I’ll be writing these notes as time will pass. They are firstly intended to be an online study reference for myself and everybody else who is interested in Wi-Fi. My first post will be an introduction to all the 802.11 standards.
802.11 Original standard
The original standard dates back to the year 1997 and is also known as IEEE 802.11-1997
It had 3 physical layer specifications :
- FHSS (Frequency Hopping Spread Spectrum)
- DSSS (Direct Sequence Spread Spectrum)
Operating band = 2.4Ghz to 2.4835 Ghz
Most devices in that era used FHSS but some also used DSSS.
Data Rates = 1 and 2 Mbps
The 802.11b standard dates back to the year 1999 and is also known as IEEE 802.11b-1999
It had 1 physical layer specification :
- DSSS (Direct Sequence Spread Spectrum)
Operating band = 2.4 Ghz to 2.4835 Ghz
Most devices that where 802.11b where not backward compatible with the legacy 802.11 (FHSS). However the standard was backwards compatible with the DSSS 1 and 2Mbps rates.
The higher data rates where accomplished due to using a new spreading/coding technique called CCK (Complementary Code Keying) and a spreading technology called the Barker Code.
Data Rates = 1, 2, 5.5 and 11 Mbps
One thing to remember is that the higher data rates (5.5 and 11 Mbps) are known as HR-DSSS.
The 802.11a standard dates back to the year 1999 and is also known as IEEE 802.11a-1999
It has 1 physical layer specification :
- OFDM (Orthogonal Frequency Division Multiplexing)
Operating band = 5 Ghz (UNII-1, UNII-2 and UNII-3 (Unlicensed National Information Infrastructure))
Total of 12 channels!
Data Rates = 6, 9, 12, 18, 24, 36, 48 and 54Mbps
As 802.11a works in a different operating band than 802.11 and 802.11b backward compatibility is not possible.
The 802.11g standard dates back to the year 2003 and is also known as IEEE 802.11g-2003
It has 2 mandatory physical layer specification and 2 optional:
- ERP-OFDM (Extended Rate Physical Orthogonal Frequency Division Multiplexing)
- ERP-DSSS/CCK (Extended Rate Physical Direct Sequence Spread Spectrum)
- ERP-DSSS/PBCC (Packet Binary Convolutional Coding) <— Beyond the scope of the CWNA exam
- DSSS-OFDM (l Direct Sequence Spread Spectrum -Orthogonal Frequency Division Multiplexing )<— Beyond the scope of the CWNA exam
Operating band = 2.4 Ghz to 2.4835 Ghz
|ERP-OFDM||Mandatory||6, 9, 12, 18, 24, 36, 48, 54|
|ERP-DSSS||Mandatory||1, 2, 5.5, 11|
|ERP-DSSS/PBCC||Optional||1, 2, 5.5, 11, 22, 33|
|DSSS-OFDM||Optional||6, 9, 12, 18, 24, 36, 48, 54|
ERP-OFDM was created to provide the higher data-rates of 802.11a in the 2.4Ghz band.
ERP-DSSS was created to remain backwards compatible with 802.11 (DSSS) and 802.11b (HR-DSSS) radios.
The 802.11d standard dates back to the year 2001 and is also known as IEEE 802.11d-2001
This standard was created to be compliant with regulatory domains of differente regions. Regulations in the US are not the same as they are in for ex Europe.
This amendment adds specific region information in Wi-Fi beacons. (eg : Country code, frequency, power)
The 802.11h standard dates back to the year 2003 and is also known as IEEE 802.11h-2003
The 802.11h standard provides mechanisms for DTS (dynamic frequency selection) and TPC (transmit power control) and added the UNII-2 Extended band.
DTS and TPC where created to avoid interfering with Radar systems.
Operating band = 5 Ghz
|UNII1 (lower) 5150 GHz- 5250 GHz||802.11a||4|
|UNII2 (middle) 5250 GHz- 5350 GHz||802.11a||4|
|UNII2 Extended 5470 GHz- 5725 GHz||802.11h||11|
|UNII3 (upper) 5725 GHz- 5825 GHz||802.11a||11|
The 802.11i standard dates back to the year 2004 and is also known as IEEE 802.11i-2004
The basic security exist of 3 components.
- Data privacy (encryption)
- Data integrity (protection from modification)
- Authentication (identity verification)
The 802.11 original standard only had 64 bit static encryption called WEP (wireless equivalent privacy). WEP encryption was early on compromised and there was a need for better security. The 802.11i standard added a RSN (robust security network) by adding better encryption and better authentication methods.
