IEEE 802.11n-2009

IEEE 802.11n ( n Wi-Fi, in the preliminary version also called Draft- N) is a standard for wireless networks ( WLAN). The standard defines a technique for the construction of wireless local area networks. The theoretically achievable gross data rate is 600 Mbit / s Standard compliant devices that came to market before the publication of the standards in October 2009, called Draft-N compatible.

Technology

802.11n uses for data transmission the art Multiple Input Multiple Output (MIMO). Compared with older wireless standard techniques of either the same data rates over longer distances or at the same distance achieves a higher data rate. The widening of the transmission channels of 20 MHz to 40 MHz and the use of four antennas increases the gross data rate of 600 Mbit / s

802.11n can operate in the 2.4 GHz frequency range and also operate in the 5 GHz frequency range.

802.11n achieved per current content stream (English stream) up to 150 Mbit / s ( gross); for higher data rates need two to max. four streams are bundled. At least one transmitting and one receiving antenna is necessary to separate the streams again can per stream. To improve the transmission characteristics as well as more antennas are used as flows, are frequently encountered, for example, three antennas for two streams (300 Mbit / s).

As a summary of the number of existing in a device transmitter and receiver streams with the letter T for transmitter (English for transmitter) and receiver R is represented (English for receiver) in the jargon. Then, for example, the abbreviation 3T3R describes three transmission and reception streams.

MIMO modulation is used for 802.11n an orthogonal frequency division multiplex modulation as the base modulation. The individual carriers of the OFDM modulation can be modulated by means of 2 -PSK, 4 -PSK, 16 -QAM or 64- QAM depending on the quality of the connection.

Compatibility

WLAN 802.11n is compatible with 802.11b and 802.11g networks. Compatibility mode allows a coexistence of 802.11n and 802.11a existing networks. The compatibility mode can also be activated in some implementations (so-called "Green Field Mode" ) to increase the performance of the 11n network. However, this reduces the performance of other active at the same place 802.11a networks, since they interpret the 802.11n network in this case as radar beams and change their channel due to the prescribed DFS, which ultimately leads to a complete failure by DoS on the 802.11a network can result. Since the 802.11n draft still mandatory that you use WPA2 foresaw, must be selected as the encryption at the Draft- N devices explicitly WPA2 ( AES) in order to utilize the full bandwidth.

State of development of standards

The first draft (English draft) of the standard was adopted on 20 January 2006, the final version was September 12, 2009 ratified by the IEEE. The 802.11n wireless standard should be adopted by the IEEE originally mid-2007. In May 2006, a final draft was not adopted.

In November 2008, the draft was adopted in version 7.0 and version 8.0 in March 2009. In September 2009, the final version was officially adopted and published on October 29, 2009.

Comparison of IEEE standards

Sources:

IEEE 802.11a | 802.11b | 802.11g | IEEE 802.11n | IEEE 802.11p

Additional extensions: IEEE 802.11c | IEEE 802.11d | IEEE 802.11e | 802.11f IEEE | IEEE 802.11h | IEEE 802.11i | IEEE 802.11j | IEEE 802.11s