Effectiveness of RTS/CTS Handshake in IEEE 802.11a Wireless LANs

Introduction: IEEE 802.11 Distributed Co-ordination Function (DCF) employs two techniques for packet transmission: the basic access and the RTS=CTS scheme [1]. The optional four-way handshaking RTS=CTS scheme involves the transmission of short requestto -send (RTS) and clear-to-send (CTS) control packets prior to the data packet transmission in order to shorten the collision duration. Although the RTS=CTS scheme is also employed to improve performance in the presence of hidden stations, the authors in [2] have reported several potential problems in the ability of the RTS=CTS scheme to address the hidden station problem and reduce interference. Bianchi in [3] developed a mathematical model for 802.11 DCF when no hidden stations are present and showed that RTS=CTS is effective in reducing collision duration for the 1 Mbit=s data rate. However, in [3] the difference between control rate and data rate has not been investigated and therefore the conclusions on the RTS=CTS effectiveness sh

Resonant transmission line method for unconventional fibers

We provide a very general review of the resonant transmission line method for optical fiber problems. The method has been found to work seamlessly for a variety of difficult problems including elliptical and eccentric core fibers as well as "holey" photonic crystal fibers. This new version has been shown to offer great versatility with respect to cases of unconventional, inhomogeneous index profiles. © 2019 by the authors