ngs (SCs and formats are defined for PRACH, and we will examine them in detail in the next section of this chapter. For the moment, we will imagine that the subcarrier spacing used in the PRACH by the device is indicated in the RACH configuration of the RMSI, and we are not interested in the PRACH format. Note also that the beam used by the device at this point was selected by itself, based on the received SS block in the downlink. The next message, Msg 2, is sent from the gNB to the device. It uses the same numerology as the RMSI, and the beam used is derived from the beam that the device used or selected in the PRACH transmission, as we described earlier. Then, the device sends Msg 3 to the gNB, using the configured numerology in an RMSI and a device- selected beam, which will be typically the same as the Msg 1 beam. Finally, the gNB sends Msg 4 to the device using the same numerology as Msg 2. For the beam to be used in transmission, there are two options. The first one is that the previous message from the device to the gNB does not contain any beam report information; in that case, the same beam as Msg 2 is used. If Msg 3 from the device to the gNB contains beam report information, the gNB can use it to select a better beam from which to send a message. The initial access and random access procedures that we described here are part of NR beam management. Now, we are going to understand what beam management is. Beam management Beam management is responsible for maintaining a set of beams in the gNB and a device that can be used for downlink transmission and uplink reception. This consists of several aspects: Beam determination: This concept is defined by what means the gNB or the device selects its own transmission and reception beams Beam measurement: This is used to measure the characteristics of the received beam-formed signals Beam reporting: This is used by the device to report to the gNB information about the received beamforming signals, obtained through the previous beam measurement Beam sweeping: As 