A method for dynamic bandwidth allocation (DBA) in a passive optical network (PON) comprises the steps of: in a configuration stage, dividing a predetermined grant cycle into N parts, dividing by an optical line terminal (OLT) a plurality of optical network units (ONUs) into N ONU groups and in each cycle part, concurrently allocating grants to ONUs of one ONU group while having the ONUs of at least one other ONU group send reports and data to the OLT. In a preferred embodiment, the cycle is divided into two fixed half cycles.