- Data privacy
802.11i added a new encryption method called CCMP (Counter Mode with Cipher Block Chaining Message Authentication Code Protocol) which uses the AES (Advanced Encryption Standard) algorithm. However the 802.11i also defines the optional TKIP (Temporal Key Integrity Protocol) which uses RC-4 but this is far less used.
- Data Integrity
WEP uses the data integrity method named ICV (Initialization Check Value). TKIP uses MIC (Message Integrity Check). The new CCMP protocol uses a much stronger MIC and a 32-bit CRC known as FCS (frame check sequence).
802.11i adds 2 methods of security. The first one is 802.1X and the other one is PSK (preshared keys)
One thing extra to know is that the Wi-Fi alliance created a certification called WPA2 (Wi-Fi protected Access 2) which includes all above security amendments. WPA1 was a preliminary release which did not include all above security enhancements.
The 802.11j standard dates back to the year 2004 and is also known as IEEE 802.11j-2004
This standard was created to comply with Japanese regulations. This was accomplished by adding the Japanese 4.9 Ghz and 5.0 Ghz band. Next to the standard 20Mhz OFDM channels, Japan also 10Mhz channels.
Operating band = 4.9 Ghz to 5.091 Ghz
10Mhz data rates = 3, 4, 5, 6, 9, 12, 18, 24 and 27 Mbps.
The 802.11e standard dates back to the year 2005 and is also known as IEEE 802.11e-2005
This standard came as an answer to the QOS (quality of service) problems that arose with VoWifi (Voice over Wifi). Next to the existing DCF (Distributed Coordination Funtion) and the PCF (Point coordination Function), 802.11e adds HCF (Hybrid Coordination Function).
HCF has 2 access mechanisms
- EDCA (Enhanced Distributed Channel Access) which is an extension to DCF.
- HCCF (Hybrid Coordination Function Controlled Channel Access) is an extension of PCF. <– Both have never really been adopted by WLAN vendors
The Wi-Fi Alliance created a certification called WMM (Wi-Fi multimedia) which included above 802.11e standard.
The 802.11 version 2012 is also known as IEEE 802 view website.11-2012
In 2012 the IEEE created a standard called 802.11-2012 which included the following amendments.
I’ll go into detail to each of the above 802.11-2012 ratified amendments
The 802.11r standard dates back to the year 2008 and is also known as IEEE 802.11r-2008
Another change needed to get VoWiFi working properly was a fast way to roam. The well known name for 802.11r is FT (bast basic service set transition) or Fast secure roam. 802.11r makes it possible for a client to setup a QOS stream and setup a new security association with another AP allowing bypassing the full 802.1X authentication.
The 802.11k standard dates back to the year 2008 and is also known as IEEE 802.11k-2008
802.11k provides RRM( radio resource measurements), this is done gathering information from the AP or WLAN controller for the PHY and the MAC layer. Following are some of these measurements
- TPC (transmit power control) We have seen this before in the 802.11h amendment. In 802.11k we use this information for all Frequency bands and not only in the 5Ghz as previously described for 802.11h
- Client statistics (SNR, Signal strength, data rates, frame stransmissions, retries and errors are all client statistics that are being gathered by the AP or Wlan controller)
- Channel statistics (channel-load and noise-floor information is sent from the client to the AP or Wlan Controller)
- Neighbor reports (clients learn from the AP or Wlan Controller to which AP they can easily roam)
The 802.11y standard dates back to the year 2008 and is also known as IEEE 802.11y-2008
802.11y is a standard that allows Wi-Fi on different frequencies (eg 3.5Ghz, etc..) Instead of using the default CSMA/CD, 802.11y defines the DSE (dynamic STA enablement) procedures.
The 802.11w standard dates back to the year 2009 and is also known as IEEE 802.11w-2009
This amendment provides a protection to DOS attacks comprised of management frames. Management frame protection is achieved by using CCMP. Broadcast and multicast frames are protected by BIP (Broadcast/Multicast Integrity Protocol).
The 802.11n standard dates back to the year 2009 and is also known as IEEE 802.11n-2009
The 802.11n standard increased the data rates up to 600 Mbps by using a new standard named HT-OFDM
It hasone physical layer specification:
- HT-OFDM (High Throughput Orthogonal Frequency Division Multiplexing)
Operating bands = 2.4 Ghz and 5Ghz
Another big change compared to previous standards is the channel width. 802.11n makes it possible to use 40Mhz wide channels.
