  Accurate channel state information (CSI) at the transmitter is critical for
maximizing spectral efficiency on the downlink of multi-antenna networks. In
this work we analyze a novel form of physical layer attacks on such closed-loop
wireless networks. Specifically, this paper considers the impact of
deliberately inaccurate feedback by malicious users in a multiuser multicast
system. Numerical results demonstrate the significant degradation in
performance of closed-loop transmission schemes due to intentional feedback of
false CSI by adversarial users.
