  This paper considers multiple-input multiple-output (MIMO) full-duplex (FD)
two-way secrecy systems. Specifically, both multi-antenna FD legitimate nodes
exchange their own confidential message in the presence of an eavesdropper.
Taking into account the imperfect channel state information (CSI) of the
eavesdropper, we formulate a robust sum secrecy rate maximization (RSSRM)
problem subject to the outage probability constraint of the achievable sum
secrecy rate and the transmit power constraint. Unlike other existing channel
uncertainty models, e.g., norm-bounded and Gaussian-distribution, we exploit a
moment-based random distributed CSI channel uncertainty model to recast our
formulate RSSRM problem into the convex optimization frameworks based on a
Markov's inequality and robust conic reformulation, i.e., semidefinite
programming (SDP). In addition, difference-of-concave (DC) approximation is
employed to iteratively tackle the transmit covariance matrices of these
legitimate nodes. Simulation results are provided to validate our proposed FD
approaches.
