AM18x Wireless Connectivity 802 11n Parameters

=Introduction= As part of the 802.11n standard, there are Information Elements (IE's), which are proprietary for the standard. These information elements define the capabilities of the 802.11n communication. There are three 802.11n operating modes: HT, Non-HT, and HT Mixed.

High Throughput (Greenfield) Mode
An 802.11n AP using High Throughput (HT) mode – also known as Greenfield mode – assumes that there are no nearby legacy stations using the same frequency band. If legacy stations do exist, they cannot communicate with the 802.11n AP. HT mode is optional.

Non-HT (Legacy) Mode
An 802.11n AP using Non-HT mode sends all frames in the old 802.11a/g format so that legacy stations can understand them. That AP must use 20 MHz channels and none of the new HT features described in this paper. All products must support this mode to ensure backward compatibility, but an 802.11n AP using Non-HT delivers no better performance than 802.11a/g.

HT Mixed Mode
The mandatory HT Mixed mode will be the most common 802.11n AP operating mode for the next year or so. In this mode, HT enhancements can be used simultaneously with HT Protection mechanisms that permit communication with legacy stations. HT Mixed mode provides backwards compatibility, but 802.11n devices pay significant throughput penalties as compared to Greenfield mode.   In the first figure above we can see the following:   In the second figure above we can see the following:  <BR><BR> In the third figure above we can see the following:<BR/>
 * The AP can operate in both 20MHz and 40MHz (mixed mode)
 * The Module Coding Schemes (MCS's) supported are MCS 0 to MCS 15
 * Maximum MSDU is 7935 bytes (maximum length of grouped packets into one MAC frame)
 * The AP supports only 1 spatial stream
 * Dual Beacon is not supported
 * Dual CTS is not supported