A wireless access point device receives a packet including a first source port number from a source wireless terminal device, determines if the packet is a control packet according to the first source port number, and obtains a time interval and a second source port number from the control packet and to receive a new packet. The wireless access point device further determines if the new packet is the data packet according to whether the first source port number of the new packet is the same as the second source port number, starts a timer to time for the time interval once the new packet is the data packet, and transmits a Clear-to-Sent packet to other wireless terminal devices once the timer times out.