A wireless communications system includes an access point (AP) and at least a station. The AP transmits a periodic scheduling indicator, a compression indicator and scheduling information to a station. The periodic scheduling indicator indicates whether a periodic transmission is scheduled for a station, and wherein the compression indicator indicates whether the scheduling information for the station is compressed scheduling information. The station determines full scheduling information in accordance with the periodic scheduling indicator, the compression indicator and the scheduling information. Then, the station transmits a packet in accordance with the full scheduling information to the AP. Reduction in signaling overhead is achieved.