TABLE OF CONTENTS This chapter describes how location is determined its, measurements, and their role in ascertaining location. A new network entity, the Access Location Entity (ALE), is defined to provide location measurements, and the Flexible LIS-ALE Protocol (FLAP) used for communication between the LIS and ALE is introduced.
This section provides background information necessary for the chapters that follow, which describe how location determination works within particular types of access networks.
A location measurement is a datum that can be used to locate a device. A LIS uses measurements to determine location, and a location measurement can be used as a key into a location database, or as input to an algorithm.
A location measurement is a piece of data about a network that does not necessarily contain actual location information. Measurements of this sort hold no specific information about the network, thus the devices that provide location measurements do not need to know about location, only about the network characteristics that are important to their operation.
For instance, a wireless base station might report the strength of the radio signal it receives, or timing information or a wired switch reports the port that traffic is routed to. Specific examples of measurements are shown in detail in Chapters 5, 6, and 7.
A centralized LIS provides a number of benefits, particularly for data management and client access, but its position in the network makes it unsuitable for acquiring network measurements. The Access Location Entity (ALE),...
