Hi IEEE 802.11 Key Concepts
Let’s get started with the IEEE 802.11 Journey synopsis. Standards are defined at physical and mac-sub layer(data-link). We are referring to different ways of transmitting data over the air. Also how our communication signal would deliver information. One of the original ones we’ve come across is FHSS (Frequency Hopping Spread Spectrum) and DSSS (Distributed Sequence Spread Spectrum).
In 2007, the IEEE consolidated 8 ratified amendments along with the original standard, creating a single document that was published as the IEEE standard 802.11-2007
The standard covers IEEE standard 802.11-1999, 802.11a.1999, 802.11b-1999, 802.11g-2003,802.11i-2004
802.11b (Sep 1999) is high rate DSSS – Based on 2.4GHz to 2.4835 GHz ISM band
802.11a (Sep 1999) is OFDM (Orthogonal Frequency Divisional Multiplexing) would operate in 5GHz frequency. There are 3 U-NIII (Unlicensed National Information Infrastructure) frequency bands consisting of 12 channels.
802.11b (1999) – High Rate DSSS, operates in 2.4 GHz frequency. OFDM transmission type and supports BPSK (binary phase shift keying) and QPSK (Quadrature PSK) – 1 & 5.5Mbps and 2 & 11 Mbps.
802.11g (June 2003) – Speeds upto 54Mbps/works similar to 802.11b in 2.4 GHz. Used a new technology called Extended Rate Physical (ERP) – ISM frequency band.
802.11i (Security) – From 1997 – 2004, not much defined in terms of security in the original 802.11 standard. Three key components of security solution – Data Privacy/Data Integrity/Authentication. This amendment defined a RSN (Robust Security Network).
802.11r-2008 (FT)- Technology is more often referred to as fast secure roaming because it defines faster handoffs when roaming occurs between cells in WLAN using a strong security defined by RSN.
802.11w (Sep 2009) – IEEE Task Group was a way of delivering management frames in a security manner. Preventing the management frames from being able to be spoofed.802.11 – only on 2.4. Uses hi rate DSSS. It actually came out before 802.11a. Enabled 5.5 and 11Mbps data rates. 22MHz wide channels. Today these rates have become legacy rates.
802.11n (October 2009) – also known as Wi-Fi 4 is an amendment that improves upon the previous 802.11 standards by adding multiple-input multiple-output antennas (MIMO). 802.11n operates on both the 2.4 GHz and the 5 GHz bands. Support for 5 GHz bands is optional. Its net data rate ranges from 54 Mbit/s to 600 Mbit/s
802.11ac (December 2013) – VTH (Very high throughput, wider channel (20MHz-160MHz) – also known as Wi-Fi 5 is an amendment to IEEE 802.11, published in December 2013, that builds on 802.11n. Changes compared to 802.11n include wider channels (80 or 160 MHz versus 40 MHz) in the 5 GHz band, more spatial streams (up to eight versus four), higher-order modulation (up to 256-QAM vs. 64-QAM), and the addition of Multi-user MIMO (MU-MIMO). As of October 2013, high-end implementations support 80 MHz channels, three spatial streams, and 256-QAM, yielding a data rate of up to 433.3 Mbit/s per spatial stream, 1300 Mbit/s total, in 80 MHz channels in the 5 GHz band
802.11ax ( Sometime in 2019*) – IEEE 802.11ax also known as Wi-Fi 6 is the successor to 802.11ac, and will increase the efficiency of WLAN networks. Currently in development, this project has the goal of providing 4x the throughput of 802.11ac at the user layer, having just 37% higher nominal data rates at the PHY layer. More can be read here
While learning about 802.11 PHYs (Physical) I have come across this extremely useful table from cleartosend podcasts/posts as below