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 IRS-PCA 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.

中文翻译：

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智能反射面辅助飞行员污染攻击及对策

考虑了时分双工无线通信系统中的导频污染攻击 (PCA)，其中窃听者 (Eve) 攻击反向导频传输阶段，以便窃听从发射机 Alice 传输到接收机 Bob 的数据。我们为 Eve 提出了一种新的 PCA 方案，其中 Eve 本身不发射任何信号，而是使用智能反射面 (IRS) 来反射 Bob 发送给 Alice 的导频。提出的新 PCA 方案，称为 IRS-PCA，在数据传输阶段增加了从 Alice 到 IRS 的信号泄漏，然后由 IRS 反射到 Eve，以提高 Eve 的窃听能力。由于使用 IRS-PCA，Eve 不再需要知道 Bob 的导频序列，因此提议的 IRS-PCA 方案禁用了许多现有的 PCA 对策，因此，对合法无线通信系统的安全构成严重威胁。鉴于此，本文考虑了1）IRS-PCA检测和2）IRS-PCA下的安全传输问题。针对IRS-PCA检测，基于最快检测框架提出了一种广义累积和(GCUSUM)检测程序，旨在一旦发生IRS-PCA，尽快检测其发生。针对IRS-PCA下的安全传输，提出了一种协作信道估计方案来估计IRS的信道，在此基础上设计了迫零波束成形以减少信号泄漏。针对IRS-PCA检测，基于最快检测框架提出了一种广义累积和(GCUSUM)检测程序，旨在一旦发生IRS-PCA，尽快检测其发生。针对IRS-PCA下的安全传输，提出了一种协作信道估计方案来估计IRS的信道，在此基础上设计了迫零波束成形以减少信号泄漏。针对IRS-PCA检测，基于最快检测框架提出了一种广义累积和(GCUSUM)检测程序，旨在一旦发生IRS-PCA，尽快检测其发生。针对IRS-PCA下的安全传输，提出了一种协作信道估计方案来估计IRS的信道，在此基础上设计了迫零波束成形以减少信号泄漏。