According to some embodiments, a method for use in a user equipment (UE) of managing a listen-before-talk (LBT) contention window size comprises transmitting a first burst of uplink subframes after a first LBT procedure performed using an LBT contention window size, and determining a reference subframe based on the first burst. The reference subframe is associated with a reference hybrid automatic repeat request (HARQ) process identifier. The method further comprises receiving scheduling for a second burst of uplink subframes. The scheduling comprises an associated HARQ process identifier and an associated new data indicator (NDI) for each subframe. When the UE determines the HARQ process identifier associated with at least one of the subframes of the second burst matches the reference HARQ process identifier, then if the associated NDI indicates new data, the method resets the LBT contention window size, else the method increments the LBT contention window size.