Integrity is one of the four basic parameters (accuracy, continuity and availability as the other three) which are used to assess the performance of satellite navigation systems. This paper introduces the basic concept of integrity and analyses the factors which affect the integrity of GPS. Focusing on the three main components of GPS and in terms of the object to which integrity monitoring aims, the paper puts forward a new classification of the technology. The paper classifies the technology into three categories, namely RAIM (Receiver Autonomous Integrity Monitoring), GIC (GPS Integrity Channel) and SAIM (Satellite Autonomous Integrity Monitoring) and studies several typical methods of integrity monitoring.
