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Anti-Jamming in Cell Free mMIMO systems

Recently, cell-free massive multiple-input multiple-output (mMIMO), a distributed version of mMIMO, has increasingly been deployed to increase the spectral and energy efficiency of communication systems. In this paper, we investigate the ability of using cell-free mMIMO to reduce the jamming attacks which is a critical issue for communication. We propose a full-stack framework from detecting to suppressing jamming attacks in cell-free mMIMO system. At first, we exploit the unused pilots to design a jammer detector based on the likelihood functions of the measured signals. Then, we propose a jamming suppression method including two tasks: jamming estimation and access point (AP) selection. In the first task, we estimate the phase and amplitude when projecting the received signals onto the unused pilots, and then use them to estimate the jamming signal. In the second task, we employ the neural network-contextual multi-armed bandit (NN-CMAB) for online selection of APs which can provide the multi-user spatial diversity considering the existence of the jammers. Furthermore, we also propose a power control strategy for managing the minimum rate requirement in multi-user settings. Numerical results confirm the advantages of proposed designs over conventional jamming-ignorant-LMMSE strategy in spectral efficiency.