Abstract: A method of calibrating a magnetometer may include; obtaining at least four measurement values using the magnetometer, calculating a center and a radius of a sphere in accordance with the measurement values, wherein the center and the radius of the sphere correspond to an internal magnetic field associated with an electronic device including the magnetometer, and calibrating an output of the magnetometer in accordance with the center of the sphere.

Abstract: A system to recognize user activity includes a filter to form a gravity measurement from a three-dimensional (3D) accelerometer measurement of a user activity; a body component extractor to form a body measurement of the user activity by removing the gravity measurement from the 3D accelerometer measurement; a rotation matrix calculator to form a rotation matrix that is used to rotate the extracted gravity to align with a predetermined direction, and to rotate the 3D accelerometer measurements and the body measurement to be the input to features determiner module; and a features determiner to determine values of a predetermined number of features of the user activity based on the rotated 3D accelerometer measurement and the rotated body measurement in which the predetermined number of features are invariant under arbitrary rotation of the accelerometer measurement around the predetermined direction.

Abstract: A system to recognize user activity includes a filter to form a gravity measurement from a three-dimensional (3D) accelerometer measurement of a user activity; a body component extractor to form a body measurement of the user activity by removing the gravity measurement from the 3D accelerometer measurement; a rotation matrix calculator to form a rotation matrix that is used to rotate the extracted gravity to align with a predetermined direction, and to rotate the 3D accelerometer measurements and the body measurement to be the input to features determiner module; and a features determiner to determine values of a predetermined number of features of the user activity based on the rotated 3D accelerometer measurement and the rotated body measurement in which the predetermined number of features are invariant under arbitrary rotation of the accelerometer measurement around the predetermined direction.

Abstract: A receiver apparatus, a receiver method, a transmitter apparatus, a transmitter method, and a chipset for estimating a position of a terminal in a communication system are provided. The receiver apparatus includes a receiver configured to receive signals transmitted from two or more antennas which are in an Access Point (AP) and have radial directions which are different from each other; and a controller configured to determine signal levels with respect to the respective two or more antennas from signal strength values of signals which are distinguished by the received radial directions which are different from each other, estimate a direction and distance between the AP and the terminal on the basis of the determined signal levels, and determine the position of the terminal from the estimated direction and distance.

Abstract: A proximity estimation method and apparatus are provided for measuring a distance between devices in a wireless communication system. The method includes transmitting, by a first device, a first signal to a second device; receiving, by the first device, a second signal from the second device, in response to the first signal; and measuring, by the first device, a distance between the first device and the second device, based on a phase difference between the first signal and the second signal.