Method and transmitter of a wireless communication network for analog beamforming

A transmitter operable in a wireless communication network configured for analog beamforming, the transmitter comprising a plurality of antenna branches, each antenna branch comprising an antenna element, the transmitter comprising a processing circuitry and a memory, said memory containing instructions executable by said processing circuitry, whereby the transmitter is operative for, for each antenna branch:

• obtaining a first and a second signal of an analog radio signal, the first and the second signal being split from the analog radio signal and the analog radio signal being the same at each of the antenna branches;
• obtaining information indicating a branch-specific phase-shift angle and a branch-specific amplitude determined from information identifying a radiation pattern comprising at least two directions for wireless transmission to at least one receiver;
• phase-shifting the first signal according to a first phase-shift angle and the second signal according to a second phase-shift angle, the first and the second phase-shift angle being selected so that when the first and the second signals are combined, the combined signal has the branch-specific phase-shift angle and the branch-specific amplitude indicated by the obtained information;
• obtaining information on a proportion of desired amplitude control;
• depending on the proportion of desired amplitude control, adjusting, for each antenna branch, the first phase-shift angle and the second phase-shift angle so that for full amplitude control, the first and the second phase-shift angle are maintained, and for no amplitude control, the first and the second phase-shift angles are the same as the branch-specific phase-shift angle, and for semi-amplitude control, an angular difference between the first and the second-phase shift angle are lowered;
• combining the phase-shifted first and second signals into a combined signal;
• and
• transmitting, wirelessly, the combined signal through the antenna element.

A non-transitory computer readable storage medium storing a computer program comprising instructions, which, when executed by processing circuitry of a transmitter of a wireless communication network, configured for analog beamforming, the transmitter comprising a plurality of antenna branches, each antenna branch comprising an antenna element, causes the transmitter to perform the following steps, for each antenna branch:

• obtaining a first and a second signal of an analog radio signal, the first and the second signal being split from the analog radio signal and the analog radio signal being the same at each of the antenna branches;
• obtaining information indicating a branch-specific phase-shift angle and a branch-specific amplitude determined from information identifying a radiation pattern comprising at least two directions for wireless transmission to at least one receiver;
• phase-shifting the first signal according to a first phase-shift angle and the second signal according to a second phase-shift angle, the first and the second phase-shift angle being selected so that when the first and the second signals are combined, the combined signal has the branch-specific phase-shift angle and the branch-specific amplitude indicated by the obtained information;
• obtaining information on a proportion of desired amplitude control;
• depending on the proportion of desired amplitude control, adjusting, for each antenna branch, the first phase-shift angle and the second phase-shift angle so that for full amplitude control, the first and the second phase-shift angle are maintained, and for no amplitude control, the first and the second phase-shift angles are the same as the branch-specific phase-shift angle, and for semi-amplitude control, an angular difference between the first and the second-phase shift angle are lowered;
• combining the phase-shifted first and second signals into a combined signal;
• and
• transmitting, wirelessly, the combined signal through the antenna element.