Deloitte Telecom SIG: Word of the Day: Location Technologies (Angle of Arrival)

Location Technologies (Angle of Arrival): Known as AOA, Angle of Arrival technology measures the direction of arrival of the caller’s signal (generally at least three measurements are needed) at different cell sites. Each cell site receiver sends this direction information to the mobile switch where the angles are compared and the latitude and longitude of the caller is computed and sent to the Public Safety Answering Point (PSAP).

PSAP: Public Safety Access Points are customarily segmented as “primary”, “secondary”, and so on. The primary PSAP is the first contact a 911 caller will get. Here, the PSAP operator verifies or obtains the caller’s whereabouts (called locational information), determines the nature of the emergency and decides which emergency response teams should be notified. Automatic Location Information (ALI) contained in a database, provides supplemental information for purposes of locating the caller, determining if hazardous materials are located at the subject, and so on. In some instances, the primary PSAP may dispatch aid. In most cases, the caller is then conference or transferred to a secondary PSAP from which help will be dispatched. Secondary PSAPs might be located at fire dispatch areas, municipal police force headquarters or ambulance dispatch centers. Often the primary PSAP will answer for an entire region.