H3C Technologies H3C WX3000E Series Wireless Switches - Manual (Page 581)

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Wireless location can be applied to medical monitoring, asset management, and logistics, helping users
effectively manage and monitor assets.
Architecture of the wireless location system
A wireless location system is composed of three parts: devices or sources to be located, location
information receivers and location systems.
• Devices or sources to be located, which can be Tags (small, portable RFIDs, which are usually
placed or glued to the assets to be located) of Aero Scout or Mobile Units (MU). The MUs are
wireless terminals or devices running 802.11. The tags and MUs can send wireless messages
periodically.
• Location information receivers, for example, 802.11 APs, and AeroScout Exciters that are standard
compliant Tags to send wireless messages but do not collect location information.
• Location systems, including location server, AE calculation software, and different types of graphics
software.
Wireless locating process
A wireless location system can locate wireless clients, APs, rogue APs, rogue clients, Tags and other
devices supporting WLAN protocols. Except Tags, all wireless devices will be identified as MUs by the
wireless location system.
1. Send Tag and MU messages
A Tag message is a message sent by an RFID. A Tag message contains the channel number so that
an AP can filter Tag messages whose channel numbers are not consistent with the AP's operating
channel. To make sure more Tags can be detected by the AP, a Tag sends messages on different
channels. A Tag periodically sends messages on one or multiple pre-configured channels, and
then sends location messages on channels 1, 6, and 11 in turn periodically.
MU messages are sent by standard wireless devices. An MU message does not contain the
channel number, so an AP cannot filter MU messages whose channel numbers are not consistent
with the AP's operating channel or illegal packets, which is done by the location server according
to a certain algorithm and rules.
2. Collect Tag and MU messages
The working mode of an AP determines how it collects Tag and MU messages:
When the AP operates in monitor mode or hybrid mode, it can locate wireless clients or other
wireless devices that are not associated with it.
When the AP operates in normal mode, it can only locate wireless clients associated with it.
The wireless location system considers wireless clients associated with the AP as wireless clients,
and considers wireless clients or other wireless devices not associated with the AP as unknown
devices.
NOTE:
•
For more information about monitor mode and hybrid mode, see "WLAN security configuration."
• An AP operates in normal mode when it functions as a WLAN access point. For more information, see
"Configuring access services."
After the processes, the AP begins to collect Tag and MU messages.
• Upon receiving Tag messages (suppose that the Tags mode has been configured on the AC, and
the location server has notified the AP to report Tag messages), the AP checks the Tag messages,
encapsulates those passing the check and reports them to the location server. The AP encapsulates