Location-Based Services (LBS)

LBS Applications

The development of LBS thus far has coincided with advances in geographic information technologies coupled with the proliferation of wireless communications. In the United States, these efforts have been largely stimulated by the Federal Communications Commission's Enhanced-911 (E911) mandate. E911 requires wireless cellular carriers to develop capabilities to position users according to predefined accuracy standards as a means of improving the delivery of emergency services. These requirements exceeded the location positioning capabilities of most wireless carriers at the time, requiring a considerable investment in improving the positioning infrastructure. LBS development largely represents an attempt to leverage the required investment in positioning technologies to achieve commercial gain. Similar efforts have transpired in the European Union with the Enhanced-112 (E-112) initiative.

[Page 268]Commercial LBS applications differ from traditional GIS applications in that they generally appeal to a broad base of nonexpert users that share structured, repetitive tasks. Perhaps the most commonly provided example is the use of LBS to improve wayfinding and activity scheduling for users in unfamiliar environments. These services might help users to identify where they are, what is around them, and the route they might take to arrive at a desired destination. Optionally, users may also wish to identify the locations of friends and colleagues. Other commercial opportunities include location-based advertising, location-based games, and asset tracking.

These commercial services can be classified according to when a user's location information is used by an application. Pull services, also known as user-requested or immediate services, use location information only when a service requested by a user requires it. Possible examples include requests for maps or driving directions. This process can be conceptualized in the same manner as the request-response architecture of the Internet. Push services, also known as triggered services, listen for specific events, such as a user traversing a given section of space. Sample applications include a retailer sending digital coupons to users proximal to store locations.

It is commonly assumed that the spatial operations and data required to complete these tasks, for example, a shortest-path or point-in-polygon operation, as well as the data required to support them are already provided by standard GIS functions. However, these resources are often fragmented among disconnected proprietary systems. A number of standardization efforts, such as the Open Geospatial Consortium's Open Location Services (OpenLS) initiative, have been proposed to define the core services and functions that are expected to be required to satisfy most LBS applications. These services act as primitive operations to support more comprehensive applications. The OpenLS defines five core services that “wrap” existing GIS functionality using standard markup interfaces, such as the Simple Object Access Protocol (SOAP). Most applications begin with a gateway service that provides a standard mechanism for querying the location of a user from a device or wireless carrier. The resulting location may be represented as a singlepoint location or an area of interest, to reflect the uncertainty involved with positioning the user. To make this locational information more meaningful, location utility services provide geocoding and reverse geocoding functions for translating between street addresses and geographic coordinates. The location may be given additional meaning by relating it to the surrounding environment with directory and routing services. Directory services provide users with online directories to assist in finding specific places, products, or services or ranges of places defined by a proximal distance threshold. Route services provide a route between two given points, with options to include specific way points in between. Routes can be generated to minimize either distance or time and can be specified according to a particular mode of travel. Presentation services provide the functions to visually communicate this information on maps.

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