Embodiments of the present invention provides a system and method of a smart door. The system includes a camera, a display interface, and an internal rechargeable battery. In some embodiments, a camera and a display interface are mounted on both sides of the door, thus allowing users to communicate through the door while the door forms a physical barrier between the communicating users. The system networks multiple doors together. At least one door can track occupants location and entrance/exit within a structure. The system also provides the capability to give user wellness information and operate fully with biometrics

A method and system are provided for improved pedestrian dead reckoning. In an embodiment, the crab angle of a device, i.e., the angle by which the device direction of travel differs from the device orientation, is determined via the processing of measurements from a vector accelerometer. The measured acceleration vector is rotated so that one component is vertical, and the crab angle is then found by determining a horizontal direction having the greatest energy. Correlations between the two horizontal acceleration components and the vertical acceleration component may be computed to determine the user's gait, further improving dead reckoning, e.g., for improving indoor position resolution.