Baseband unit, radio unit and methods in a wireless communications networks

A method performed by a Radio Unit, RU, (112) for performing beamforming for a communication between a User Equipment, UE, (120) and a base station (110) in a wireless communications network (100) adapted to use a multiple antenna system for communication, wherein the RU (112) is associated with the base station (110), the method comprising:

• receiving (401) from a Base Band Unit, BBU, (111) associated with the base station (110), via a fronthaul interface, a subset of channel taps selected by the BBU (111) from a larger set of channel taps to reduce required fronthaul capacity, and information identifying the selected subset of channel taps to enable reconstruction of the channel taps in the tap domain;
• reconstructing (402) the channel taps in the tap domain by using the information identifying the selected subset of channel taps to determine positions of the selected channel taps within a complete set of channel taps;
• transforming (403) by a mathematical transformation comprising an inverse discrete Fourier transform (IDFT) or inverse discrete cosine transform (IDCT), at least some of the channel taps out of the set of channel taps, to obtain corresponding frequency domain channel values related to respective subcarriers out of a number of subcarriers;
• determining (404) respective Beamforming Weights, BFWs, according to the obtained frequency domain channel values, on the respective subcarriers out of the number of subcarriers;
• and
• performing (405) beamforming with the determined BFWs on the respective subcarriers out of the number of subcarriers for the communication between the UE (120) and the base station (110).