8.2 IEEE 802.11n
In July 2003, the 802.11n task group was formed to create a new wireless LAN standard.
The main goal of this new standard is to give a throughput of at least 100 Mbps at the
MAC data service access point [6]. A number of proposals were made that all share three
common elements: the use of MIMO-OFDM, 20 and 40 MHz channels, and packet
aggregation techniques. Based on this common ground, in July 2005 a joint proposal group
was formed to create the first draft 802.11n standard [5].
The 802.11n standard defines a range of mandatory and optional data rates in both 20
and 40 MHz channels. Table 8.1 lists the Modulation and Coding Schemes (MCS) and
their corresponding data rates for the cases of 1 and 2 spatial streams. For every MCS, 4
data rates are shown, as every MCS can be used in either a 20 MHz channel or a 40 MHz
The 802.11n MIMO-OFDM Standard 181
channel, using either a normal 800 ns guard interval or an optional 400 ns short Guard
Interval. The use of 2 spatial streams with a short guard interval in a 40 MHz channel gives
a highest possible data rate of 300 Mbps. Even higher data rates are possible by using the
optional MCS listed in Table 8.
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