An Inertial navigation System (INS) is self-contained,immune to jamming/interference and in many other ways is ideally for pedestrian navigation applications especially in indoor environments.However,due to the sensor properties the quality of the navigation solution from a stand-alone INS will degrade rapidly,and must rely on some form of external correction/calibration/aiding to ensure system stability and reliability.In this contribution the authors use GPS when outdoors and WiFi when indoors to aid the INS in order to support seamless pedestrian navigation.To improve the performance of WiFi positioning,an enhanced fingerprinting method is proposed.A new fingerprinting database augmented by two types of map-based information is described.One is the topological relationship linking corridors,and the other is the orientation information of different corridors.Test results confirm that the navigation accuracy and stability is improved.