CTS-to-self as a protection mechanism for the no acknowledgment protocol in VoIP WLANs

Abstract

In modern WLANs, the No Acknowledgment (NoACK) policy implements an acknowledgment-free protocol that is able to boost Medium Access Control (MAC) layer performance. However, due to the lack of a MAC-level recovery, a protection mechanism must be used in conjunction with the NoACK protocol in order to minimize the probability of packet loss. There are mainly two protection mechanisms defined by the IEEE 802.11 standard, namely RTS/CTS and CTS-to-self. While the first is well studied when used to protect the frame exchange with NoACK, the latter has not received any attention as a NoACK protection mechanism. In this paper we provide an analytical study to determine the system efficiency in terms of achieved throughput when these mechanisms are used to protect the acknowledgment suppression protocol in WLANs supporting voice applications. Based on the findings presented, a scheme based on the CTS-to-self mechanism is proposed to aid the application of the NoACK policy in WLANs. The proposed scheme is evaluated and its effectiveness is proven by means of simulation.