  The degrees of freedom (DoFs) attained in monostatic integrated sensing and
communications (ISAC) are analyzed. Specifically, monostatic sensing aims for
extracting target-orientation information from the line of sight (LoS) channel
between the transmitter and the target, since the Non-LoS (NLoS) paths only
contain clutter or interference. By contrast, in wireless communications,
typically, both the LoS and NLoS paths are exploited for achieving diversity or
multiplexing gains. Hence, we shed light on the NLoS exploitation vs. reduction
tradeoffs in a monostatic ISAC scenario. In particular, we optimize the
transmit power of each signal path to maximize the communication rate, while
guaranteeing the sensing performance for the target. The non-convex problem
formulated is firstly solved in closed form for a single-NLoS-link scenario,
then we harness the popular successive convex approximation (SCA) method for a
general multiple-NLoS-link scenario. Our simulation results characterize the
fundamental performance tradeoffs between sensing and communication,
demonstrating that the available DoFs in the ISAC channel should be efficiently
exploited in a way that is distinctly different from that of communication-only
scenarios.
