We propose an antenna switching scheme in the full-duplex wiretap channel where the legitimate receiver, equipped with two antennas, operates in a full-duplex mode. We focus on a practical eavesdropping scenario where the instantaneous channel state information of the eavesdropper's channel is not available at the transmitter and the receiver. In our proposed scheme, the receiver selects the antenna that maximizes the main channel gain as the receive antenna and uses the remaining antenna to transmit jamming signals. We derive an exact expression for the secrecy outage probability to evaluate the secrecy performance of our new scheme. This expression allows us to quantify the secrecy performance gain of our proposed scheme relative to a standard antenna predetermination scheme where the receive and transmit antennas at the receiver are predetermined. We demonstrate that our scheme achieves a lower secrecy outage probability than the antenna predetermination scheme. We also show that our scheme achieves the full secrecy diversity order whereas the antenna predetermination scheme does not.
We propose an antenna switching scheme in the full-duplex wiretap channel where the legitimate receiver, equipped with two antennas, operates in a full-duplex mode. We focus on a practical eavesdropping scenario where the instantaneous channel state information of the eavesdropper's channel is not available at the transmitter and the receiver. In our proposed scheme, the receiver selects the antenna that maximizes the main channel gain as the receive antenna and uses the remaining antenna to transmit jamming signals. We derive an exact expression for the secrecy outage probability to evaluate the secrecy performance of our new scheme. This expression allows us to quantify the secrecy performance gain of our proposed scheme relative to a standard antenna predetermination scheme where the receive and transmit antennas at the receiver are predetermined. We demonstrate that our scheme achieves a lower secrecy outage probability than the antenna predetermination scheme. We also show that our scheme achieves the full secrecy diversity order whereas the antenna predetermination scheme does not.
We propose and analyze transmit antenna selection (TAS) to enhance physical layer security in a wiretap channel with multiple antennas at the transmitter, the receiver, and the eavesdropper. We consider the practical scenario of passive eavesdropping, where the transmitter does not have any channel state information (CSI) of the eavesdropper's channel. In the main channel between the transmitter and the receiver, we select a single antenna at the transmitter that maximizes the instantaneous signal-to-noise ratio (SNR) at the receiver. At the receiver and the eavesdropper, we consider two combining techniques: 1) maximal-ratio combining (MRC) and 2) selection combining (SC). For non-identical Rayleigh fading between the main channel and the eavesdropper's channel, we first derive new closed-form expressions for the exact and asymptotic secrecy outage probabilities. The asymptotic results accurately reveal the secrecy diversity order and the secrecy array gain. Next, we derive new closed-form expressions for the probability of positive secrecy and characterize the ε-outage secrecy capacity. We show that, under TAS/MRC and TAS/SC protocols, the secrecy outage probability approaches zero and the ε-outage secrecy capacity increases with increasing number of transmitter antennas.
We propose and analyze transmit antenna selection (TAS) to enhance physical layer security in a wiretap channel with NAantennas at the transmitter, NBantennas at the receiver, and NEantennas at the eavesdropper. We focus on the practical scenario where the transmitter does not have any channel state information (CSI) of the eavesdropper's channel. The transmitter selects a single antenna that maximizes the instantaneous signal-to-noise ratio (SNR) at the receiver. The receiver and the eavesdropper employ either maximal-ratio combining (MRC) or selection combining (SC) to combine the received signals. For the proposed protocols, we derive new closed-form expressions for the probability of non-zero secrecy capacity. We consider Nakagami-m fading with non-identical fading parameters of the main channel, mB, and of the eavesdropper's channel, mE. Next, we derive new closed-form expressions for the exact secrecy outage probability, based on which the ε-outage secrecy capacity is characterized. Based on the exact expressions, we derive the asymptotic secrecy outage probability which accurately reveals the secrecy diversity order and the secrecy array gain. We confirm that the proposed protocols achieve identical secrecy diversity orders of NANBmB. An interesting conclusion is reached that this diversity order is independent of NEand mE. Furthermore, we prove that under the proposed protocols, the secrecy outage probability and the ε-outage secrecy capacity improve with increasing NA.
