A wireless communications system for categorized channel reservation is provided with a first wireless communications module and a second wireless communications module. The first wireless communications module transmits or receives a plurality of first wireless signals. The second wireless communications module transmits a first control packet according to an activity schedule of the first wireless communications module to disable a plurality of wireless communications stations from data transmissions, and transmit a second control packet to enable a predetermined number of the wireless communications stations to perform the data transmissions.