Towards a Full-Duplex MAC protocol efficiently handling the imbalance between the lengths of data streams in High-Efficiency WLANs

The technique of Full-Duplex is a promising technology for IEEE 802.11ax next generation of high-density wireless networks. It allows to send and receive data frames simultaneously on the same radio frequencies by using specific radio antennas named SIC (Self-Interference Cancellation). However, the imbalance between the lengths of Down-Link (DL) and Up-Link (UL) data streams impedes an effective use of this transmission technique, since an empty time interval is known as Opportunity Window (OW) is generated at the end of UL data stream and it lasts until the end of DL transmission. The aim of this paper is to extend the operation rules of the In-Frame Querying protocol, in order to bring modifications to fully take advantage of the Full-Duplex radio communications. The basic principle of the extended Full-Duplex MAC protocol is finding the candidate stations that will use the opportunity window with a minimum of overhead through a deterministic method. The simulation results show that the new version of In-Frame Querying protocol provides better performance, especially when the network is dense or the traffic from the access point is heavy.