Installation guide

20
Wi-Fi Location-Based Services—Design and Deployment Considerations
OL-11612-01
Cisco Location-Based Services Architecture
Cisco RF Fingerprinting offers several key advantages over traditional approaches:
• Uses existing LWAPP-enabled Cisco Unified Networking Components—Unlike some other
solutions, Cisco LBS with RF Fingerprinting is a 100 percent Wi-Fi RTLS without the need for
specialized time-based receivers or other specialized hardware. The Cisco Location Appliance is
added to support location and statistics history and serves as a centralized positioning engine for the
simultaneous tracking of up to 2500 devices per appliance.
• No proprietary client hardware or software required—The Cisco RF Fingerprinting-based LBS
solution is implemented as a network-side model and not client-side. Because of this, Cisco RF
Fingerprinting can provide location tracking for a wide variety of industry-standard Wi-Fi clients
(not just WinXP/2000/PPC) without the need to load proprietary client tracking software or wireless
drivers in each client. This includes popular VoIP handsets such as the Cisco 7920 and others,
devices for which proprietary location tracking client software is not readily available.
• Supports popular Wi-Fi active RFID asset tags—Because the Cisco LBS solution implements RF
Fingerprinting as a network-side model, there is no dependency on proprietary software being
resident in RFID asset tags. This enables the Cisco LBS solution to interoperate with active RFID
asset tags from popular vendors including AeroScout and PanGo Networks. Cisco also makes
available a complete RFID tag specification to Cisco Technology Partners and encourages the
development of interoperable active RFID tag hardware. The Cisco LBS solution is capable of
tracking other Wi-Fi active RFID tags that can be configured to authenticate/associate to the
underlying installed Cisco centralized WLAN infrastructure as a WLAN client.
• Better accuracy and precision—The Cisco RF Fingerprinting approach yields significantly better
performance than solutions employing pure triangulation or RSS lateration techniques. These
techniques typically do not account for effects of attenuation in the environment, making them
highly susceptible to reductions in performance. The advantages of Cisco RF Fingerprinting
technology start where these traditional approaches leave off. Cisco RF Fingerprinting begins with
a significantly better understanding of RF propagation as it relates specifically to the environment
in question. With the exception of the calibration phase in location patterning, none of the traditional
lateration or angulation approaches discussed in Distance-Based (Lateration) Techniques, page 8
and Angle-Based (Angulation) Techniques, page 14 take environmental considerations directly into
account in this manner. RF Fingerprinting then goes a step further, by applying statistical analysis
techniques to the set of collected calibration data. This allows the Cisco Location Appliance to
further refine predicted location possibilities for mobile clients, culling out illogical or improbable
possibilities and refining accuracy. The net result of these efforts is not only better accuracy but
significantly improved precision over traditional solutions.
• Reduced calibration effort—The Cisco RF Fingerprinting technology offers the key advantages of
an indoor location patterning solution but with significantly less effort required for system
calibration. Although both solutions support on-site calibration, the Cisco RF Fingerprinting
approach offers less frequent re-calibration and can operate with a larger inter-access point spacing
than location patterning solutions. Cisco RF Fingerprinting can also share RF models among similar
types of environments and includes pre-packaged calibration models that can facilitate rapid
deployment in typical indoor office environments.
Overall Solution Architecture
The overall architecture of the Cisco LBS solution can be seen in Figure 8: