  This paper studies optimal communication and coordination strategies in
cyber-physical systems for both defender and attacker within a game-theoretic
framework. We model the communication network of a cyber-physical system as a
sensor network which involves one single Gaussian source observed by many
sensors, subject to additive independent Gaussian observation noises. The
sensors communicate with the estimator over a coherent Gaussian multiple access
channel. The aim of the receiver is to reconstruct the underlying source with
minimum mean squared error. The scenario of interest here is one where some of
the sensors are captured by the attacker and they act as the adversary
(jammer): they strive to maximize distortion. The receiver (estimator) knows
the captured sensors but still cannot simply ignore them due to the multiple
access channel, i.e., the outputs of all sensors are summed to generate the
estimator input. We show that the ability of transmitter sensors to secretly
agree on a random event, that is "coordination", plays a key role in the
analysis...
