H3C Technologies H3C WX3000E Series Wireless Switches - Manual (Page 739)

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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 include Tags (small, portable RFIDs, which are usually placed or
glued to the assets to be located) of a location server company or Mobile Units (MU), and MUs
(wireless terminals or devices running 802.11). The tags and MUs can send wireless messages
periodically.
• Location information receivers include 802.11 APs.
• Location systems include the location server, calculation software of a location server company, and
different types of graphics software.
Wireless location method
Before locating wireless devices, configure a wireless location method in either of the following methods
so that the AP can get an IP address of the location server:
• Dynamic wireless location—The AP gets an IP address of the location server from packets sent from
the location server. Only location servers of AeroScout support this method.
• Static wireless location—An IP address of the location server is manually configured on the AC.
Wireless locating process
A wireless location system can locate wireless clients, APs, rogue APs, rogue clients, Tags and other
devices supporting WLAN protocols. All wireless devices except Tags 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 periodically sends location messages on channels 1, 6, and 11, in turn.
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. The filtering is done by the location server,
according to a certain algorithm and certain 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 normal mode and is bound to an enabled wireless service, it can
locate wireless clients associated or not associated with it or other wireless devices, including
Tags. 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.
When the AP operates in normal mode and is not bound to any wireless services or the wireless
service is disabled, it can only locate wireless clients not associated with it or other wireless
devices.