  Integrated sensing and communication (ISAC) creates a platform to exploit the
synergy between two powerful functionalities that have been developing
separately. However, the interference management and resource allocation
between sensing and communication have not been fully studied. In this paper,
we consider the design of perceptive mobile networks (PMNs) by adding sensing
capability to current cellular networks. To avoid the full-duplex operation, we
propose the PMN with distributed target monitoring terminals (TMTs) where
passive TMTs are deployed over wireless networks to locate the sensing target
(ST). We jointly optimize the transmit and receive beamformers towards the
communication user terminals (UEs) and the ST by alternating-optimization (AO)
and prove its convergence. To reduce computation complexity and obtain physical
insights, we further investigate the use of linear transceivers, including zero
forcing and beam synthesis (B-syn). Our analysis revealed interesting physical
insights regarding interference management and resource allocation between
sensing and communication: 1) instead of forming dedicated sensing signals, it
is more efficient to redesign the communication signals for both communication
and sensing purposes and "leak" communication energy for sensing; 2) the amount
of energy leakage from one UE to the ST depends on their relative locations.
