a method for dynamic bandwidth allocation in a passive optical network comprises the steps of : in a configuration stage , dividing a predetermined grant cycle into n parts , dividing by an optical line terminal a plurality of optical network units 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 .