Руководство По Проектированию для Cisco Cisco Aironet 350 Mini-PCI Wireless LAN Client Adapter
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Enterprise Mobility 4.1 Design Guide
OL-14435-01
Chapter 13 Cisco Unified Wireless Location-Based Services
RFID Tag Considerations
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Minimizing excessive co-channel interference—In many cases, location-based services are added
or retrofitted to an existing wireless design, some of which encompass VoWLAN handheld devices
(such as the Cisco 792x). When designing a location-aware solution to be used in conjunction with
latency-sensitive devices, special care needs to be taken to ensure that excessive co-channel
interference is not introduced into the environment. In cases such as this, the needs of an optimal
location-aware design must be carefully balanced against the requirements of a properly designed
wireless voice infrastructure.
or retrofitted to an existing wireless design, some of which encompass VoWLAN handheld devices
(such as the Cisco 792x). When designing a location-aware solution to be used in conjunction with
latency-sensitive devices, special care needs to be taken to ensure that excessive co-channel
interference is not introduced into the environment. In cases such as this, the needs of an optimal
location-aware design must be carefully balanced against the requirements of a properly designed
wireless voice infrastructure.
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Avoiding location display “jitter”—At times, devices appear to move on location displays even
though they are known to physically be at rest. This can be due to a variety of factors, including the
movement of surrounding objects in the environment and slight changes in the orientation of the
client and the client’s antenna system over time. Location smoothing is used to assist in
counteracting this phenomena and stabilize location jitter for clients that are not in constant motion.
though they are known to physically be at rest. This can be due to a variety of factors, including the
movement of surrounding objects in the environment and slight changes in the orientation of the
client and the client’s antenna system over time. Location smoothing is used to assist in
counteracting this phenomena and stabilize location jitter for clients that are not in constant motion.
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Multi-domain design considerations—The Cisco Wireless Location Appliance can provide
simultaneous tracking for up to 2500 total devices, which includes WLAN clients, asset tags, rogue
access points, and rogue clients. In most cases, a single location appliance and WCS management
system should suffice for the majority of applications. However, in larger networks, it may be
necessary to use either a single WCS server with multiple location appliances or multiple WCS
servers with one or more location appliances.
simultaneous tracking for up to 2500 total devices, which includes WLAN clients, asset tags, rogue
access points, and rogue clients. In most cases, a single location appliance and WCS management
system should suffice for the majority of applications. However, in larger networks, it may be
necessary to use either a single WCS server with multiple location appliances or multiple WCS
servers with one or more location appliances.
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Antenna considerations—A discussion of supported antenna combinations for use with the
location-aware Cisco UWN, tips on third-party antennas, and antenna orientation best practices.
This section includes information on the newly-introduced (in Release 4.1 of the Cisco UWN)
antenna vertical height and azimuth capability, which allows the vertical height and x-axis angular
offset of access point antennas to be specified in WCS when placing access points on WCS floor
maps.
location-aware Cisco UWN, tips on third-party antennas, and antenna orientation best practices.
This section includes information on the newly-introduced (in Release 4.1 of the Cisco UWN)
antenna vertical height and azimuth capability, which allows the vertical height and x-axis angular
offset of access point antennas to be specified in WCS when placing access points on WCS floor
maps.
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Site calibration—Post-deployment location calibration can be performed if location accuracy using
one of the included calibration models is lower than expected or if the target environment is complex
and not well represented by one of the included models. During this calibration, an 802.11 wireless
client device is used to take RSSI measurements in the environment. The measured RSSI is then
used by the location appliance to fine-tune the path loss model assigned to the environment, which
typically leads to improved accuracy and precision. This section contains important tips on
performing site calibrations, calibration validity, choosing a calibration client, and improving
overall calibration performance. The benefits of performing calibrations using clients compatible
with the Cisco Compatible Extensions for WLAN clients specification version 2 or higher are also
discussed in detail in this section.
one of the included calibration models is lower than expected or if the target environment is complex
and not well represented by one of the included models. During this calibration, an 802.11 wireless
client device is used to take RSSI measurements in the environment. The measured RSSI is then
used by the location appliance to fine-tune the path loss model assigned to the environment, which
typically leads to improved accuracy and precision. This section contains important tips on
performing site calibrations, calibration validity, choosing a calibration client, and improving
overall calibration performance. The benefits of performing calibrations using clients compatible
with the Cisco Compatible Extensions for WLAN clients specification version 2 or higher are also
discussed in detail in this section.
RFID Tag Considerations
The majority of RFID tags currently produced commercially are passive RFID tags, consisting basically
of a micro-circuit and an antenna. They are referred to as passive tags because they are actively
communicating only when they are within the electromagnetic field of a passive RFID tag reader or
interrogator.
of a micro-circuit and an antenna. They are referred to as passive tags because they are actively
communicating only when they are within the electromagnetic field of a passive RFID tag reader or
interrogator.
Another type of common RFID tag in the current marketplace is known as the active RFID tag, which
usually contains a battery that directly powers RF communication. This onboard power source allows an
active RFID tag to transmit information about itself at great range, either by constantly beaconing this
information to a RFID tag reader or by transmitting only when it is prompted to do so. Active tags are
usually larger in size and can contain substantially more information (because of higher amounts of
memory) than do pure passive tag designs.
usually contains a battery that directly powers RF communication. This onboard power source allows an
active RFID tag to transmit information about itself at great range, either by constantly beaconing this
information to a RFID tag reader or by transmitting only when it is prompted to do so. Active tags are
usually larger in size and can contain substantially more information (because of higher amounts of
memory) than do pure passive tag designs.