  The synergetic gains of spectrum sharing and millimeter wave communication
networks have recently attracted attention, owing to the interference canceling
benefits of highly-directional beamforming in such systems. In principle,
fine-tuned coordinated scheduling and beamforming can drastically reduce
cross-operator interference. However, this goes at the expense of the exchange
of global channel state information, which is not realistic in particular when
considering inter-operator coordination. Indeed, such an exchange of
information is expensive in terms of backhaul infrastructure, and besides, it
raises sensitive privacy issues between otherwise competing operators. In this
paper, we expose the existence of a trade-off between coordination and privacy.
We propose an algorithm capable of balancing spectrum sharing performance with
privacy preservation based on the sharing of a low-rate beam-related
information. Such information is subject to a data obfuscation mechanism
borrowed from the digital security literature so as to control the privacy,
measured in terms of information-theoretical equivocation.
