y the MMSE (Minimum Mean Square Error) equalization method or by the ZF (Zero Forcing) equalization method. 5G-NR Radio Interface - MIMO and Beamforming 6.1.2. Baseband beamforming Beamforming is a complementary mechanism to MIMO. Beamforming uses multiple antennas to control the direction of the beam by individually weighting the amplitude and phase of each transmitted signal, by applying a specific precoding matrix to each component of the transmitted signal (Figure 6.3) in baseband. The precoding vector is determined by the mobile from the reference signals and transmitted to the base station. Beamforming logically reduces the beam opening angle and limits the level of interference between cells. The beamforming allows us to increase the range thanks to the increase in power as a result of the contribution of each transmitted signal. Received signals are dephased Signal S Precoding Results Received signals are in phase Figure 6.3. Beamforming 6.1.3. Active antennas and massive-MIMO Elevation Beamforming (EBF) allows a beam to be directed in a specific way, for example, a beam pointing either up or down. This technique contrasts with conventional antenna systems for which the tilt angle is fixed. The Active Antenna System (AAS) mechanism is based on the formation of elevation beams. The horizontal and vertical directions can be combined, leading to two-dimensional beam formation (Figure 6.4). NG-RAN and 5G-NR Beamforming in the Beamforming in the vertical plane horizontal plane Figure 6.4. Beamforming in horizontal and vertical planes (source: NTT Docomo Technical Journal Vol. 18, No. 2) This new beamforming technique tends to increase the number of antennas as the signal has spatial access to more degrees of freedom. The active antenna system (AAS) consists of a block of TXU transmitters and TRU receivers, an RDN (Radio Distribution Network) and an AA (Antenna Array) network (Figure 6.5). Transmitter Cross-polar Receiver network TXU / TRU Radio TXU / TRU Distribution Network TXU / TRU Figure 6.5. Active antenn