SMC Networks WBR14S-N3 - annexe 1 Manual page 55

HT Physical Mode Settings
• HT Operation Mode – Packets from 802.11n clients are referred to as High
Throughput (HT) Greenfield packets, in other words packets that can be
transmitted at rates of up to 300 Mbps assuming that HT Channel Bandwidth is set
to 20/40Mhz, see HT Channel Bandwidth next page.
Note: Some 802.11n wireless clients may be capable of transmission rates of up to
600 Mbps, however the wireless AP/Router will only be able to connect to them at
a maximum transmission rate of 300 Mbps.
802.11b/g packets are referred to as non-HT packets, being transmitted at lower
throughput rates. HT mixed format frames contain a preamble compatible with the
non-HT receivers. HT Greenfield frames do not contain a non-HT compatible part.
Support for HT Greenfield format is optional. An HT station that does not support
the reception of an HT Greenfield format frame must be able to detect that an HT
Greenfield format frame is an HT transmission (as opposed to a non-HT
transmission). In this case the receiver must decode the high throughput signal
(HT-SIG) in the packet header and determine if the HT-SIG cyclic redundancy
check (CRC) passes. (Default: Mixed)
• HT Channel Bandwidth – The wireless AP/Router provides a channel bandwidth
of 40 MHz by default giving an 802.11g connection speed of 108 Mbps (sometimes
referred to as Turbo Mode) and a 802.11n connection speed of up to 300 Mbps.
Setting the HT Channel Bandwidth to 20 MHz slows connection speed for 802.11g
and 802.11n to 54 Mbps and 74 Mbps respectively and ensures backward
compliance for slower 802.11b devices. (Default: 20/40MHz)
• Guard Interval – The guard interval between symbols helps receivers overcome
the effects of multipath delays. When you add a guard time, the back portion of
useful signal time is copied and appended to the front. (Default: Auto)
Figure 5-17. HT Physical Mode Settings
5
Wireless Settings
5-21