Bringing Location and Navigation Technology Indoors
by George Lawton
Location and navigation technologies have become popular, with demand steadily increasing for improved approaches to driving from one place to another. Now, researchers and vendors are starting to work on these technologies for indoor use.
"Our vision is that location has to become part of day-to-day life, not just when we navigate. This is where indoor location concepts entered into our thinking," said Kanwar Chadha, chip vendor CSR's chief marketing officer.
These techniques promise to improve navigation in large indoor spaces such as convention centers and airports, as well as improve the ability to find products in a store. They could also make it easier for people to find one another inside large facilities.
Although some vendors are starting to offer indoor navigation and mapping products, the technologies face two key challenges.
The GPS signals used for outdoor navigation don't always penetrate through building walls, so other location-sensing technologies are required for indoor accuracy.
Also, no standards exist for storing, managing, and viewing indoor map data, which makes it more difficult to usefully create and share maps, said Ankit Agarwal, indoor-mapping vendor Micello's CEO.
Introducing Indoor Navigation
Researchers and vendors began thinking about creating indoor mapping tools in the late 1990s, once MapQuest demonstrated digitized outdoor maps' benefits, said Agarwal. In 2002, the Map Network launched its service, which featured maps of select indoor venues. The company — which mapping and geographic-data vendor Navteq acquired in 2007 — also developed tools and a database for managing the maps.
The early indoor maps were Web-based and contained large amounts of data.
In 1999, associate professors Andrew Golding of Stanford University and Neal Lesh of the University of Washington demonstrated that indoor navigation systems could achieve accuracy by fusing data from accelerometers, magnetometers, and light sensors. At the time, though, there wasn't enough indoor map data to make these approaches useful.
More recently, vendors such as Broadcom and CSR have begun working on embedded smartphone chipsets for gathering indoor location data from GPS signals, Wi-Fi and other radio-based sources, and additional types of sensors such as gyroscopes.
With the growth of smartphones, several indoor-navigation vendors — including FastMall, Micello, and Point Inside — launched indoor mapping databases and services in 2008 and 2009.
Other vendors such as BuildingLayer and Meridian recently introduced tools for making indoor maps that can be displayed on smartphones.
Last year, Google, Microsoft, and Navteq announced indoor-mapping support such as the ability to upload and serve indoor-map data.
Outdoor navigation depends on satellite-based technologies such as the US's GPS. The systems triangulate signals from satellites to determine a user's location.
While GPS works well outdoors, buildings or even heavy vegetation tend to block some or all of the signals.
Broadcom and CSR are adding circuitry for receiving other satellite-based navigation systems such as Russia's GLONASS, China's Compass, and the EU's Galileo. Using these systems could enable devices to accurately identify locations when there aren't enough GPS signals available, Chadha explained.
A second strategy uses other stronger or more localized radio sources — such as cellular-phone, Wi-Fi, and Bluetooth signals — to improve indoor navigation. For example, a system could leverage received Wi-Fi signals and information about the location of base stations to perform triangulation and determine where a user is.
CSR is working on the SiRFstar V architecture for improving indoor navigation. The first hardware-based implementation will be in a special chip — installed in a phone — that can gather and correlate raw data from multiple satellite systems, as well as from Wi-Fi, Bluetooth, and microelectromechnical-systems (MEMS) sensors. CSR also plans to release its software so that users can download it to their mobile phones.
While these approaches use existing equipment, another would require building owners to deploy Bluetooth signaling beacons throughout their facilities. Bluetooth-equipped devices could then conduct triangulation for location identification. Vendors such as Nokia are working on beacons that use Bluetooth 4.0, the technology's most recent version, to send signals that mobile devices can use.
However, Chadha said, radios like those in Bluetooth and Wi-Fi are engineered for communications and frequently have higher variations in clock timing than other radios. This provides less precision, which makes accurately triangulating locations more difficult.
In Japan, another radio-based approach deploys ground-based GPS beacons, which augment the satellite-based system for calculating location. However, most countries prohibit land-based beacons that transmit on GPS frequencies because they could interfere with satellite-based GPS signals.
MEMS sensors could improve location accuracy when some or all satellite signals are lost. A smartphone could use 3D accelerometers to capture data about the phone's movement through space, and use gyroscopes and compasses to collect information about the device's rotation. This leads to more precision.
However, Chadha noted, these systems work for only short periods because they experience small errors that add up over time. To maintain consistent accuracy, these systems must be recalibrated regularly via GPS, Wi-Fi, or Bluetooth updates.
Mapping companies create outdoor maps by driving around streets with specially equipped vehicles. Mapping indoor facilities is less straightforward because it requires the permission and cooperation of the owner of, for example, a convention center or large store.
The work typically involves creating a basic map of a facility with overlays representing specific exhibitors or shops.
Until recently, systems created and accessed indoor maps using proprietary specialized mapping applications. Each system thus required its own application.
Now, though, indoor-mapping databases from major navigation vendors such as Google, Microsoft, and Navteq let companies create indoor maps that integrate more easily with multiple mainstream mapping and navigation systems.
Outdoor maps focus on finding a user the shortest path to a destination. On the other hand, Agarwal stated, indoor maps could be useful for finding products of interest in a large store, identifying the most efficient route for picking up items on a shopping list, locating friends in large venues, and helping disaster-response personnel work within buildings. They could also let stores offer products to people passing nearby or better organize their aisle layout, he said.
Aisle 411 has developed an application that lets retailers record where items are in their store and is in the process of creating indoor maps and databases that include product locations.
Glympse has developed Android and iPhone apps that allow users to share their location with a friend or colleague for a limited period of time. This makes finding friends during a meeting easier, while maintaining a user's privacy after the event ends.
Indoor navigation and mapping faces several obstacles.
For example, using data from multiple vendors' sensors and radios in different phones can be challenging.
Many phone platforms gather data and make it available for mapping applications in different ways, necessitating a separate API for each platform, Chadha said.
Although some third-party applications can incorporate data from multiple sensors, the necessary preprocessing in some cases causes delays in delivering results, which often makes location information no longer current, he noted.
There are also subtle delays and variations in the ways devices and their operating systems capture and process sensor signals. This slows the delivery of data for triangulation, which reduces the process' precision.
Using Bluetooth beacons could enable better navigation by smartphones. However, facility owners will have to make significant investments to deploy and maintain the beacons, said David Allen, location vendor Locaid's chief technology officer.
Making indoor maps is also challenging because property owners must agree to, help with, and fund the process, which they won't do if not convinced of its value.
Applications don't have a standard way to collect and manage map data. Thus, map owners must convert the data into a format compatible with each mapping application they want to work with.
Indoor location technology sometimes experiences problems with multistory buildings, said Agarwal. Indoor location apps aren't always precise enough to accurately identify which floor of a structure a user wants to navigate.
Navigating the Future
Navigation was the killer app for outdoor location services, noted Nick Brachet, location-vendor Skyhook's chief technology officer. However, Brachet said, the technology may not be used that way indoors.
For example, the turn-by-turn, street-by-street directions employed in outdoor navigation would not be as useful indoors, where aisle numbers or other landmarks could be more helpful.
Chadha said the services may be particularly popular for use with navigating malls, trade shows, product promotions, and emergency services.
In the long run, Agarwal predicted, most indoor-location services will be implemented within mobile devices. This would make the services available to all consumers with properly equipped devices without requiring the involvement of facility owners.
However, Agarwal said, it could take three years before vendors deploy the technology in devices and large numbers of consumers buy them.