What is IEEE 802.11n? - Explained


IEEE 802.11n-2009 is also known as IEEE 802.11n. IEEE 802.11n is the wireless networking standard which is released by the IEEE after the IEEE 802.11g standard.

1. Technology

IEEE 802.11n is a breakthrough in the wireless short distance networking interfaces at the time. The technology which was used in the 802.11g and 802.11b is different from the 802.11n wireless technology.

Unlike the 802.11b or 802.11g and 802.11a, 802.11n can use both bands 2.4GHz and 5GHz to transfer data and operate the at the optimal efficiency.

1.1 MIMO

802.11n uses MIMO technology which is multiple input and multiple output by using multiple antennas rather using a single antenna. The data transfer rate which was possible to transfer in the 802.11g and 802.11b wireless networks 54Mbit/s got massively higher in the 802.11n wireless network up to a theoretical speed of 600Mbit/s with the use of four spatial streams at a channel width of 40MHz to the PHY or physical layer.

With the MIMO technology the 802.11n started supporting frame aggregation to the MAC layer, security improvements into the wireless network.

MIMO technology uses SDM also known as Spatial Division Multiplexing which spatially multiplexes multiple independent data streams transferred simultaneously within one spectral channel of bandwidth. Each spatial stream requires a discrete antenna at both the transmitter and the receiver by using separate radio frequency chains by converting each and every signal analog to digital in each antenna.

1.2 Data Encoding 

Transmitter and the receiver in the access point or the router of the 802.11n enabled device uses precoding and postcoding techniques to achieve the capacity required in MIMO link and to gain the maximum out of the multi antenna technology implemented in MIMO.

In addition Spatial beamforming and spatial coding improves the signal quality at the decoding stage of the device and increase data throughput via spatial multiplexing and increase range by exploiting the spatial diversity by the techniques like Alamouti coding.


2. Modulation Types

Since there are multiple bands are used in the 802.11n, it requires multiple modulation and coding schemes to achieve the efficiency that promised by the specification.


MSC Index
Spatial Streams
Coding Rate
Data Rate in Mbit/s
20MHz Channel40 MHz Channel
800ns GI400ns GI800ns GI400ns GI
01BPSK1/26.57.213.515
11QPSK1/21314.42730
21QPSK3/419.521.740.545
3116-QAM1/22628.95460
4116-QAM3/43943.38190
5164-QAM2/35257.8108120
6164-QAM3/458.565121.5135
7164-QAM5/66572.2135150
82BPSK1/21314.42730
92QPSK1/22628.95460
102QPSK3/43943.38190
11216-QAM1/25257.8108120
12216-QAM3/47886.7162180
13264-QAM2/3104115.6216240
14264-QAM3/4117130243270
15264-QAM5/6130144.4270300
163BPSK1/219.521.740.545
173QPSK1/23943.38190
183QPSK3/458.565121.5135
19316-QAM1/27886.7162180
20316-QAM3/4117130243270
21364-QAM2/3156173.3324360
22364-QAM3/4175.5195364.5405
23364-QAM5/6195216.7405450
244BPSK1/22628.85460
254QPSK1/25257.6108120
264QPSK3/47886.8162180
27416-QAM1/2104115.6216240
28416-QAM3/4156173.2324360
29464-QAM2/3208231.2432480
30464-QAM3/4234260486540
31464-QAM5/6260288.8540600
324BPSK1/4N/AN/A66.7
33-382Asymmetric Mod.DependsDependsDependsDepends
39-523Asymmetric Mod.DependsDependsDependsDepends
53-764Asymmetric Mod.DependsDependsDependsDepends
77-127ReservedN/AN/AN/AN/A


Frame Aggregation


Frame aggregation is a process of packing multiple MSDUs or MPDUs together to reduce the overheads and the over multiple frames. There are two types of frame aggregations used in the 802.11n wireless network.

1. Aggregation of MAC Service Data Units also known as MSDUs is at the top of the MAC or media access control.
2. MPDUs is known as Aggregation of MAC protocol data units at the bottom of the MAC or the Media Access Control.

By using frame aggregation can improve the performance of the network and it's efficiency to achieve high speed data transfer rates.