According to some embodiments, a method for use in a user equipment (UE) of managing a listen-before-talk (LBT) contention window size comprises receiving scheduling for a current burst of contiguous uplink subframes. For each subframe the scheduling comprises an associated hybrid automatic repeat request (HARQ) process identifier and a new data indicator (NDI). The method determines a reference subframe based on a previously-scheduled burst of contiguous uplink subframes. The reference subframe is associated with a reference HARQ process identifier. When the UE determines the HARQ process identifier associated with a subframe of the current scheduled burst of contiguous uplink subframes matches the reference HARQ process identifier and the NDI indicates new data, the method resets the LBT contention window. When the reference HARQ process identifier matches, but the associated NDI indicates a retransmission, or the HARQ process identifier does not match, the method increments the LBT contention window.