m = 1, the UE may report the optimal TX beam index without the associated beam quality as a recommendation to the gNB for downlink beamforming. If Nbeam > 1, the UE can report the indices of Nbeam selected TX beams, for example, the best Nbeam beams, along with their measured relative/absolute qualities to the gNB. The gNB compares the quali- ties of the reported TX beams and selects one TX beam for downlink transmission. The NR also supports lower complexity beam management procedures that do not require explicit indi- cation of the selected TX beam to the UE. If the UE only reports the best TX beam index and 514 Chapter 4 only a single gNB TX-RX beam pair is used for transmission of both data and control, there is no need for explicit beam indication. In that case, the UE identifies the optimal RX beam for a given measurement, and the gNB uses the TX beam recommended by the UE for the subse- quent data and control transmissions. To receive the data and control transmissions, the UE uses the RX beam that it identified in the previous measurement. The beam quality metrics that can be used for beam measurement are for example RSRP, RSRQ, and SINR calculated based on CSI-RS. Different metrics result in different UE complexity and may be suitable different scenarios, for example, the RSRP measurement is relatively simple and more power efficient and allows fast measurement of a large number of beams, which is useful for initial beam acquisition. The CSI measurement is more complex but offers more accurate beam information, which can be used for beam refinement within a small group of candidate beams [57]. Following the initial access and connection set up, the device can assume that network transmissions to the device will use the same transmit beam that was used for SS block acquisition. Therefore, the device can assume that the receive beam which was used to acquire the SS block will also be a suitable beam for the reception of subsequent downlink transmissions. Similarly, subsequent uplink transmissions would use