<P> Control frames facilitate in the exchange of data frames between stations . Some common 802.11 control frames include: </P> <Ul> <Li> Acknowledgement (ACK) frame: After receiving a data frame, the receiving station will send an ACK frame to the sending station if no errors are found . If the sending station doesn't receive an ACK frame within a predetermined period of time, the sending station will resend the frame . </Li> <Li> Request to Send (RTS) frame: The RTS and CTS frames provide an optional collision reduction scheme for access points with hidden stations . A station sends a RTS frame as the first step in a two - way handshake required before sending data frames . </Li> <Li> Clear to Send (CTS) frame: A station responds to an RTS frame with a CTS frame . It provides clearance for the requesting station to send a data frame . The CTS provides collision control management by including a time value for which all other stations are to hold off transmission while the requesting station transmits . </Li> </Ul> <Li> Acknowledgement (ACK) frame: After receiving a data frame, the receiving station will send an ACK frame to the sending station if no errors are found . If the sending station doesn't receive an ACK frame within a predetermined period of time, the sending station will resend the frame . </Li> <Li> Request to Send (RTS) frame: The RTS and CTS frames provide an optional collision reduction scheme for access points with hidden stations . A station sends a RTS frame as the first step in a two - way handshake required before sending data frames . </Li>

802.11 ac is the current wireless ethernet standard