Angle of arrival estimation in a radio communications network

A radio transceiver device, the radio transceiver device comprising:

• a communication interface;
• and
• processing circuitry coupled to the communication interface, the processing circuitry being configured to cause the radio transceiver device to:
• obtain measurements of a radio signal as received either sequentially or simultaneously in two receive beams, a first receive beam and a second receive beam, covering a given angular sector, the two receive beams being created by analog beamforming in one or more antenna arrays, wherein the receive beams have different beam patterns and at any angle within the given angular sector at most one of the beam patterns has gain below a threshold and further wherein the radio signal was transmitted by a transmitting radio transceiver device, wherein obtaining the measurements comprises:
• estimating a first channel for the first receive beam, thereby obtaining a first channel estimate;
• estimating a second channel for the second receive beam, thereby obtaining a second channel estimate, wherein a ratio of the first channel estimate and the second channel estimate comprises a magnitude value and a phase value;
• determining the magnitude value and the phase value of the ratio of the first channel estimate and the second channel estimate;
• use the determined magnitude and phase values and a discriminator function to estimate an angle of arrival (α) of the radio signal received at the receiving radio transceiver device;
• and
• based on the estimated angle of arrival, select from among a plurality of beams a beam for use in subsequent data communication with the transmitting radio transceiver device, wherein
• the discriminator function is based on the beam patterns and is, within the given angular sector, a one-to-one function of the angle of arrival (α), wherein
• a first function maps the magnitude value to a first angle of arrival value and a second angle of arrival value, and
• the step of using the determined magnitude and phase values to estimate the angle of arrival comprises:
• determining the angle of arrival values to which the magnitude value is mapped;
• and
• selecting, based on the phase value, one of the angle of arrival values to which the magnitude value is mapped, wherein the selected angle of arrival value is the estimated angle of arrival value.

A computer program product comprising a non-transitory computer readable medium storing a computer program, the computer program comprising computer code which, when run on processing circuitry of a radio transceiver device causes the radio transceiver device to:

• obtain measurements of a radio signal as received either sequentially or simultaneously in two receive beams, a first receive beam and a second receive beam, covering a given angular sector, the two receive beams being created by analog beamforming in one or more antenna arrays, wherein the receive beams have different beam patterns and at any angle within the given angular sector at most one of the beam patterns has gain below a threshold and further wherein the radio signal was transmitted by a transmitting radio transceiver device, wherein obtaining the measurements comprises:
• estimating a first channel for the first receive beam, thereby obtaining a first channel estimate;
• estimating a second channel for the second receive beam, thereby obtaining a second channel estimate, wherein a ratio of the first channel estimate and the second channel estimate comprises a magnitude value and a phase value;
• determining the magnitude value and the phase value of the ratio of the first channel estimate and the second channel estimate;
• use the determined magnitude and phase values and a discriminator function to estimate an angle of arrival (α) of the radio signal received at the receiving radio transceiver device;
• and
• based on the estimated angle of arrival, select from among a plurality of beams a beam for use in subsequent data communication with the transmitting radio transceiver device, wherein
• the discriminator function is based on the beam patterns and is, within the given angular sector, a one-to-one function of the angle of arrival (α), wherein
• a first function maps the magnitude value to a first angle of arrival value and a second angle of arrival value, and
• the step of using the determined magnitude and phase values to estimate the angle of arrival comprises:
• determining the angle of arrival values to which the magnitude value is mapped;
• and
• selecting, based on the phase value, one of the angle of arrival values to which the magnitude value is mapped, wherein the selected angle of arrival value is the estimated angle of arrival value.

A method for estimating angle of arrival (α) of a radio signal in a radio communications network, the method being performed by a receiving radio transceiver device, the method comprising:

• obtaining measurements of the radio signal as received either sequentially or simultaneously in two receive beams covering a given angular sector, the two receive beams being created by analog beamforming in one or more antenna arrays each having a plurality of antenna elements, wherein the receive beams have different beam patterns and at any angle within the given angular sector at most one of the beam patterns has a gain below a threshold and further wherein the radio signal was transmitted by a transmitting radio transceiver device;
• determining a magnitude value and a phase value based on the obtained measurements;
• using the determined magnitude and phase values to estimate the angle of arrival (α);
• and
• based on the estimated angle of arrival, selecting from among a plurality of beams a beam to use in subsequent data communication with the transmitting radio transceiver device, wherein
• a first function maps the magnitude value to a first angle of arrival value and a second angle of arrival value, and
• the step of using the determined magnitude and phase values to estimate the angle of arrival comprises:
• determining the angle of arrival values to which the magnitude value is mapped;
• and
• selecting, based on the phase value, one of the angle of arrival values to which the magnitude value is mapped, wherein the selected angle of arrival value is the estimated angle of arrival value.