In the last several years we have seen an explosion of consumer GPS products. Telematics systems, LBS applications on cell phones, GPS-enabled PDAs, and more novel GPS products such as pet finders have flooded the marketplace, with new products and applications announced almost daily. Likewise, public awareness of the potential utility of GPS has increased. Microsoft’s and Google’s entrance into the GPS and mapping market have helped accelerate consumer understanding and adoption of location technology. This is also causing a major demand among users of LBS technology to “show what is around me.” In a word, GPS is a general term in the marketplace to which consumers are accustomed in how they understand and explain all location-enabled products and applications. What’s interesting is that GPS is not even the positioning-enabling (or location-enabling) technology inside many of these new locationaware applications that are getting a lot of traction these days. Moreover, Google and the other online mapping consumer websites are a disruptive technology for GPS because they don’t require the use of GPS – users can either self provision by entering a street intersection or applications like Google Local and Microsoft Local Live use WiFi for location sensing to the nearest access point.

Today, there is a vast array of location technologies that are involved in the calculation of a user’s or object’s position in a space or grid, based on some mathematical model. Positioning here means allowing a mobile device to be aware of its location with different degrees of precision and accuracy. The technology required for provision of automated location information to mobile devices has been in continual development for several decades. While the majority has its roots in the military (e.g., GPS), modern consumer technology is also rising to meet the challenges, specifically in metropolitan areas. Telecommunications initiatives, like the U.S. FCC's E911 and Europe's E112, have generated a lot of interest in the potential for "Location Based Services" (LBS)--application and services that are a function of a person's or object's location.

Unfortunately, LBS fails because it does not work where people are: indoors and in cities. GPS is great, but not for many of the enduser (consumer-facing) and 'local' applications that will prove to be the backbone of the LBS market. That is, millions of square meters of indoor space and urban areas are out of reach of GPS systems. Conventional GPS
receivers do not work inside buildings due to the absence of line of sight to
satellites, while cellular positioning methods generally fail to provide a satisfactory degree of accuracy, resulting in a greater part of the world’s commerce and social interaction that is being conducted indoors not being able to take advantage of outdoor positioning systems like GPS. The delivered position fixes cannot even be used for determining whether a target person stays inside or outside a certain building, not to mention that it is by no means possible to locate it with the granularity of rooms or floors.

A multitude of applications and services can benefit from indoor (in building) positioning and navigation such as logistics, routing, sales, asset tracking, personal safety, and emergency response (e.g., Department of Homeland Security’s advanced 3D locator system), as well as consumer handset LBS applications. With the last, locationbased advertising is a good example, where vendors care about building a closer relationship to the potential consumer. Google, with billions of dollars in annual revenue generated through targeted ads associated with online searches, might be able to improve the economics of such plans via location-based advertising.

Fortunately, over the past decade, advances in location positioning technology have made it possible to locate users and objects indoors (locally; i.e., in urban centers and inside buildings). These alternative technologies are now being introduced to the market, enabling many kinds of indoor location-aware applications. Different technologies will demand different capabilities from devices, while they bring various constraints. Outside the remit of 2G, 2.5G, 3G, and 4G cellular networks exist other families of positioning technologies that are often referred to as “local positioning”, which make use of short-range networks such as 802.11, Bluetooth, RFID, ultrasound, UWB, IrDA, or TV radio signals.

Indoor positioning and tracking applications are not just a vision or found only in the lab. The potentials of location-aware indoor applications were realized in the early 1990s. They were explored in conjunction with research on ubiquitous/sentient computing. Indoor environments present opportunities for a rich set of location-aware applications such as navigation tools for humans and robots, interactive virtual games, resource discovery, asset tracking, location-aware sensor networking, and others. Further, typical indoor applications require different types of location information such as physical space, position, and orientation.

Indoor location-aware applications require micro-detailed geo-referencing to satisfy users’ growing needs. It is not enough to geo-reference a building if the position of users and other objects inside the building are also relevant. Objects are used as landmarks, and relationships among the objects are crucial for symbolic representation of the whole system.