A method for scheduling simultaneous upstream transmissions over a plurality of channels in a shared spectrum, the method comprising: identifying a region of shared spectrum allocated to at least two channels that includes both a Data Over Cable Service Interface Specification, DOCSIS, version 3.1 based on orthogonal frequency division multiple access, OFDMA, channel and at least one additional channel for legacy DOCSIS version 3.0 based on single-carrier quadrature amplitude modulation, SC-QAM; designating a bucket (601, 602) of time-and-frequency-division allocation units, TAUs, for said region of shared spectrum, wherein said TAUs are used to divide the spectral resources in that region and the bucket represents the total number of TAUs available for that region; distributing the total number of available TAUs in said bucket into at least two buckets (606, 608) corresponding to the at least two channels according to a configured initial setting; for each of the at least two channels, using the TAUs available in the corresponding bucket (606, 608) for scheduling traffic (610, 612), wherein traffic to be scheduled for each channel is queued in an independently maintained queue (609, 611) corresponding to that channel; examining utilization of the distributed TAUs (606, 608) by the at least two channels and/or the bandwidth demands of the queues (609, 611) associated to the schedulers (610, 612) of the at least two channels; adjusting the initial setting according to the outcome of said examining so as to update the distribution of a subsequent bucket of TAUs; and wherein allocation times of the channel for DOCSIS version 3.1 based on OFDMA start and end on OFDMA frame boundaries. identifying a region of shared spectrum allocated to at least two channels that includes both a Data Over Cable Service Interface Specification, DOCSIS, version 3.1 based on orthogonal frequency division multiple access, OFDMA, channel and at least one additional channel for legacy DOCSIS version 3.0 based on single-carrier quadrature amplitude modulation, SC-QAM; designating a bucket (601, 602) of time-and-frequency-division allocation units, TAUs, for said region of shared spectrum, wherein said TAUs are used to divide the spectral resources in that region and the bucket represents the total number of TAUs available for that region; distributing the total number of available TAUs in said bucket into at least two buckets (606, 608) corresponding to the at least two channels according to a configured initial setting; for each of the at least two channels, using the TAUs available in the corresponding bucket (606, 608) for scheduling traffic (610, 612), wherein traffic to be scheduled for each channel is queued in an independently maintained queue (609, 611) corresponding to that channel; examining utilization of the distributed TAUs (606, 608) by the at least two channels and/or the bandwidth demands of the queues (609, 611) associated to the schedulers (610, 612) of the at least two channels; adjusting the initial setting according to the outcome of said examining so as to update the distribution of a subsequent bucket of TAUs; and wherein allocation times of the channel for DOCSIS version 3.1 based on OFDMA start and end on OFDMA frame boundaries.