Location-Based Services

Location-based services (LBSs) have emerged primarily due to the availability of, and the possibility of coupling, “location,” “mobility,” and “context” information. Of these, location and mobility play central roles, and context describes the environment for the process of decision making in LBSs. LBSs are different from conventional geographic information systems (GIS) in that they feature mobility and the possibility of position determination while mobile. In other words, spatial decision making in LBSs is based on mobility and position, which involves dynamic locations of people and objects. An example of LBS is a navigation system in which a user's location (“location”) is continuously (“mobility”) computed for the purpose of finding routes (“context”), among other things. LBSs, in general, could provide answers to questions such as the following:

• Where am I located at any given time with respect to another given location?
• Where are the locations of given people/objects with respect to my current location?
• Where is the nearest location of a specific person/object with respect to my current location?
• Is my location within a given proximity to a certain person/object?

As is clear from the above questions, LBSs must be able to provide “location” and “mobility” information and use them in a “context” to reason and make decisions.

Figure 1 highlights the types of features LBSs support and the types of technologies they use. The green circle highlights the features typically supported by LBSs, which include localization, [Page 1795]mobility, accessibility, visualization, scalability, and spatiotemporal modeling and analysis. The localization feature is for finding a user's location, which could be requested at fixed intervals or on the fly. It is worth noting the difference between position and location, as well as their relation to localization in general. By position, we refer to coordinates (e.g., latitude and longitude) as computed by a positioning technology. By location, we refer to a place to which the position belongs. For example, the coordinates of a car as determined by a navigation system give the position of the car and the road segment constituting the location of the car. The access feature is for accessing information and functionality remotely from the user's current location. The visualization feature is for presenting location and context in a meaningful way to the user. The scalability feature guarantees solutions with acceptable response times regardless of how much information is being computed for decision making. For example, a task in one location may require a much larger amount of data for computation and visualization than would be needed in another location. The spatiotemporal modeling and analysis support efficient reasoning and decision making at a given location and within a user-specified context.

Figure 1 LBS features and technologies

Source: Author.

The blue circle in Figure 1 highlights the common technologies on which LBSs are based. Each category of technologies is for implementing one [Page 1796]of the features in the green circle. Geopositioning technologies are for implementing the localization feature—that is, finding the position and location of people and objects. The types of geo-positioning technologies used in LBSs include global positioning system (GPS), radio frequency identification (RFID), and Wi-Fi, among others. Most such technologies provide position information that, depending on the application/service at hand, could be converted to location. Mobile devices are used for implementing the mobility feature and include primarily personal digital assistants (i.e., handheld computers) and cell phones, especially smart phones. Wireless communication allows LBS users to access data and other relevant resources remotely from various sources, such as LBS providers and third-party vendors. Mapping is a predominant form of visualizing information. Infrastructure refers to the underlying set of platforms and components required for the LBS. One example of such a LBS platform would be the Android system by Google. GIS, general purpose and specialized, is used for spatiotemporal modeling and analysis and for developing or customizing tools to support LBS decision making.

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