The L-STF, L-LTF, L-SIG, BPSK-Mark1, and BPSK-Mark2 fields are processed
through OFDM. They are broadband signals, and are used to protect WUR
narrowband signals and distinguish WUR narrowband signals from another Wi-Fi
frames.
The WUR-Sync and WUR-Data fields are narrowband signals (about 4 MHz). The
WUR-Sync field is used for time synchronization, automatic gain control (AGC),
and data rate indication. The WUR-Data field carries MAC layer data that needs to
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be transmitted by WUR. The WUR-Sync and WUR-Data fields are modulated using
OOK. When bit 1 is transmitted, a fixed waveform (which can be customized) is
sent in the OOK symbol. When bit 0 is transmitted, no waveform is sent in the
OOK symbol. The receiver can demodulate the data to be sent by detecting
whether the received signal has a power. The receiving process is simple, which
further improves the power saving effect. The following figure shows how an OOK
waveform is generated.
WUR supports two data rates: High Data Rate (HDR) 250 kbps and Low Data Rate
(LDR) 62.5 kbps. The two rates are indicated by different bit sequences in the
WUR-Sync field.
For the LDR, the WUR-Sync field has 64 bits in total, and is constructed by
concatenating two copies of the following W sequence, where each bit is mapped
to a 2 μs HDR MC-OOK symbol.
For the HDR, the WUR-Sync field consists of the following 32-bit
sequence
(lower bits on the left), where each bit is mapped to a 2 μs HDR MC-OOK symbol.
To generate a 20 MHz HDR OOK waveform, 13 subcarriers in the middle of 64point frequency-domain data are used. After being transformed to the time
domain using Fast Fourier Transform (IFFT), the first 32 time domain sampling
points are used to obtain a 2 μs WUR waveform. 802.11ba does not has a strict
restriction on the data loaded on the 13 valid subcarriers. The following table
provides example sequences for your reference.
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Table 2-3 Examples of MC OOK frequency-domain data in HDR mode
An LDR OOK waveform is generated similarly. The difference is that the duration
is 4 μs. The following table lists samples of OOK frequency-domain sequences in
LDR mode.
Table 2-4 Examples of MC OOK frequency-domain data in LDR mode
The WUR-Data field supports 1/2 and 1/4 encoding bit rates. The following table
lists the encoding modes.
Table 2-5 WUR-Data code mapping table
Input Bit
Encoded Bits (LDR)
Encoded Bits (HDR)
0
1010
10
1
0101
01
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After the encoded data is mapped to a WUR OOK waveform, a random cyclic shift
is added to the waveform, depending on the antennas and data symbols. The
WUR OOK waveform has now been processed.
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3 Wi-Fi 7 Application Scenarios
Wi-Fi 7 Application Scenarios
3.1 Using Wi-Fi 7 to Build 10GE Office Networks
In the enterprise office environment, wireless access is replacing wired access.
Office areas are fully covered by Wi-Fi. No wired network ports are provided by
desks any more. The office environment is more open and intelligent. In addition,
high-bandwidth services, including enterprise cloud desktop office, telepresence
conference, and 4K video, will be migrated from wired to wireless networks.
Likewise, new technologies such as VR/AR and virtual assistant, will be directly
deployed based on wireless networks. New application scenarios pose higher
requirements on enterprise WLANs.
The next-generation Wi-Fi 7 standard was released, hitting yet another milestone
in the Wi-Fi history. Wi-Fi 7 can work on the 6 GHz frequency band for the first
time in the past 20 years. The capacity of Wi-Fi 7 networks has been significantly
improved, leading indoor wireless communications into the 10 Gbps era. In
addition, the multi-user concurrency performance is also greatly improved,
enabling the network to maintain excellent service capabilities in high-density
access and heavy-load scenarios. The following are some example scenarios:
1.
Enterprise office scenario: A single AP supports 30 channels of HD
conferences and Gbps-level download, ensuring no frame freezing during
online video conferences. In addition, download and upload services such as
email download and cloud-local data synchronization can obtain a Gbps
experience rate.
2.
VR classroom scenario: Through proper channel planning and AP deployment
(generally three APs are deployed), all-wireless access (30–40 VR devices) can
be provided for a VR classroom, providing a total capacity of over 5 Gbps.
With the further development of information technologies and enterprise
digitalization, more efficient and intelligent collaboration and office modes may
come into being in future enterprise office scenarios, for example, virtual humans,
AR-assisted office, and online AI computing. Wi-Fi 7 is fully prepared for this trend
and provides ultra-broadband 10GE office networks.
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3.2 Using Wi-Fi 7 to Build 10GE Production Networks
On industrial production networks, services related to wireless communication are
classified into control and collection services and high-bandwidth transmission
services.
1.
Control and collection services fall into the following types:
Remote control services: These services have certain requirements on network
latency and network bandwidth. For example, remote video control services
require that the latency be less than or equal to 20 ms. In addition, network
bandwidth assurance must be provided based on the definition of remote
control videos.
