Systems, methods, and instrumentalities are disclosed for multi-resolution training, for example, in millimeter wave (mmW) WLAN systems. In a Multi-Resolution Beam Refinement Protocol (MR-BRP), an access point (AP)/PBSS control point (PCP) and a station (STA) may perform multi-resolution beamforming training, for example, by changing a sub-beam resolution or by maintaining sub-beam resolution while changing a resolution of the beamforming training between levels or stages of training. Sub-beam resolution may be changed, for example, by assigning different angular spreads to or by downselecting a number of antenna elements while keeping inter-element spacing constant between levels of training. Resolution of beamforming training may be changed, for example, by downsampling sub-beams or by downsampling antenna elements while adjusting inter-element spacing. Beamforming training (e.g. refinement) levels may refine beams by changing a resolution of antenna weight vectors (AWVs). An AP/PCP and STA may search through a sector multiple times with sub-beams of different resolution to identify a correct pair of sub-beams at a desired resolution. MR-BRP may be used for single or multiple beams, for example, to generate M sub-beams (AWVs) for N beams sequentially or in parallel. MR-BRP may be used for beam tracking. Devices may save the best sub-beam at each level of MR-BRP and may revert (fall back) to a sub-beam at previous level. MR-BRP signaling may indicate MR-BRP capability, type, frame format, etc.