Complete single-channel solutions to hidden terminal problems in wireless LANs

Abstract

We specify and analyze two variants of floor acquisition multiple access protocols for CSMA single-channel wireless LANs (WLANs) with hidden terminals. One variant assumes that all stations have the same functionality, and the other assumes base station control. These are the first protocols that solve the hidden-terminal problems of single-channel WLANS. Stations use carrier sensing and a three way handshake, just as advocated in MACA, IEEE 802.11 and FAMA-NTR introduced in the past. However, the clear to send (CTS) from a receiver lasts long enough to be able to jam any hidden sender that did not hear the request to send (RTS) being acknowledged and who started sending its RTS after the receiver started sending the CTS. We verify that this jamming of the "offending senders" by the receivers permits floor acquisition to be enforced correctly, i.e., that no data packet sent by a sender will ever collide at the intended receiver with any packet sent by any other station hidden or exposed from the sender. The performance of these protocols is compared by simulation with the performance of MACAW reported in the past.