Читать книгу Position, Navigation, and Timing Technologies in the 21st Century - Группа авторов - Страница 51

Triangulation is a family of wireless radio‐signal‐based methods that use the geometric properties of triangles to determine location. The methods can be broadly classified as angulation‐based and lateration‐based [27]. Angulation locates an object by computing its angles relative to multiple fixed reference points. In contrast, lateration estimates the position of an object by measuring its distances from multiple reference points (the general term multilateration is often used whenever two or more reference points are used). As a proxy for directly using distance, some methods use the RSS, ToA or time difference of arrival (TDoA). In these methods, the distance is derived by computing the attenuation of the signal strength or by multiplying the radio signal velocity and the signal travel time. A few methods also use the round‐trip time of flight (RToF) or received signal phase for distance estimation. We describe the major triangulation‐based methods for indoor localization in the rest of this section.