Secure communication in multigroup multicasting cell-free massive MIMO networks with active spoofing attack

The authors investigate the secure communication in multigroup multicasting cell-free massive MIMO systems in the presence of an active pilot spoofing attack. With the imperfect estimated local channels at access points, a distributed conjugate beamforming with normalised power constraint policy is exploited for downlink multicasting transmission. Closed-form expressions for the per-user achievable rate and information leakage to eavesdropper are derived, respectively. Numerical results are presented to verify the correctness of their analytical results and quantitatively analyse the impacts of eavesdropper's spoofing pilot power and a number of groups on the secrecy performance of the considered systems.