What is IEEE 802.11az | Advantages of 802.11az WiFi Standard
This page covers IEEE WiFi 802.11az standard features. It mentions benefits or advantages of 802.11az WiFi used as micro-location positioning.
What is IEEE 802.11az WiFi ?
Bluetooth 5.1, UWB (Ultra Wide Band ) and 802.11az technologies are used for micro-location positioning. There are various uses of these micro-location technologies. The applications include finding things at homes and warehouses, detecting cars and their parts, auto following drones, prevention of accidents etc.
The IEEE 802.11az wifi standard defines ToA (Time of Arrival) based position estimation algorithm for WiFi clients (i.e. STATIONS) in multi-path environment. This standard helps Station (STA) to identify its position in a wifi network with respect to multiple APs (Access Points) or Routers.
This 802.11az amendment defines modifications to PHY layer and MAC layer. In comparison to previous IEEE standard i.e. 802.11-2016, 11az enables absolute as well as relative position estimation with high accuracy. It is known as next generation positioning (NGP) standard which is planned to be finalized by 2022. Unlike RSSI based positioning, this NGP standard uses Fine Timing Measurement (FTM) method to determing position of WiFi STA.
The figure depicts ToF (Time of Flight) measurement and range calculation.
➨ToF = [ (t4-t1) - (t3-t2)]/2
➨Range = Speed of light x ToF
Following are the features of 802.11az micro-location technology.
• Defines two PPDU formats viz. HE ranging NDP & HE trigger based ranging NDP (Null Data Packet).
• Uses multiple repetitions of HE-LTF symbols in single user waveform and multi user waveform.
• Employs FTM which uses RTT (Round Trip Time) information to estimate distance between Wi-Fi enabled STAs (i.e. clients or stations) and WiFi APs (access points). RTT uses ToD (Time of Departure) and ToA (Time of Arrival) timestamps.
• It utilizes wide bandwidth channels (up to 160 MHz in WiFi 6 version and up to 320 MHz in WiFi 7 version) for providing improvement on accuracy in positioning.
• It utilizes multi-user capabilities as defined in WiFi 6 version.
• APs use OFDMA in the uplink and downlink and trigger based ranging to get ranging information from multiple STAs in single transmit opportunity.
Benefits or advantages of 802.11az
Following are the benefits or advantages of 802.11az technology :
➨It improves location and positioning of the wifi users. Hence WiFi router quickly tracks precise location of WiFi clients accurately.
➨This standard increases energy efficiency of the wifi network.
➨It reduces wireless medium utilization.
➨It is scalable to dense deployment environments.
➨It incorporates security features.
➨It offers higher resolution due to use of wider bandwidth channels.
➨It uses MIMO to provide better resilience to multi-path effects.
➨Trigger based ranging reduces overhead to significant extent and improves scalability to more STAs (i.e. stations).
Out of three technologies, UWB provides highest accuracy with centimeter level positioning. Bluetooth 5.1 offers sub-meter level accuracy and 802.11az based WiFi offers decimeter level accuracy.
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