User's Guide

Table Of Contents
hwc_apstartup.fm
Configuring the Wireless AP
Wireless AP overview
9034530-02,
March 2010
HiPath Wireless Controller, Access Points and Convergence Software V7.11, User Guide 91
To configure the HiPath Wireless 802.11n AP to achieve this high link rate, see
Section 4.4.5.2, “Achieving high throughput with the Wireless 802.11n AP”, on
page 150.
Note: The Wireless 802.11n AP is backward-compatible with existing
802.11a/b/g networks.
Note: The Wireless 802.11n AP cannot operate as a stand-alone access point.
MIMO
The mainstay of 802.11 AP is MIMO (multiple input, multiple output) — a
technology that uses advanced signal processing with multiple antennas to
improve the throughput. MIMO takes advantage of multipath propagation to
decrease packet retries to improve the fidelity of the wireless network.
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 en route to the 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 throughput.