On the secrecy degrees of freedom of miso wiretap channels with delayed CSIT

隆太郎 松本, Ryutaroh Matsumoto

Sheng Yang, Pablo Piantanida, Mari Kobayashi +1 more

The secrecy degrees of freedom (SDoF) of the Gaussian multiple-input and single-output (MISO) wiretap channel is studied under the assumption that delayed channel state information (CSI) is available at the transmitter and each receiver knows its own instantaneous channel. Such scenario is of practical interest since the legitimate receiver may send its channel states to the transmitter which is overheard by the eavesdropper. We first show that a strictly positive SDoF can be guaranteed whenever the transmitter has delayed CSI (either on the legitimate channel or/and the eavesdropper channel). In particular, in the case with delayed CSI on both channels, it is shown that the optimal SDoF is 2=3. We then generalize the result to the two-user Gaussian MISO broadcast channel with confidential messages and characterize the SDoF region when the transmitter has delayed CSI of both receivers. Interestingly, the artificial noise schemes are shown to provide the optimal SDoF region by masking the confidential message to the unintended receiver while aligning the interference at each receiver.

Oussama Souihli, Tomoaki Otsuki Ohtsuki

Mari Kobayashi, Sheng Yang, Giovanni Geraci

We consider the time-correlated multiple-input single-output (MISO) wiretap channel where a multi-antenna transmitter wishes to convey a confidential message to its receiver in the presence of an eavesdropper. Assuming that the transmitter with delayed channel state information acquires some knowledge on current channel state due to the temporal correlation, the secrecy degrees of freedom (SDoF), capturing the behavior of the secrecy capacity in high signal-to-noise ratio regime, is studied. We characterize the optimal SDoF and provide the achievable scheme that takes advantage of both spatial precoding and digitalized artificial noise alignment.

Zhao Wang, Ming Xiao, Mikael Skoglund +1 more

The secrecy degrees of freedom (SDOF) of the multiple-input single-output (MISO) broadcast channel with confidential messages (BCC) is studied. The network consists of a two-antenna transmitter and two single-antenna receivers, each demanding a confidential message from the transmitter. The problem is investigated with mixed channel state information at transmitter (CSIT), which is a combination of perfect delayed CSIT and inaccurate current CSIT. When the variance of the estimation error for the current CSIT scales with O(P-α), with α ∈ [0, 1], it is shown that the optimal sum SDOF of the considered BCC is 1+α. Furthermore, the optimal SDOF region of the considered MISO BCC is shown to be a polygon scaling with α. The proposed scheme is based on an artificial noise alignment that can combine the benefits of both types of delayed and current CSIT. These results can be seen as an extension of results of Yang et al. and Gou-Jafar to multiuser networks with secrecy constraints.

Mustafa El-Halabi