A method for accessing a wireless channel by a device (112, 113) that intends to transmit data, wherein access to channel is controlled by a wireless channel controller (111), the method comprising: registering the device (112, 113) at the wireless channel controller (111) as an authorized device; synchronizing (201) a timer of the device (112, 113) indicating time windows; determining (202) a designated time window during which the device (112, 113) can transmit data; performing (203) a clear channel assessment procedure during the preceding time window such that the clear channel assessment ends at the end of the time window preceding the designated time window; and beginning transmission (204) of data at the beginning of the designated time window.