Last but not least 802.11n has MIMO (multiple-input, multiple-output)
The 802.11p standard dates back to the year 2010 and is also known as IEEE 802.11p-2010
This standard is known best as WAVE (Wireless Access in Vehicular Environments) it allows for wireless transmissions on speeds up to 200km/h on distances to 1000m (5.850 Ghz to 5.925Ghz in North America). The standard is developed for vehicle to vehicle or vehicle to infrastructure communication.
The 802.11z standard dates back to the year 2010 and is also known as IEEE 802.11z-2010
This standard defines the DLS (direct link setup) operations. DLS allows client devices to bypass the AP and communicate with direct frame exchanges. Most suppliers have yet to incorporate this standard in their devices.
The 802.11u standard dates back to the year 2011 and is also known as IEEE 802.11u-2011
802.11u is known best as WIEN (Wireless Interworking with External Networks). Network discovery and selection by clients, information transfer from external networks with QOS and emergency services provisioning are described in this standard. 802.11u is the basis whereupon the Wi-Fi alliance HOTSPOT 2.0 (passpoint certification) is built. (seamless roaming between cellular networks and Wi-Fi)
The 802.11v standard dates back to the year 2011 and is also known as IEEE 802.11v-2011
This standard is best known as the WNM (Wireless Network Management). AP and stations can use 802.11v to exchange network status so that every wireless device on the network is aware of the state and topology of the network. WNM protocols can exchange location, provide BSSID capabilities and offer a WNM-sleep mode. The Wi-Fi alliance has taken some of these to include in their Voice-Enterprise certification.
The 802.11s standard dates back to the year 2011 and is also known as IEEE 802.11s-2011
802.11s standardizes interoperability for MESH networks. APs can act as wireless gateways towards another wireless system. WDS (wireless distribution system). The routing protocol used to handle these mesh networks is called HWMP (Hybrid Wireless Mesh Protocol)
POST 2012 AMENDMENTS
The 802.11ae standard dates back to the year 2012 and is also known as IEEE 802.11ae-2012
This amendment specifies extra QOS Management enhancements. Most specific a QMF (Quality-of-service management frame).
The 802.11aa standard dates back to the year 2012 and is also known as IEEE 802.11aa-2012
This amendment specifies extra QOS MAC enhancements. It provides better management, link reliability and better application performance. It uses a GCR (groupcast with retries).
The 802.11ad standard dates back to the year 2012 and is also known as IEEE 802.11ad-2012
The 802.11ad amendment works in the 60Ghz band and enables VHT (Very High Throughput) data rates (up to 7Gbps) over short distances. Some uses for this amendment will be Wireless Docking, streaming, etc. The VHT requires a new encryption mechanism called GCMP (Galois/Counter Mode Protocol).
The 802.11ac standard dates back to the year 2013 and is also known as IEEE 802.11ac-2013
The 802.11ac standard defines VHT in the frequencies below 6Ghz. By default 802.11ac will only be used in the 5Ghz band. Extra features include.
- Wider channels (80Mhz and 160Mhz channels are described in the amendment however due to the limited number of channels available in the 5Ghz 160Mhz channels will not be see much in live networks.)
- 256-QAm modulation
- Up to 8 spatial streams.
- MU-MIMO (multi-user mimo)
The 802.11af standard dates back to the year 2014 and is also known as IEEE 802.11af-2014
802.11af describes the use of Wi-Fi in the new unlicensed spectrum of TV. (it’s called White-Fi) The frequencies where 802.11af will in operate are between 54Mhz and 790Mhz. Due to the lower frequencies, data-rates will be low. (between 26.7 Mbps and 35.6 Mbps). Channel widths will be between 6Mhz and 8Mhz. If you bundle channels and spatial streams (up to 4) max data-rate between 426 Mbps and 568 Mbps.
One thing to mention is that 802.22-2011 also references wireless communication in the TV spectrum.
802.11 DRAFT AMENDMENTS
The 802.11ah is a draft amendment.
802.11ah describes the use of Wi-Fi in the frequencies below 1Ghz. The main use will be M2M (machine 2 machine) communication over long distance. IoT (Internet of Things) for example.
The 802.11ai is a draft amendment.
802.11ai will provide a FILS (fast initial link setup). The goal is to setup a secure connection in less than 100msec.
The 802.11aj is a draft amendment.
802.11aj proposes to make changes to the MAC and PH layer to allow operation in the CMMW (Chinese Millimeter Wave) band.
The 802.11aq is a draft amendment.
802.11aq will enable information delivery (ad’s) to stations before they are associated to the network.
- What does Wi-Fi really mean?
- CWNA notes part 2 : Memorizing MCS rates