ments. As the beams are spatially oriented, just a few of these, if at all any, will be received by the UE. This also depends on the beamwidth with which the initial access beam is transmitted, and in practice this may be wider than the actual data (PDSCH) beam as the signal needs to reach the UE in order for the UE to get connected to the transmission point and hence to the network. For the initial beam acquisition, it is likely that also the UE would utilize a wider beam and for data reception. It is worth noting that the beamwidth is not something which is written in the specification, the gNB and UE being free to utilize whatever beam width they see fit. However, as initial access is a very important procedure, it is likely that the beamwidth used in this situation is wider than the ones used for data transmission of the PDSCH and PUSCH. 6.12.2.2 Beam Measurement and Reporting Beam measurement and reporting consist of acquiring the beam information for data transmission. While initial beam acquisition may be done on a wider initial access beam containing the SS Block, this beam can be further refined (narrowed) for data transmission. How- ever, the same beam width may be used for data transmission as it has been used for initial access transmission. In Figure 6.35, we depict an example of such beam refine- ment. The wide beam of initial access is further narrowed when transmitting CSI-RS. The transmission of CSI-RS is necessary as all the CSI components, such as the PMI, sweeping Figure 6.34 Sweeping beams at gNB sweeping and UE. 6.12 5G MIMO and Beamforming Operation Figure 6.35 Beam refinement. SSB wide beam CSI-RS narrow beam rank, and CQI, are measured on this reference signal. In addition, the so-called TRS (tracking reference signal) is also transmitted via such beams. The TRS is needed for establishing fine time and frequency synchronization at the UE. In some sense, the func- tionality of LTE CRS has been now split into TRS and CSI-RS, this decoupling bringing more flexibility to the system. The measu