  The future of location-aided applications is shaped by the ubiquity of
Internet-of-Things devices. As an increasing amount of commercial off-the-shelf
radio devices support channel response collection, it is possible to achieve
fine-grained position estimation at a relatively low cost. In this paper, we
focus on the channel response-based positioning and tracking for various
applications. We first give an overview of the state of the art (SOTA) of
channel response-enabled localization, which is further classified into two
categories, i.e., device-based and contact-free schemes. A taxonomy for these
complementary approaches is provided concerning the involved techniques. Then,
we present a micro-benchmark of channel response-based direct positioning and
tracking for both device-based and contact-free schemes. Finally, some
practical issues for real-world applications and future research opportunities
are pointed out.
