2 research outputs found
Blind Channel Separation in Massive MIMO System under Pilot Spoofing and Jamming Attack
We consider a channel separation approach to counter the pilot attack in a
massive MIMO system, where malicious users (MUs) perform pilot spoofing and
jamming attack (PSJA) in uplink by sending symbols to the basestation (BS)
during the channel estimation (CE) phase of the legitimate users (LUs). More
specifically, the PSJA strategies employed by the MUs may include (i) sending
the random symbols according to arbitrary stationary or non-stationary
distributions that are unknown to the BS; (ii) sending the jamming symbols that
are correlative to those of the LUs. We analyze the empirical distribution of
the received pilot signals (ED-RPS) at the BS, and prove that its
characteristic function (CF) asymptotically approaches to the product of the
CFs of the desired signal (DS) and the noise, where the DS is the product of
the channel matrix and the signal sequences sent by the LUs/MUs. These
observations motivate a novel two-step blind channel separation method, wherein
we first estimate the CF of DS from the ED-RPS and then extract the alphabet of
the DS to separate the channels. Both analysis and simulation results show that
the proposed method achieves good channel separation performance in massive
MIMO systems
Intelligent Reflecting Surface Aided Pilot Contamination Attack and Its Countermeasure
Pilot contamination attack (PCA) in a time division duplex wireless
communication system is considered, where an eavesdropper (Eve) attacks the
reverse pilot transmission phase in order to wiretap the data transmitted from
a transmitter, Alice, to a receiver, Bob. We propose a new PCA scheme for Eve,
wherein Eve does not emit any signal by itself but uses an intelligent
reflecting surface (IRS) to reflect the pilot sent by Bob to Alice. The
proposed new PCA scheme, referred to as IRS-PCA, increases the signal leakage
from Alice to the IRS during the data transmission phase, which is then
reflected by the IRS to Eve in order to improve the wiretapping capability of
Eve. The proposed IRS-PCA scheme disables many existing countermeasures on PCA
due to the fact that with IRS-PCA, Eve no longer needs to know the pilot
sequence of Bob, and therefore, poses severe threat to the security of the
legitimate wireless communication system. In view of this, the problems of 1)
IRS-PCA detection and 2) secure transmission under IRSPCA are considered in
this paper. For IRS-PCA detection, a generalized cumulative sum (GCUSUM)
detection procedure is proposed based on the framework of quickest detection,
aiming at detecting the occurrence of IRS-PCA as soon as possible once it
occurs. For secure transmission under IRS-PCA, a cooperative channel estimation
scheme is proposed to estimate the channel of the IRS, based on which
zero-forcing beamforming is designed to reduce signal leakage.Comment: Accepted by IEEE Transactions on wireless communication