A method includes receiving a data fragment of a block of data fragments of a single data unit from a wireless device at a receiver. The method includes, in response to determining that the data fragment is a last data fragment of the block of data fragments, transmitting an acknowledgement to the wireless device. The acknowledgement indicates whether each data fragment of the block of data fragments was received from the wireless device. The method includes, in response to determining that the data fragment is a last data fragment of the single data unit, transmitting the acknowledgment to the wireless device. The method further includes, in response to determining that the data fragment is not the last data fragment of the block of data fragments or the last data fragment of the single data unit, refraining from transmitting the acknowledgement to the wireless device.