An approach is described for a wireless device comprising a transceiver and a processor communicatively coupled to the transceiver. The processor is configured to detect a packet for transmission; scan, using the transceiver, a channel during an initial sliding window, the initial sliding window having N symbol durations; determine a power distribution of the initial sliding window based on the channel scan; determine that the channel is occupied during a first time period of the initial sliding window based at least on the power distribution; and determine a second sliding window having a second time period and a third time period. The second time period overlaps with the initial sliding window and a length of the third time period is determined based at least on the power distribution. The processor is further configured to scan, using the transceiver, the channel during the third time period; determine that the channel is idle during the third time period of the second sliding window; and transmit, using the transceiver, the packet to a second wireless device on the channel responsive to the third time period being idle.