A method is disclosed to receive a signal, in a receiver from a transmitter (e.g., over a period of time). The signal propagates from the transmitter to the receiver in a direction of propagation. The receiver may move in a direction of motion relative to the transmitter. The signal includes a cyclic feature. The method may determine a change rate of a Doppler shift of the cyclic feature in the received signal. The method may determine, based on the change rate of the Doppler shift of the cyclic feature, an angle between the direction of motion of the receiver and the direction of propagation, the range between the receiver and the transmitter, and/or the locations of the transmitter and/or receiver.

A method is disclosed to receive a signal, in a receiver from a transmitter (e.g., over a period of time). The signal propagates from the transmitter to the receiver in a direction of propagation. The receiver may move in a direction of motion relative to the transmitter. The signal includes a cyclic feature. The method may determine a change rate of a Doppler shift of the cyclic feature in the received signal. The method may determine, based on the change rate of the Doppler shift of the cyclic feature, an angle between the direction of motion of the receiver and the direction of propagation, the range between the receiver and the transmitter, and/or the locations of the transmitter and/or receiver.

Mechanisms for selecting beam direction for a radio communications device are provided. A method is performed by the radio communications device. The method includes obtaining radio channel estimates of a radio channel on which radio waves have been transmitted between the radio communications device and another radio communications device at an angle of arrival and departure. The method includes determining a Doppler shift from the radio channel estimates. The method includes estimating at least one of the angle of arrival and departure of the radio waves based on the Doppler shift. The method includes selecting a beam direction for a signal to be transmitted between the radio communications device and this another radio communications device over the radio channel according to the estimated angle of arrival or departure.

Mechanisms for selecting beam direction for a radio communications device are provided. A method is performed by the radio communications device. The method includes obtaining radio channel estimates of a radio channel on which radio waves have been transmitted between the radio communications device and another radio communications device at an angle of arrival and departure. The method includes determining a Doppler shift from the radio channel estimates. The method includes estimating at least one of the angle of arrival and departure of the radio waves based on the Doppler shift. The method includes selecting a beam direction for a signal to be transmitted between the radio communications device and this another radio communications device over the radio channel according to the estimated angle of arrival or departure.

A method for determining a spatial orientation of a body, including receiving, by receiving equipment located with the body, at least three electromagnetic signal sets, each of the received signal sets having been transmitted by a different one of at least three separate transmitters at different locations, detecting, for each one of the received signal sets, information that partially defines a direction from the body to the transmitter from which the signal set was received, the detected information including one of two angles that fully define an arrival direction from which the body received the signal set in relation to a body frame, the detected information not including a second of the two angles, and determining the spatial orientation of the body, including yaw, pitch, and roll angles relative to a navigation frame, using the detected information for each one of the received signal sets.

A method performed by a first communication device operating in a wireless communications network. The first communication device obtains a set of correspondences associating: i) each set (ω.sub.i) of a plurality of sets of antenna weights (ω.sub.1 . . . ω.sub.i) having been sent by a third communication device in response to having received a respective set (RSs.sub.i) of a plurality of sets of radio signals (RSs.sub.1 . . . RSs.sub.i) from a set of antenna ports in a second communication device, with ii) a respective direction of transmission (d.sub.i) between the second communication device and the third communication device. The respective direction is relative to an orientation (α.sub.i) of the second communication device. The respective direction of transmission (d.sub.i) is a selected direction of transmission (d.sub.i,αi). The first communication device then initiates transmission of a new radio signal, based on the obtained set of correspondences.

A method performed by a first communication device operating in a wireless communications network. The first communication device obtains a set of correspondences associating: i) each set (ω.sub.i) of a plurality of sets of antenna weights (ω.sub.1 . . . ω.sub.i) having been sent by a third communication device in response to having received a respective set (RSs.sub.i) of a plurality of sets of radio signals (RSs.sub.1 . . . RSs.sub.i) from a set of antenna ports in a second communication device, with ii) a respective direction of transmission (d.sub.i) between the second communication device and the third communication device. The respective direction is relative to an orientation (α.sub.i) of the second communication device. The respective direction of transmission (d.sub.i) is a selected direction of transmission (d.sub.i,αi). The first communication device then initiates transmission of a new radio signal, based on the obtained set of correspondences.

Mechanisms for selecting beam direction for a radio communications device are provided. A method is performed by the radio communications device. The method includes obtaining radio channel estimates of a radio channel on which radio waves have been transmitted between the radio communications device and another radio communications device at an angle of arrival and departure. The method includes determining a Doppler shift from the radio channel estimates. The method includes estimating at least one of the angle of arrival and departure of the radio waves based on the Doppler shift. The method includes selecting a beam direction for a signal to be transmitted between the radio communications device and this another radio communications device over the radio channel according to the estimated angle of arrival or departure.

Mechanisms for selecting beam direction for a radio communications device are provided. A method is performed by the radio communications device. The method includes obtaining radio channel estimates of a radio channel on which radio waves have been transmitted between the radio communications device and another radio communications device at an angle of arrival and departure. The method includes determining a Doppler shift from the radio channel estimates. The method includes estimating at least one of the angle of arrival and departure of the radio waves based on the Doppler shift. The method includes selecting a beam direction for a signal to be transmitted between the radio communications device and this another radio communications device over the radio channel according to the estimated angle of arrival or departure.

Multiple radio transmissions are processed to determine, for each of a number of directions of arrival of the radio transmissions, a most direct direction of arrival, for example, to distinguish a direct path from a reflected path from the target. In some examples, the radio transmissions include multiple frequency components, and channel characteristics at different frequencies are compared to determine the direct path.