  Ever since the feasibility of in-band full-duplex (FD) at the Physical (PHY)
layer has been established, several studies have emerged investigating protocol
aspects of enabling FD operation in various legacy wireless technologies.
Recently, the adoption of a simultaneous transmit and receive (STR) mode for
next generation wireless local area networks (WLANs) has received significant
attention. Enabling STR mode (FD communication mode) in 802.11 WLANs creates
bi-directional FD (BFD) and uni-directional FD (UFD) links. STR mode in 802.11
WLANs must be enabled with minimal protocol modifications while accounting for
the co-existence and compatibility with legacy nodes and protocols. This paper
provides a novel solution, that can leverage carrier sense multiple access with
enhanced collision avoidance (CSMA/ECA) and adaptive sensitivity control
mechanisms, for enabling STR operation. The key aspects of the proposed
solution include co-existence with legacy nodes, identification of eligible
nodes for UFD, optimization of secondary BFD and UFD transmissions, and
creation of UFD opportunities. Performance evaluation demonstrates that the
proposed solution is effective in achieving the gains provided by STR
operation.
