Abstract
The provisioning of Location-Based Services (LBS) follows the chain of determination of a position, mapping this information onto a natural language-based description of this position and performing the service itself. The evolution of technologies regarding applications and infrastructure, standards and contents has brought up various streams that have influenced the development of this chain over the past years (Zeimpekis et al., 2003). On the one hand, emerging theoretical concepts have been showing the way for many commercial and non-commercial services. On the other hand, the conceptual evolution has been accompanied by significant investments of mobile technology companies and service providers to the further development of practical solutions (Gessler and Jesse, 2001).
TopLocation-Adapted Services
LBS provide users of mobile devices personalized services tailored to their current location. These central information services fall into three broad categories that also emphasize the added value for consumers: positioning and location identification, contextual and environmental location information as well as navigation between different locations.
There exists a vast body of literature on positioning technologies reaching from the early Active Badge indoor locating solutions to the Global Positioning System (GPS) and the more recent Wireless Local Area Network (WLAN) and Bluetooth concepts (King et al., 2006).
The diversity of the underlying technological basis as well as the opportunities and limitations among these approaches in design and characteristic means of data networks correspond to the increasing need for adapted LBS infrastructures. These are tailored to the specific requirements of different types of locations, different modes of mobility and distance (Zeimpekis et al., 2003).
The precision of location information and the distance of a mobile device to a Location Service Provider (LSP) are two factors that play a key role in this context. They present the overall framework in which the service layer of key features of applications and infrastructure technology is embedded.
Key Terms in this Chapter
Location Service Provider (LSP): A provider of a value-adding service, which is dependent on location information.
Time of Arrival (TOA): The position of a device can be determined by measuring the transferring-time of a signal between the device and the COO.
Time Difference of Arrival (TDOA): Determining a more precise position information of a device by taking advantage of a cells infrastructure and measuring the transferring time of a device to three or more antennas.
Cell Of Origin (COO): In a traditional communication environment a COO is referred to as the cell or tower, a handset device is tied to.
Ubiquitous Information Management (UIM): A communication concept, which is free from temporal and, in general, from spatial constraints.
Ultra Wideband (UWB): A technology which enables very short-range positioning information.
Bluetooth Indoor Positioning Service (BIPS): A symbolic location technology based on proximity to known objects.
Enhanced Observed Time Difference (EODT): Reversing the TDOA-principle, EOTD measures the transferring-time of signals from the towers to the device.