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By Powered By SmileMbb | 10 November 2021 | 1 Comments

What is the Wi-Fi6(802.11ax)?


Wi-Fi 6 is short for the next-generation 802.11ax standard. With the evolution of the Wi-Fi standard, WFA chose to rename Wi-Fi with a numeric serial number in order to facilitate Wi-Fi users and device manufacturers to easily understand the Wi-Fi models that their devices are connected to or supported. On the other hand, the next-generation naming method is also chosen to better highlight the major advances in Wi-Fi technology. It provides a large number of new features, including increased throughput and faster speeds, and support for more concurrent connections. According to the WFA announcement, the current Wi-Fi names correspond to the following 802.11 technical standards:
 
 
 
Year published 802.11 Standards Frequency bands Renaming
2009 802.11n 2.4 GHz or 5 GHz Wi-Fi 4
2013 802.11ac wave1 5 GHz  
 Wi-Fi 5
 
2015 802.11ac wave2 5 GHz
2019 802.11ax 2.4 GHz or 5 GHz Wi-Fi 6
 
Table 1 802.11 standards and new names
 
Like every 802.11 standard released in the past, 802.11ax will also be compatible with the previous 802.11ac/n/g/a/b standard. Old terminals can also seamlessly access the 802.11ax network.
 
How fast is Wi-Fi 6?
4G is synonymous with high speed of mobile networks. Similarly, Wi-Fi 6 is Synonym of high speed of wireless LAN. How high speed comes from is determined by the following factors.

Calculation formula:

Machine rate = number of spatial streams*1/(Symbol+GI)*coding method*code rate*number of effective sub-carriers



(1) The number of spatial streams
The spatial flow is actually the antenna of the AP. The more the number of antennas, the greater the throughput of the whole machine. Just like the lanes of a highway, 8-lane will definitely carry more traffic than four lanes.
 
 
  802.11a/g 802.11n 802.11ac 802.11ax
Single radio
Maximum spatial flow
 
1
 
4
 
8           
 

Table 2 The number of spatial streams corresponding to different 802.11 standards

(2)Symbol and GI

Symbol is the transmission signal in the time domain, and a certain gap (GI) between adjacent symbols is required to avoid interference between symbols. Just like China's high-speed rail, each train is equivalent to a symbol, and there must be a time gap between two trains from the same station, otherwise the two trains may collide. The gaps under different Wi-Fi standards are also different. Generally speaking, when the transmission speed is faster, the GI needs to be increased appropriately, just like the departure time gap between two 350KM/h high-speed trains on the same lane is larger than the 250KM/h high-speed train.

 
  Before 802.11ac 802.11ax
Symbol 3.2 us 12.8 us
Short GI 0.4 us /
GI 0.8 us 0.8 us
2*GI / 1.6 us
4*GI / 3.2 us
 
Table 3 Symbol and GI data corresponding to 802.11 standard

(3) Coding method

The coding method is the modulation technology, that is, the number of bits that can be carried in a symbol. From Wi-Fi 1 to Wi-Fi 6, every time the modulation technology is improved, the rate of each spatial stream can be increased by at least 20%.

 
  802.11a/g 802.11n 802.11ac 802.11ax
Highest order modulation 64 QAM 64 QAM 256 QAM 1024 QAM
Number of bit /Symbol 6 6 8 10
 
Table 4 QAM corresponding to 802.11 standard
 
(4) Bit rate

Theoretically, it should be transmitted losslessly according to the encoding method, but the reality is not so rosy. Some information codes for error correction need to be added during transmission, and redundancy is exchanged for high reliability. The code rate is the ratio of the actual data code to the theoretical value after the error correction code is excluded.

 
Scheme Modulation 802.11a/g 802.11n 802.11ac 802.11ax
MCS0 BPSK 1/2 1/2 1/2 1/2
MCS1 QPSK 1/2 1/2 1/2 1/2
MCS2 QPSK 3/4 3/4 3/4 3/4
MCS3 16-QAM 1/2 1/2 1/2 1/2
MCS4 16-QAM 3/4 3/4 3/4 3/4
MCS5 64-QAM 2/3 2/3 2/3 2/3
MCS6 64-QAM 3/4 3/4 3/4 3/4
MCS7 64-QAM 5/6 5/6 5/6 5/6
VMCS8 256-QAM - - 3/4 3/4
VMCS9 256-QAM - - 5/6 5/6
VMCS10 1024-QAM - - - 3/4
VMC11 1024-QAM - - - 5/6
 
Table 5 Code rate corresponding to 802.11 standard
 
(5) Number of effective sub-carriers
 
The carrier is similar to the symbol in the frequency domain. One sub-carrier carries one symbol, and the number of sub-carriers under different modulation methods and bandwidths is various.
 
  Bandwidth 802.11n 802.11ac 802.11ax
Minimum Carrier Bandwidth - 312.5 KHz 312.5 KHz 78.125KHz
 
Number of valid sub-carriers
 
  HT20 52 52 234
  HT40 108 108 468
  HT80 - 234 980
  HT160 - 2 x 234 2 x 980

Table 6 Number of sub-carriers corresponding to 802.11 standard

At this point, we can calculate the maximum rate of a single spatial stream of 802.11ac and 802.11ax under the HT80 bandwidth:
 
 
PHY 1/(Symbol+GI) Number of bit /Symbol Code rate Effective subcarrier Rate
802.11ac 1/(3.2us+0.4us) 8 5/6 234 433 Mbit/s
802.11ax 1/(12.8us+0.8us) 10 5/6 980 600 Mbit/s

SmileMbb, a subsidiary of V-SOL, has rapidly launched 5G CPE Router XZC5552 product supporting wi-fi6,the device adopts qualcomm QCA6391 Wifi chipset,this chipset supports Wi-fi6 Technology, According to the above calculation method, in 2.4Ghz, we can calculate the maximum rate of two spatial streams of 802.11ax under HT40 bandwidth is 573.5Mbit/s. in 5Ghz, we can calculate the maximum rate of two spatial streams of 802.11ax under HT80 bandwidth is 1201Mbit/s.

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