  In this paper, we propose a framework for protecting the uplink transmission
of a massive multiple-input multiple-output (mMIMO) system from a jamming
attack. Our framework includes a novel minimum mean-squared error based jamming
suppression (MMSE-JS) estimator for channel training and a linear zero-forcing
jamming suppression (ZFJS) detector for uplink combining. The MMSE-JS exploits
some intentionally unused pilots to reduce the pilot contamination caused by
the jammer. The ZFJS suppresses the jamming interference during the detection
of the legitimate users' data symbols. The implementation of the proposed
framework is practical, since the complexities of computing the MMSE-JS and the
ZFJS are linear (not exponential) with respect to the number of antennas at the
base station and linear detectors with the same complexities as the ZFJS have
been already fabricated using 28 nm FD-SOI (Fully Depleted Silicon On
Insulator) technology in [12] and Xilinx Virtex-7 XC7VX690T FPGA in [13] for
the mMIMO systems. Our analysis shows that the jammer cannot dramatically
affect the performance of a mMIMO system equipped with the combination of
MMSE-JS and ZFJS. Numerical results confirm our analysis.
