RTLS and Indoor Positioning Systems

RTLS and indoor positioning systems have many similarities. The differences in the systems involve the technology used and the purpose of the system. Most indoor positioning systems use Bluetooth beaconing. Some systems utilize Wi-Fi, but, Wi-Fi is less accurate. The tag used in indoor positioning is a person's smartphone. A ubiquitous type tag may be less secure, depending on the mode of communication between the tag and the Bluetooth beacon.

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The purpose of indoor positioning is to locate an individual or count people within a space. You can also use indoor positioning for business purposes. For example, an indoor positioning system in a shopping mall may communicate to mall shoppers via the individual's smartphone with a coupon from one of the retail stores.

Studies have found that people spend 80-90% of their time indoors, so it's no surprise that one of the most promising technologies for buildings is Indoor Positioning Systems (IPS). An IPS is just a data acquisition system, obtaining information as to location of people or objects within the building, providing data to occupants to assist in wayfinding. It has more potential uses, such as providing valuable information to businesses and building owners, security and life safety functions, and yet in some cases present some legitimate concerns.

Many people are familiar with Global Positioning Systems (GPS). GPS depends on satellites; its use indoors is affected by roofs, walls, and objects in the building resulting in the attenuating, weakening, reflecting, or scattering the radio waves from satellites. While typical GPS may not be suitable for indoor, use GPS and indoor positioning systems can be integrated. Also, some GPS have enhanced the sensitivity and power of their receivers (high sensitivity) and are able to receive some, satellite signals within a building.

Indoor Positioning Systems also have some similarities with Distributed Antenna Systems (DAS) that boost cell phone coverage in buildings. The IPS uses cellphone apps to allow users to navigate through a building and can use cellphone capabilities likeBluetooth to locate the cell phone users. Unlike the real time location systems (RTLS) where corporate users (hospitals, warehouses) bought a system, the DAS deployments are usually business deals between the building owner and local cell carrier. Building owners want to satisfy the needs of their tenants, and the cell carriers want to increase usage. It's likely the indoor positioning systems will involve a commercial arrangement similar to DAS. Questions and concerns will arise about who will manage the system, who pays for what, who owns the data, who profits, privacy and security concerns, and who maintains and upgrades the system.

One approach to the IPS architecture is Bluetooth Beaconing. Bluetooth was created in 1994 to replace short cables. Today every smartphone is Bluetooth-enabled and we're all familiar with using Bluetooth to connect ear buds, headsets, printers, game consoles, and keyboards. It is the Bluetooth capabilities of smartphones together with the Bluetooth beacons that can provide the location of smartphone users. In 2010 Nokia introduced an indoor positioning system based on Bluetooth Low Energy (BLE) technology (basically the latest Bluetooth technology operating on low power with low latency in communications). The density of the Bluetooth beacons is roughly the same as a typical Wi-Fi deployment, with accuracy around 0.3 meters (1 foot), with no latency.

There appear to be two general approaches for the Bluetooth beaconing: one where the smartphone pulls data from beacons; the other just the opposite, where the beacons pull information from the smartphones. Several experts believe the first approach is a better plan for privacy and data security. The second approach, with beacons detecting the smartphone, eliminates the need for specialized software on the smartphones and is passive for the smartphone.

While Bluetooth Low Energy (BLE) beacons may be the most widely used technology for indoor position systems, there are other existing technologies. These include Wi-Fi, which is less accurate that Bluetooth. Newer technologies are starting to be developed; these include LED lighting that emits modulated light specific to an indoor location, reading the Earth's magnetic field energy, and embedding different sensors in smartphones. Wi-Fi and Bluetooth BLE are the most common technologies for most IPS deployment.

The IPS system will use a variety of methods including triangulation, signal fingerprinting, and direct association:

b Triangulation: Most people understand that cell towers and GPS determine locations based on the distance between a person and at least three radio devices such as Wi-Fi access points or BLE beacons, all of which are known locations. The potential issue here is interference; walls, and large objects such as equipment. IPS fingerprinting overcomes the interference problems of triangulation.

b Fingerprinting-based system: This method requires capturing radio signals, such as Wi-Fi or Bluetooth beacons, from a smartphone in spaces within a building. Each sampling of radio signals in a specific room

Blue beacons

Figure 9.3 Blue beacons.

creates a fingerprint. Once organized, the IPS can be probed, and the system will have the data and analytics to determine the user's location.

b Direct Association: This method works based on the addresses or unique identifiers of Wi-Fi access points or Bluetooth beacons. For Bluetooth, an application on a smartphone apprehends this identifier and the IPS can locate the device. Wi-Fi networks are a bit different because there are multiple access points. Each access point has a Basic Service Set Identifier. The Indoor Positioning System uses analytics to determine signal strength between any access point and a smartphone to estimate the smartphone's location.

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