A wireless communication device is configured to perform clear channel assessment (CCA) using one or more CCA levels that are selected based on various criteria. The device receives or detects one or more packets on the communication medium, and the device then processes those one or more packets to determine status of one or more channels within one or more frequency bands using the one or more CCA levels. These CCA levels may be selected based on one or more parameters, and different CCA levels may be used at different times, for different channels, etc. Also, different CCA levels may be used to determine the status of different channels, different portions of the frequency spectrum, etc. When at least one channel is determined as being clear and available for usage, the device is configured to support communications with one or more other devices via one or more channels.