Wi-Fi: 802.11 Physical Layer Explained

Find out more about the 802.11 Wi-Fi Physical Layer

This helpful poster created by Tektronix (R) explains key parameters in the WiFi Physical layer, including 802.11b, 802.11a, 802.11g, 802.11n, 802.11ac.

CableFree WiFi Physical Layer explained: find out about Wi-Fi!
WiFi Physical Layer Explained

A download link to the document in PDF format is here:

What Wi-Fi Parameters do we have to consider?

When building a Wireless Network Key parameters include:

  • Channel Allocation
  • Spectral Shape and Mask
  • Packet Information
  • Data rates
  • Modulation types
  • Transmitter Measurements
  • Channel and Centre Frequency

What is Wi-Fi 6? Wi-Fi 5? Wi-Fi 4?

Under its naming convention, the WiFi alliance calls 802.11ax Wi-Fi 6. 802.11ac is now WiFi 5, and 802.11n is WiFi 4. The idea, according to the WiFi Alliance, is to make matching endpoint and router capabilities a simpler matter for the rank-and-file user of WiFi technology.

Meanwhile it’s important to know that the Wi-Fi Alliance has not made up simpler names for all the 802.11 standards, so it’s important to be familiar with the traditional designations. Also, the IEEE, which continues to work on newer versions of 802.11, has not adopted these new names, so trying to track down details about them using the new names will make the task more complicated.


Released in September 1999, it’s most likely that your first home router was 802.11b, which operates in the 2.4GHz frequency and provides a data rate up to 11 Mbps. Interestingly, 802.11a products hit the market before 802.11a, which was approved at the same time but didn’t hit the market until later.


The first following the June 1997 approval of the 802.11 standard, this standard provided operation in the 5GHz frequency, with data rates up to 54Mbps. Counterintuitively, 802.11a came out later than 802.11b, causing some confusion in the marketplace because customers expected that the standard with the “b” at the end would be backward compatible with the one with the “a” at the end.


Approved in June 2003, 802.11g is the successor to 802.11b, able to achieve up to 54Mbps rates in the 2.4GHz band, matching 802.11a speed but within the lower frequency range.

802.11n (WiFi 4)

The first WiFi standard to specify MIMO, 802.11n was approved in October 2009 and allows for usage in two frequencies – 2.4GHz and 5GHz, with speeds up to 600Mbps. When you hear the term “dual-band”, it refers to being able to deliver data across these two frequencies.

802.11ac (WiFi 5)

802.1ac-compliant devices operate in the 5 GHz frequency space. With Multiple Input, Multiple Output (MIMO) – multiple antennas on sending and receiving devices to reduce error and boost speed – this standard supports data rates up to 3.46Gbps. Some router vendors include technologies that support the 2.4GHz frequency via 802.11n, providing support for older client devices that may have 802.11b/g/n radios, but also providing additional bandwidth for improved data rates.

802.11ax (Wi-Fi 6)

Also called High Efficiency WLAN, 802.11ax aims to improve the performance in WLAN deployments in dense scenarios, such as sports stadiums and airports, while still operating in the 2.4GHz and 5GHz spectrum. The group is targeting at least a 4X improvement in throughput compared to 802.11n and 802.11ac., through more efficient spectrum utilization.

For Further Information

Please Contact Us