What is the IEEE 802 11n

IEEE 802.11n

IEEE 802.11n (n-WLAN, in the preliminary version too Draft-N called) is a standard for wireless networks (WLAN). The first draft draft) of the standard was adopted on January 20, 2006; the final version was ratified by the IEEE on September 12, 2009. Since devices that followed the draft standard came onto the market before ratification, they were designated as Draft-n-compatible.

Since its publication on October 29, 2009, the standard has defined a technique for setting up wireless local networks. The maximum gross data rates should be 600 Mbit / s. Several transmitting and receiving antennas are used for this purpose.

technology

802.11n uses the technology for data transmission Multiple input multiple output (MIMO). Compared to older WLAN technologies, the standard either achieves the same data rates over longer distances or a higher data rate over the same distance. The broadening of the transmission channels from 20 MHz to 40 MHz and the use of four antennas increases the gross data rate to 600 Mbit / s.

802.11n can work in both the 2.4 GHz frequency range and the 5 GHz frequency range.

802.11n achieves per parallel content stream (engl. stream) maximum 150 Mbit / s (gross); For higher data rates, several (up to 4) streams must be bundled. This requires a corresponding number of transmitting and receiving antennas (up to 4) on both sides. Constructions that provide more antennas than there are parallel streams are possible (e.g. two streams - 300 Mbit / s - with three antennas).

In technical terms, the number of transmitter and receiver currents present in a device is represented as a short form with the letters T for transmitter and R for receiver. Then describes z. B. the abbreviation 3T3R three transmit and three receive streams each.[1]

In 802.11n, MIMO modulation uses orthogonal frequency division multiplex modulation as the basic modulation. The individual carriers of this OFDM modulation can be modulated using BPSK, QPSK or QAM, depending on the quality of the connection.

compatibility

802.11n WLANs are compatible with 802.11b and 802.11g networks. The compatibility mode enables the coexistence of 802.11n and existing 802.11a networks. The compatibility mode can also be deactivated in some implementations (so-called “greenfield mode”) in order to increase the performance of the 11n network. However, this lowers the performance of other 802.11a networks active at the same location, since in this case they interpret the 802.11n network as radar beams and change their channel due to the prescribed DFS, which ultimately leads to a total failure due to DoS in the 802.11a network can lead[2]. Since the 802.11n draft still mandated the use of WPA2, WPA2 (AES) must be explicitly selected as encryption for the Draft-N devices in order to be able to use the full bandwidth[3].

State of the development of the standard

The WLAN standard 802.11n was originally supposed to be adopted by the IEEE in mid-2007. In May 2006, however, a final draft was not adopted[4].

Version 7.0 of the draft was approved in November 2008[5] and in March 2009 version 8.0[5]. The final version was officially adopted in September 2009[6] and published on October 29, 2009[7].

Comparison of the IEEE standards

protocolreleasedfrequencyThroughput (net)Data rate (gross)Modulation / multiplex methodRange (indoors, depending on walls)Range (radius outdoors, including a wall)
802.1119972.4 GHz0.9 Mbit / s2 Mbit / sFHSS-GFSK, DSSS-DBPSK / DQPSK≈ 20 meters≈ 100 meters
802.11a19995 GHz23 Mbit / s54 Mbit / sOFDM-BPSK / QPSK / QAM≈ 35 meters≈ 120 meters
802.11b19992.4 GHz4.3 Mbit / s11 Mbit / sDSSS-CCK≈ 38 meters≈ 140 meters
802.11g20032.4 GHz19 Mbit / s54 Mbit / sOFDM-BPSK / QPSK / QAM≈ 38 meters≈ 140 meters
802.11nSeptember 2009 Standard ratified1
released on October 29, 20092
2.4 GHz
5 GHz
240 Mbit / s5600 Mbit / s3MIMO-OFDM-BPSK / QPSK / QAM≈ 70 meters≈ 250 meters
802.11yJune 2008 43.7 GHz23 Mbit / s54 Mbit / s≈ 50 meters≈ 5000 meters

Swell:

Individual evidence

  1. METHOD AND APPARATUS FOR ADAPTIVE REDUCED OVERHEAD TRANSMIT BEAMFORMING FOR WIRELESS COMMUNICATION SYSTEMS. Patent docs. Retrieved February 3, 2011.
  2. ↑ https: //mentor.ieee.org/802.11/file/08/11-08-0351-02-000n-new-evidence-that-11n-greenfield-devices-causes-false-radar-detections-on-dfs -channels.ppt
  3. ↑ http: //www.searchnetworking.de/forum/messages.cfm? Threadid = E3313E1B-2282-490B-B5F0EAECBC208A83
  4. ↑ Jens Ihlenfeld: 802.11n: WLAN standard fails if agreed. In: Golem.de, May 4, 2006. Retrieved February 3, 2011.
  5. abStatus of Project IEEE 802.11n(en). March 2009. Retrieved February 3, 2011.
  6. ↑ Alexandra Kleijn: IEEE ratifies WLAN standard 802.11n. In: heise online, September 12, 2009. Retrieved February 3, 2011.
  7. 802.11n-2009 IEEE Standard for Information technology - Telecommunications and information exchange between systems - Local and metropolitan area networks.October 29, 2009, ISBN 978-0-7381-6047-4, doi: 10.1109 / IEEESTD.2009.5307322 (online, accessed August 25, 2010).

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