H3C Technologies H3C WX3000E Series Wireless Switches - Manual (Page 245)

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Figure 218 Remote MAC authentication
When a RADIUS server is used for MAC authentication, you can specify a domain for each wireless
service, and thus send MAC authentication information of different SSIDs to different remote RADIUS
servers.
802.11n
As the next generation wireless LAN technology, 802.11n supports both 2.4GHz and 5GHz bands. It
provides higher throughput to customers by using the following methods:
1. Increasing bandwidth: 802.11n can bond two adjacent 20-MHz channels together to form a
40-MHz channel. During data forwarding, the two 20-MHz channels can work separately with
one acting as the primary channel and the other acting as the secondary channel or work together
as a 40-MHz channel. This provides a simple way of doubling the data rate.
2. Improving channel utilization through the following ways:
802.11n introduces the A-MPDU frame format. By using only one PHY header, each A-MPDU
can accommodate multiple Message Protocol Data Units (MPDUs) which have their PHY
headers removed. This reduces the overhead in transmission and the number of ACK frames to
be used, and thus improves network throughput.
Similar with MPDU aggregation, multiple MAC Service Data Units (MSDU) can be aggregated
into a single A-MSDU. This reduces the MAC header overhead and thus improves MAC layer
forwarding efficiency.
To improve physical layer performance, 802.11n introduces the short GI function, which
shortens the GI interval of 800 us in 802.11a/g to 400 us. This can increase the data rate by
10 percent.