  The 6th generation (6G) wireless networks will likely to support a variety of
capabilities beyond communication, such as sensing and localization, through
the use of communication networks empowered by advanced technologies.
Integrated sensing and communication (ISAC) has been recognized as a critical
technology as well as an usage scenario for 6G, as widely agreed by leading
global standardization bodies. ISAC utilizes communication infrastructure and
devices to provide the capability of sensing the environment with high
resolution, as well as tracking and localizing moving objects nearby. Meeting
both the requirements for communication and sensing simultaneously, ISAC based
approaches celebrate the advantages of higher spectral and energy efficiency
compared to two separate systems to serve two purposes, and potentially lower
costs and easy deployment. A key step towards the standardization and
commercialization of ISAC is to carry out comprehensive field trials in
practical networks, such as the 5th generation (5G) network, to demonstrate its
true capacities in practical scenarios. In this paper, an ISAC based outdoor
multi-target detection, tracking and localization approach is proposed and
validated in 5G networks. The proposed system comprises of 5G base stations
(BSs) which serve nearby mobile users normally, while accomplishing the task of
detecting, tracking and localizing drones, vehicles and pedestrians
simultaneously. Comprehensive trial results demonstrate the relatively high
accuracy of the proposed method in practical outdoor environment when tracking
and localizing single targets and multiple targets.
