  With recent advancements, the wireless local area network (WLAN) or wireless
fidelity (Wi-Fi) technology has been successfully utilized to realize sensing
functionalities such as detection, localization, and recognition. However, the
WLANs standards are developed mainly for the purpose of communication, and thus
may not be able to meet the stringent sensing requirements in emerging
applications. To resolve this issue, a new Task Group (TG), namely IEEE
802.11bf, has been established by the IEEE 802.11 working group, with the
objective of creating a new amendment to the WLAN standard to provide advanced
sensing requirements while minimizing the effect on communications. This paper
provides a comprehensive overview on the up-to-date efforts in the IEEE
802.11bf TG. First, we introduce the definition of the 802.11bf amendment and
its standardization timeline. Then, we discuss the WLAN sensing procedure and
framework used for measurement acquisition, by considering both conventional
sensing at sub-7 GHz and directional multi-gigabit (DMG) sensing at 60 GHz,
respectively. Next, we present various candidate technical features for IEEE
802.11bf, including waveform/sequence design, feedback types, quantization, as
well as security and privacy. Finally, we describe the methodologies used by
the IEEE 802.11bf TG to evaluate the alternative performance. It is desired
that this overview paper provide useful insights on IEEE 802.11 WLAN sensing to
people with great interests and promote the IEEE 802.11bf standard to be widely
deployed.
