Location Information and Context Awareness
One particular characteristic of the mobile Internet is obviously that users are mobile—that is, not bound to a particular location. The location of users can be used for a number of location-based services, ranging from finding the nearest pizza parlor through turn-by-turn driving directions to finding a person that makes an emergency call.
Many modern devices contain a Global Positioning System (GPS) chip for providing location information. GPS is, however, not very accurate indoors or in the presence of buildings. Therefore, in many networks, additional ways of positioning a mobile terminal are used.
Location information is, however, just one example of the broader issue of context awareness. Knowledge about the network, the device that accesses the network, the user, and the applications can all be leveraged to offer the user a tailor-made user experience. But that is beyond the scope of this book.
The following paragraphs explain how location is determined in LTE and Wi-Fi networks.
Location Information in LTE
Nowadays many mobile devices contain a GPS receiver. This allows the applications to acquire the location of the device and offer services based on that location. In addition to that, many devices are able to use so-called assisted GPS (A-GPS) to overcome the inaccurate indoor positioning of GPS. With A-GPS, the network supplies location information (based on the position in relation to cell towers) or information about the geo-orbital position of the GPS satellites. This allows devices to acquire fast and reliable positioning information in all circumstances, even indoors. This is of particular importance in emergency situations (like 911 or 112 calls in, respectively, the United States and Europe).
Location Information for Wi-Fi Networks
Unlike in cellular systems, where there are relatively few radio towers of which the position is well known, for Wi-Fi networks, the location of all access points is not always well known and might change. This makes it comparatively harder to use the location of the access points to reliably determine the position of the mobile equipment. If the location of the access points is stable, however, the location of the access point can be used to determine the location of a mobile terminal accurate to typically about 50 meters, even better if triangulation is used between multiple access points.
An example of a Wi-Fi positioning system is the Cisco Wireless Position Appliance20 that is part of the Cisco Context-Aware Mobility solution and that can be used to track assets and users.