Ten Things You Need to Know About Indoor Positioning

May 6, 2013

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1. GPS does not work well indoors

While today’s more sensitive GPS chips can sometimes get a fix (receive signals from enough satellites to determine a location) inside a building, the resulting location is typically not accurate enough to be useful. The signals from the satellites are attenuated and scattered by roofs, walls and other objects. Besides, the error range of many GPS chips (tennis court) can be larger than the indoor space itself (small grocery store)!
2. Some indoor positioning solutions work similar to GPS
Locata, an Australian company, offers beacons that send out signals that cover large areas and can penetrate walls. Locata receivers work similarly to how GPS receivers work. The U.S. Department of Defense is an early Locata user.
Nokia uses beacons that send out Bluetooth signals. While any Bluetooth device can read them, they only cover a few square meters. Nokia last year set up the In-Location Alliance with 22 companies to further develop a Bluetooth locating solution (press release).
Many companies tap into Wi-Fi signals that are all around us - including when we are indoors. With a good map of the locations of the access points, a Wi-Fi receiver like a cell phone can be located even indoors (Wikipedia). Google, Navizon and Skyhook are among the leaders in this area.
TruePosition, which offers a cell tower locating solution, acquired the intellectual property of Rosum (APB coverage). Rosum taps TV signals for location determination.
3. Other solutions use light or magnetic fields to determine location
ByteLight sends flickering light patterns from its LED light fixtures. The receiver (a camera on a phone) reads the code and sends it to a server. On the server the code is compared to those a map. A match means the receiver is under a specific “light.” 
IndoorAtlas, a start-up based in Finland, surveys buildings for their internal magnetic map. The fields vary within the structure, providing different fingerprints for different locations. A cell phone’s internal digital compass can be used to detect the field and, much like ByteLight’s procedure, compared to the map for location determination (Economist coverage).
4. RFID and inertial systems work very differently
Passive radio frequency identification tags (RFIDs) prompt a transaction when they pass near a sensor. For example, a closed door prompts the user to swipe the card to pass. Doors or gates force users into a queue or to slow down for the sensor to work properly. These passive systems detail only that a person or object entered a room; they do not provide detailed location information within the room.
Active RFID tags are self-powered and regularly send out signals to receivers within the area of interest. This is the reverse of GPS. Knowing the location of the receiving sensors allows for accurate indoor locating in near real-time.
Solutions that use inertial measurement work only if a starting location is know. With that information collected, these sensors use accelerometers, gyroscopes and other sensors including clocks to track orientation and distance to keep track of location in near real-time. The latest inertial solution, from DARPA, is a chip smaller than a penny (press release).
5. Indoor positioning detects the location of a person or object, but not always its orientation or direction
While indoor positioning systems can determine location, many need additional information to determine which way a person or object is facing. That can make providing directions or pitching a product in a store more challenging. 
The addition of an electronic compass to a receiver (many cell phones now have them), or a microelectromechanical systems (MEMS) orientation sensor or a prompt to turn toward a particular direction (to scan a bar code or QR code on a poster, for example) can provide more information regarding orientation.
6. The best solution for indoor and outdoor positioning may be a hybrid
No single solution works perfectly in all environments. For that reason devices may support more than one positioning solution and switch between them as needed. Today’s mobile phones use GPS (when it’s turned on) outdoors but may switch to Wi-FI positioning (when it’s turned on) when the signal is weak, such as when an individual goes indoors. Indoor location and commerce solution provider aisle411 taps into both Wi-Fi and MEMS sensors for its retail store offerings.
7. Indoor positioning is in demand for a variety of uses
While the goal of indoor positioning for some users, notably hospitals and malls, is to provide navigation aid, others want to use indoor positioning to better market to customers, provide just-in-time information via audio for tours, offer video or augmented reality experiences or connect people of interest in proximity to one another. The U.S. Federal Communications Commission hopes to use indoor positioning to provide timelier and more effective emergency services (see below).
8. Major tech players are working in the indoor space
Apple, Google and Microsoft are all exploring the use of indoor positioning. At this time the effort is focusing on both indoor positioning technologies and creating the basemaps that will make such solutions more valuable.
Google has its own Android positioning system based on Wi-Fi (APB coverage). When some Android developers (Samsung, Motorola) tried to use Skyhook’s solution in place of Google’s, Google sued. That case will be in court, along with a few others, in 2014 (FOSS Patents coverage). Microsoft uses Wi-Fi for indoor positioning, as well, and has some research going on regarding the use of signal strength for location determination. Apple recently acquired WifiSLAM (APB coverage) to get into the indoor location game.
9. The Federal Communications Commission (FCC) is looking at indoor positioning to enhance emergency response
Results of a study conducted in late 2012 and published March 14, 2013 by the FCC’s Communications Security, Reliability and Interoperability Council (CSRIC) suggests a current baseline for indoor positioning for use in emergency response. Three different vendors, using three different indoor technologies, participated (summary).One key concern is determining vertical location, that is, on which floor a person is standing in a multilevel building. The FCC report concludes: “While the location positioning platforms tested provided a relatively high level of yield, as well as improved accuracy performance, the results clearly indicate additional development is required.”
10. Indoor positioning requires indoor maps
Locating a person or device indoors is only half of the solution. For the location to be meaningful for navigation or other purposes, service providers need accurate indoor maps. There’s a new industry creating those data. Micello recently announced it had mapped 15,000 indoor venues (press release). Google, in addition to collecting its own indoor mapping data (APB coverage), is crowdsourcing maps from its proprietors (APB coverage). Nokia (APB coverage) is collecting indoor data and even OpenStreetMap has a wiki page about indoor maps.

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