1,358 research outputs found
On Robustness of Massive MIMO Systems Against Passive Eavesdropping under Antenna Selection
In massive MIMO wiretap settings, the base station can significantly suppress
eavesdroppers by narrow beamforming toward legitimate terminals. Numerical
investigations show that by this approach, secrecy is obtained at no
significant cost. We call this property of massive MIMO systems `secrecy for
free' and show that it not only holds when all the transmit antennas at the
base station are employed, but also when only a single antenna is set active.
Using linear precoding, the information leakage to the eavesdroppers can be
sufficiently diminished, when the total number of available transmit antennas
at the base station grows large, even when only a fixed number of them are
selected. This result indicates that passive eavesdropping has no significant
impact on massive MIMO systems, regardless of the number of active transmit
antennas.Comment: 7 pages, 2 figures; To be presented in IEEE Global Communications
Conference (Globecom) 2018 in Abu Dhabi, UA
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Secure Communication for Spatially Sparse Millimeter-Wave Massive MIMO Channels via Hybrid Precoding
In this paper, we investigate secure communication over sparse millimeter-wave (mm-Wave) massive multiple-input multiple-output (MIMO) channels by exploiting the spatial sparsity of legitimate user's channel. We propose a secure communication scheme in which information data is precoded onto dominant angle components of the sparse channel through a limited number of radio-frequency (RF) chains, while artificial noise (AN) is broadcast over the remaining nondominant angles interfering only with the eavesdropper with a high probability. It is shown that the channel sparsity plays a fundamental role analogous to secret keys in achieving secure communication. Hence, by defining two statistical measures of the channel sparsity, we analytically characterize its impact on secrecy rate. In particular, a substantial improvement on secrecy rate can be obtained by the proposed scheme due to the uncertainty, i.e., 'entropy', introduced by the channel sparsity which is unknown to the eavesdropper. It is revealed that sparsity in the power domain can always contribute to the secrecy rate. In contrast, in the angle domain, there exists an optimal level of sparsity that maximizes the secrecy rate. The effectiveness of the proposed scheme and derived results are verified by numerical simulations
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