User's Manual

Configuring the Wireless AP
hwc_apstartup.fm
Wireless AP overview
A31003-W1050-U100-2-7619
, March 2008
62 HiPath Wireless Controller, Access Points and Convergence Software V5 R1 , C20/C2400 User Guide
The 802.11n AP’s MIMO radio sends out one or two radio signals through its three
antennas. Each of these signals is called a spatial stream. Because the location
of the antennas on the 802.11n AP is spaced out, each spatial stream follows a
slightly different path to the client device. Furthermore, the three spatial streams
get multiplied into several streams as they bounce off the obstructions in the
vicinity. This phenomenon is called multipath. Since these streams are bounced
from different surfaces, they follow different paths to the client device. The client
device, which is also 802.11n compliant, also has multiple antennas. Each of the
antennas independently decodes the arriving signal. Then each antenna’s
decoded signal is combined with the decoded signals from the other antennas.
The software algorithm uses the redundancy to extract one or two spatial streams
and enhances the streams' "signal to noise ratio".
The client device too sends out one or two spatial streams through its multiple
antennas. These spatial streams get multiplied into several steams as they
bounce off the obstructions in the vicinity enroute to 802.11n AP. The 802.11n
AP's MIMO receiver receives these multiple streams with three antennas. Each
of the three antennas independently decodes the arriving signal. Then each
antennas's decoded signal is combined with the decoded signals from the other
antennas. The 802.11n AP's MIMO receiver again uses the redundancy to extract
one or two spatial streams and enhances the streams' "signal to noise ratio".
By using the multiple streams, MIMO doubles the thoroughput.
Figure 5 MIMO in HiPath Wireless 802.11n AP