In this paper, we investigate the secrecy performance of full-duplex multi-antenna spectrum-sharing wiretap networks in which a jamming signal is simultaneously transmitted by the full-duplex secondary receiver (Bob) based on the zero forcing beamforming (ZFB) algorithm. For the security enhancement, we propose the two antenna reception schemes: 1) random selection combining (RSC) where Bob selects LB antennas at random to combine the received signals and 2) generalized selection combining (GSC) where Bob selects LB strongest antennas to combine the received signals. We derive the exact closed-form expressions for the secrecy outage probability of full-duplex multi-antenna spectrum-sharing wiretap networks with ZFB algorithm. In order to explore a new design of the proposed schemes, we provide tractable asymptotic approximations for the secrecy outage probability in high signal-to-noise ratio regime under two distinct scenarios. From the analysis, we demonstrate that: 1) when the main channel is much better than the eavesdropper's channel, GSC/ZFB scheme achieves full diversity NB, while RSC/ZFB scheme only achieves partial diversity LB and 2) GSC/ZFB scheme achieves better secrecy performance than RSC/ZFB with different antenna numbers at Bob.
We investigate the secrecy rate optimization problem in a wiretap channel with a single-antenna source, a single-antenna eavesdropper, and a multiple-antenna full-duplex (FD) destination. To fully utilize the spatial degrees-of-freedom of multiple antennas, the function of antennas at the destination is not predefined, i.e., each antenna can operate in a transmit or receive mode. We propose a low-complexity near-optimal joint optimization scheme by jointly applying the dynamic antenna mode switching (AMS) and optimal power allocation (OPA) techniques, to maximize the secrecy rate of the FD destination-based jamming (DBJ) system. The proposed joint optimization scheme is valid for two different eavesdropping channel state information (ECSI) availability cases, i.e., instantaneous ECSIs and statistical ECSIs. Specifically, closed-form expressions of OPA factors are first derived, and then the optimal transmit and receive antennas sets at the destination are determined by combining the OPA factor and applying a greedy-search-based AMS approach for both ECSIs availabilities, respectively. Moreover, through complexity analysis, the search complexity of the proposed scheme is proven to be significantly reduced compared with the exhaustive searching method. Simulation results verify the secrecy performance superiority of the proposed scheme over the conventional FD-DBJ method.
In this paper, a novel transmit antenna selection scheme for multiple input multiple output (MIMO) wiretap channels is proposed. This new scheme achieves higher secrecy performance by exploiting eavesdropper's channel state information. The key idea behind our proposal is to perform the antenna selection aiming to maximize the overall secrecy rate instead of maximizing the instantaneous signal-to-noise ratio of the main channel. In our analysis, we assume that the legitimate receiver and the eavesdropper employ a maximal-ratio combining technique to combine the received signals from the transmitter. Considering Nakagami-m fading channels, a closed-form expression for the secrecy outage probability is derived, which can be used as a quality of service metric. Further, an asymptotic analysis is carried out and the diversity/array gains are obtained. The ergodic secrecy rate is also investigated for the case of multiple input single output wiretap channels. Representative numerical examples are plotted and validated through Monte Carlo simulations. Insightful discussions are drawn from the proposed analysis.
Abstract In this paper, we propose a hybrid scheme called transmit antenna selection and receiver’s artificial noise (TAS–rAN) for security enhancement in multiple-input single-output (MISO) wiretap channels. In this scheme, by using TAS protocol, the transmitter selects a single antenna that maximizes the instantaneous signal-to-noise ratio (SNR) at the full-duplex receiver. While the transmitter uses this antenna to transmit secrecy data, the full-duplex receiver would send artificial noise (AN) to confuse the potential eavesdropper. For the proposed protocol, we consider Rayleigh fading channels with different parameters for the main channel and the eavesdropper’s channel, and derive new closed-form expressions for the exact secrecy outage probability and the asymptotic secrecy outage probability. We demonstrate that the proposed TAS–