System and method for performing clear channel assessment for simultaneous transmission in a device implementing multiple wireless protocols. The system may include first and second wireless protocol circuitry configured to generate first and second signals, respectively, for wireless transmission according to first and second wireless protocols, respectively. A first in-band signal strength threshold and a second in-band signal strength threshold may be maintained by the first wireless protocol circuitry. It may be determined whether the first or second in-band signal strength threshold should be used in performing the clear channel assessment. Clear channel assessment may be performed using the determined in-band signal strength threshold. Performing clear channel assessment may include comparing an ambient signal strength on a channel with the determined in-band signal strength threshold. The first wireless protocol circuitry may be configured to determine whether to wirelessly transmit first signals based on the clear channel assessment.