Why RTS-CTS is not your ideal wireless LAN multiple access protocol

Abstract

Although request-to-send clear-to-send (RTS-CTS) has been introduced as a uniform improvement over carrier sense multiple access (CSMA) in a wireless LAN environment, it is not. As it tries to solve the hidden-stations problem of CSMA, it creates new problems derived from the interaction among its control and data packets. We systematically identify and classify the sequences of events where CSMA and RTS-CTS depart from an ideal behavior, and we define a reference configuration and an analytical model on the basis of which a comparative study of protocol performance is made. The results show that RTS-CTS falls short of an ideal protocol, in some cases performing even worse than CSMA. This is especially noticeable in situations where the interaction between control packets in RTS-CTS prevents transmissions that under CSMA could occur concurrently and successfully.