Methods and apparatuses are disclosed for a network controller to receive data from a user terminal (UT) via a satellite in a satellite system. The network controller may allocate contention-based resources of the satellite system to a plurality of UTs, and may activate the allocated contention-based resources by transmitting an activation signal to the plurality of UTs. The network controller may receive, from a first UT via a satellite of the satellite system, a first portion of data on a plurality of subframes of the contention-based resources during a time period, and may suspend the allocation of contention-based resources after an expiration of the time period or upon a grant of scheduled return link resources to the first UT, irrespective of collisions on the contention-based resources.