  Driven by the intelligent applications of sixth-generation (6G) mobile
communication systems such as smart city and autonomous driving, which connect
the physical and cyber space, the integrated sensing and communication (ISAC)
brings a revolutionary change to the base stations (BSs) of 6G by integrating
radar sensing and communication in the same hardware and wireless resource.
However, with the requirements of long-range and accurate sensing in the
applications of smart city and autonomous driving, the ISAC enabled single BS
still has a limitation in the sensing range and accuracy. With the networked
infrastructures of mobile communication systems, multi-BS cooperative sensing
is a natural choice satisfying the requirement of long-range and accurate
sensing. In this article, the framework of multi-BS cooperative sensing is
proposed, breaking through the limitation of single-BS sensing. The enabling
technologies, including unified ISAC performance metrics, ISAC signal design
and optimization, interference management, cooperative sensing algorithms, are
introduced in details. The performance evaluation results are provided to
verify the effectiveness of multi-BS cooperative sensing schemes. With ISAC
enabled multi-BS cooperative sensing (ISAC-MCS), the intelligent
infrastructures connecting physical and cyber space can be established,
ushering the era of 6G promoting the intelligence of everything.
