f = 1/T
f = 1/T

1.2 Describe IEEE 802.11 standards and protocols



In this chapter I will describe some wireless protocols and standards, but not all of them:

802.11 - I could say the first wireless generation that was published in 1997. It operates in 2.4 GHz band and allows  1 and 2 Mbps.


802.11b - This is the IEEE 802.11b standard ratified in 1999. Operates in 2.4 GHz band and support data rates of: 1 Mbps, 2 Mbps, 5.5 Mbps and 11 Mbps. In many country 3 non-overlapping channels are using (1,6,11) and some case for channels whith low overlaps: (1,5,9,13)


802.11a - IEEE 802.11a standard, operate in the 5 GHz band , and support data rates: 6,9,12,18,24,36,48 and 54 Mbps. Differents modulations are using to provide this differents rate (BPSK, QPSK and QAM).


802.11g: IEEE 802.11g standard, ratified in 2003 and operate in 2.4 GHz frequency band, and is backward compatible with 802.11b standard. It is allow data rates of:

6,9,12,18,24,36,48,54 Mbps and based on OFDM.


802.11n: IEEE 802.11n was ratified in 2009. this standard increases the available speed of 802.11. This is done by using different technologies as:

  •    Channel bonding (combination of 2 channels in 5 GHz band) --> Channel width of 40 MHz
  • Spatial stream multiplexing, based in MIMO technology, using of multiple antennaes (Tx and Rx)
  • Transmitting Beamforming: The use of more than one transmitter at the sending station to improve the signal at the receiving station.

802.11n operation in two wireless band: 2.4 GHz and 5 GHz. It is backwale compatible with 802.11g and 802.11g. It is not compatible with 802.11b.


802.11ac: IEEE 802.11ac standard ratified in 2013. It is operates exclusively in 5 GHz band. It increase the channel width to 80 and 160 MHz.


Another amendement are in studing as: 802.11ax


802.11d: Published in 2001, allow AP and client device to exchange information about country of operation.


802.11h: Published in 2003, describe how operations in 5 GHz avoid collision in DFS environment (as Airport radar). This concern UNII-2 and UNII-2e in 5GHz band.


802.11e: This amendment was published in 2005, it include provisions for QoS (Quality of Service over Wi-Fi.


802.11k: Published in 2008, describes functions for RRM (Radio Ressource Management). Allow the AP to send to the client the list of neighboring APs that  to the client to could roam to.


802.11r:  Published in 2008, 802.11r also called FT (Fast Transition) this decribes provisions for fast  key exchange during the roaming.


802.11w: Published in 2010, this concern the Protection of  Management Frame (PMF)


802.11v: Published in 2011, this concern the BSS transition. It decribes how an AP and client can exchange information on the next best AP for the client.