General principles of beam management are in mmwave are as follow :
P1: Beam Establishment (initial gNB beam acquisition)
Beam sweeping is used to cover a given area (e.g. 120° span)
- On gNB side wide beam sweeping is used, UE detects best beam
- In this procedure wide beams are used both on gNB and UE sides
 P2: gNB beam refinement & tracking (gNB Tx)
- gNB refines beam (e.g, sweeping narrower beams within a wide beam)
- Â UE switch from wide to narrow beam or change of narrow beam
 P3: UE beam refinement & tracking (UE Rx)
- gNB fixes a beam, UE measures currently used gNB beam and selects a narrower receiver beam
- Wide beam can be used as initial access and fall-back in case of loss of narrow beam