Onsite control services: include production line PLC, production line I/O, and
device motion control services. The network traffic of these services is
generally periodically transmitted. These services have differentiated
requirements for key indicators such as network latency and packet loss rate
based on control objects. The network latency is generally less than 10 ms.
AGV control services: Services such as AGV navigation and remote diagnosis
and maintenance guidance based on wireless networks require a latency of
about 50 ms and do not allow second-level network interruption.
Sensor collection services: include sensor information collection and video
detection and collection. These services typically require that the packets sent
for environment sensing and data collection be 100 ms to 10s at a rate of 100
kbps.
The remote control, AGV control, and sensor collection services can be carried
over Wi-Fi 7 networks with a 10 ms RTT. Onsite control services can be carried
over wireless networks or not based on customer requirements.
2.
High-bandwidth transmission services fall into the following types:
Automated optical inspection (AOI): AOI is an automatic optical inspection
technology used to inspect the quality of electronic components and printed
circuit boards (PCBs) in industrial production scenarios. A high-resolution
optical imaging system takes photos of an object to be detected, and then
analyze the photos using the image processing algorithm to detect quality
defects and defective products. AOI requires a high-speed and stable wireless
network to transmit image data to ensure accurate and real-time detection.
Device program download: Commercial software of automobiles and
electronic devices are upgraded at the end of the production phase, which
consumes a large amount of bandwidth. Therefore, high-bandwidth wireless
connections are required.
These services can be implemented through wireless connection capabilities
of Wi-Fi 7 10GE production networks.
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4 Huawei Wi-Fi 7 and Products
Huawei Wi-Fi 7 and Products
4.1 Huawei Wi-Fi 7
Huawei has been actively participating in Wi-Fi standards development, making
continuous contributions to the future of the entire industry. Dr. Osama of Huawei
served as the chairman of the Wi-Fi 6 standard, and Dr. Edward, as the technical
editor of the Wi-Fi 7 standard core team, participated in the formulation and
release of the Wi-Fi 7 standard throughout the entire process. Over the years,
Huawei has been committed to investing huge manpower and material resources
in Wi-Fi standards formulation. According to a public report released in 2021,
Huawei ranked No. 1 in the world in terms of the number of Wi-Fi 7 standards.
Huawei also ranked No. 1 in the world In terms of the total number of Wi-Fi 4 to
Wi-Fi 7 standards. Therefore, with a large number of innovative technologies and
patents developed during the formulation of standards over the years, Huawei is a
leader in Wi-Fi industry standards.
In addition, Huawei launched the first enterprise-grade Wi-Fi 7 AP in 2022.
Huawei actively explores innovative solutions centered on customer experience in
various scenarios. Based on standard technologies, Huawei continuously develops
unique innovation capabilities to meet customer requirements in various
application scenarios and offer ultimate network experience to users in various
industries.
4.2 Huawei Wi-Fi 7 Products
In HUAWEI CONNECT 2022, Huawei launched the industry's first enterprise-grade
Wi-Fi 7 AP AirEngine 8771-X1T. This Wi-Fi 7 AP uses an innovative hardware
architecture, adopts advanced Wi-Fi technologies such as 4096-QAM and multilink operation (MLO), and has built-in dynamic-zoom smart antennas, providing
18.67 Gbps ultra-high bandwidth and less than 2 ms ultra-low latency.
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Figure 4-1 Industry's first enterprise-grade Wi-Fi 7 AP - AirEngine 8771-X1T
Parameter
Description
Device rate
18.67 Gbps
(1.376 Gbps + 5.765 Gbps + 11.53 Gbps)
Radios
4x4 @ 2.4 GHz (40 MHz)
4x4 @ 5 GHz (160 MHz)
4x4 @ 6 GHz (320 MHz)
Antennas
Built-in dynamic-zoom smart antennas
Ports
2 x 10GE electrical ports (supporting PoE HSB), 1 x SFP+
port (supporting hybrid cables, 300 m PoE++)
IoT expansion
Built-in BLE 5.2
External USB
Power supply
DC: 48 V ± 10%
PoE: 802.3bt
In the future, Huawei will launch more Wi-Fi 7 products for large enterprise office,
education, and manufacturing fields, offer Wi-Fi 7 APs for all scenarios, monetize
innovative Wi-Fi 7 technologies, and provides high-bandwidth, low-latency, and
high-reliability wireless communication for innovative application scenarios of
enterprises such as metaverse and XR remote collaboration, helping enterprises
enter the high-quality 10GE campus era.
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A
A Acronyms and Abbreviations
Acronyms and Abbreviations
Acronym/Abbreviation
Full Name
AP
Access Point
AC
Access Control
WAC
WLAN Access Controller
BA
Block Ack
CCA
Clear Channel Assessment
CSMA/CD
Carrier Sense Multiple Access/Collision Detection
CO-OFDMA
Coordinated Orthogonal Frequency Division Multiple Access
DCM
Dual Carrier Modulation
OTA
Over-The-Air
MLO
Multi-Link Operation
MRU
Multiple Resource Unit
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