  Simultaneous localization and mapping (SLAM) is a key technology that
provides user equipment (UE) tracking and environment mapping services,
enabling the deep integration of sensing and communication. The millimeter-wave
(mmWave) communication, with its larger bandwidths and antenna arrays,
inherently facilitates more accurate delay and angle measurements than sub-6
GHz communication, thereby providing opportunities for SLAM. However, none of
the existing works have realized the SLAM function under the 5G New Radio (NR)
standard due to specification and hardware constraints. In this study, we
investigate how 5G mmWave communication systems can achieve situational
awareness without changing the transceiver architecture and 5G NR standard. We
implement 28 GHz mmWave transceivers that deploy OFDM-based 5G NR waveform with
160 MHz channel bandwidth, and we realize beam management following the 5G NR.
Furthermore, we develop an efficient successive cancellation-based angle
extraction approach to obtain angles of arrival and departure from the
reference signal received power measurements. On the basis of angle
measurements, we propose an angle-only SLAM algorithm to track UE and map
features in the radio environment. Thorough experiments and ray tracing-based
computer simulations verify that the proposed angle-based SLAM can achieve
sub-meter level localization and mapping accuracy with a single base station
and without the requirement of strict time synchronization. Our experiments
also reveal many propagation properties critical to the success of SLAM in 5G
mmWave communication systems.
