In recent years, physical layer security has been regarded as a promising concept to provide secure communications in next generation mobile systems, where theoretically massive MIMO can significantly enhance the system secrecy performance due to its advantage in shaping the transmitted signals to null the interference or leakage. However, in practical systems, the channel state information is often imperfect due to the outdated channel effect and the channel estimation error. In this paper, we investigate the physical layer security problem in a multi-user massive MIMO system under imperfect CSI. We first derive a tight asymptotic lower bound of the ergodic system secrecy capacity under imperfect CSI, and then analyze how imperfect CSI affects the system secrecy performance. Simulation results reveal the negative impact of the imperfect CSI on the secrecy performance of massive MIMO systems and the accuracy of our theoretical derivations and analysis.
In recent years, physical layer security has been regarded as a promising concept to provide secure communications in next generation mobile systems, where theoretically massive MIMO can significantly enhance the system secrecy performance due to its advantage in shaping the transmitted signals to null the interference or leakage. However, in practical systems, the channel state information is often imperfect due to the outdated channel effect and the channel estimation error. In this paper, we investigate the physical layer security problem in a multi-user massive MIMO system under imperfect CSI. We first derive a tight asymptotic lower bound of the ergodic system secrecy capacity under imperfect CSI, and then analyze how imperfect CSI affects the system secrecy performance. Simulation results reveal the negative impact of the imperfect CSI on the secrecy performance of massive MIMO systems and the accuracy of our theoretical derivations and analysis.
In recent years, physical layer security has been regarded as a promising technique to facilitate secure communications in next generation mobile systems, where theoretically massive MIMO can significantly enhance the system secrecy performance under its advantage in shaping the transmitted signals to null the interference or leakage. However, in practical systems, the achievable secrecy performance under imperfect channel state information (CSI) deserves further investigation. In this paper, we give a detailed analysis about the physical layer security problem in a multi-user massive MIMO system with imperfect CSI. The considered imperfect CSI includes both the outdated CSI due to the transmission and processing delay, and the channel estimation error. We first derive a tight asymptotic lower bound of the ergodic system secrecy capacity under imperfect CSI, and then analyze how imperfect CSI affects the system secrecy performance. Moreover, we propose a channel prediction scheme that can result in more accurate CSI, in order to alleviate the negative effect on the achievable system secrecy capacity caused by imperfect CSI. Simulation results reveal that the imperfect CSI greatly reduces the system secrecy capacity, while our designed channel prediction scheme can effectively mitigate the harmful impact of imperfect CSI and thus improve the system secrecy performance.
In this paper, we consider a multi-cell MISO downlink, where a multi-antenna base station (BS) sends messages to its intended user, while a passive eavesdropper tries to intercept the information in each cell. Physical layer security is employed in order to guarantee information security. Due to incomplete channel state information (CSI) at BSs, residue inter-cell interference exists even with coordinated beamforming, which exerts a great impact on the secrecy performance. In this paper, we conduct a unified performance analysis for physical layer security with incomplete CSI, and derives closed-form expressions of ergodic secrecy rate, secrecy outage probability, and interception probability, considering CSI estimation accuracy, transmit signal to noise ratio (SNR), and channel condition. We reveal some insights on the secrecy performance through asymptotic analysis. Furthermore, based on the derived theoretical results, we propose a CSI exchange amount allocation scheme. Finally, the simulations validate our theoretical claims.
In this paper, we study the problem of physical layer security in a large-scale multiple-input multiple-output (LS-MIMO) relaying system. The advantage of LS-MIMO relaying systems is exploited to enhance both wireless security and spectral efficiency. In particular, the challenging issue incurred by short interception distance is well addressed. Under very practical assumptions, i.e., no eavesdropper's channel state information (CSI) and imperfect legitimate channel CSI, this paper gives a thorough investigation of the impact of imperfect CSI in two classic relaying systems, i.e., amplify-and-forward (AF) and decode-and-forward (DF) systems, and obtain explicit expressions of secrecy outage capacities for both cases. Finally, our theoretical claims are validated by the numerical results.
In this paper, secure communication aided by a multiantenna cooperative jammer is investigated. Under very practical but adverse assumptions, i.e., no instantaneous jammer–eavesdropper channel state information (CSI) and imperfect instantaneous jammer–receiver CSI, the residual interference from the jammer to the legitimate receiver appears, even with spatial beamforming. Then, this paper analyzes the impact of imperfect CSI on the function of cooperative jamming and derives closed-form expressions of multiple secrecy performance metrics, including ergodic secrecy rate, secrecy outage capacity, and interception probability. Interestingly, it is found that two antennas at the jammer is always optimal. Furthermore, some insights are obtained through asymptotic analysis, e.g., the secrecy performance is saturated as the source transmit power increases, the ergodic secrecy rate is a linear function of CSI feedback bits in the region of high transmit power at the source/jammer, and interception probability is independent of transmit power at the source and is a decreasing function of transmit power at the jammer. Finally, theoretical claims are validated by simulation results.
In this paper, we investigate the physical layer security of a multiple-input and multiple-output (MIMO) relay system under imperfect channel state information (CSI). We propose using multiple antennas at the source and destination to increase the signal-to-noise (SNR) gain of the primary channel, thus improving the system's security performance. Exact closed-form expression of the secure outage probability (SOP) and secrecy capacity (SC) are derived and verified by Monte-Carlo simulations. A close match between the theoretical and simulation results confirms the accurateness of our mathematical analysis. We show that the SOP decreases while the SC increases as the average SNR is higher. Furthermore, the saturated minimum and maximum values highly depend on the number of antennas at source and destination, the degree of imperfect CSI, and the location of eavesdropper.
In this paper, we investigate the system performance from the physical layer security provision under imperfect channel state information (CSI). In a classical transmitter (Alice)-legitimate receiver (Bob)- eavesdropper (Eve) model, we introduce artificial noise (AN) to disturb Eve's reception, as Eve's CSI is unknown to Alice. For designing the transmit beamforming vector of the information signal and precoding matrix of AN, Bob feeds back the quantized CSI estimation to Alice. Due to the effects of imperfect CSI at Alice, the secrecy system performance is upper bounded at high SNRs. In order to overcome the problem, by utilizing our derived upper bound on the secrecy rate loss, we put forward a scaled feedback strategy for the secrecy system. By employing the proposed strategy, the secrecy rate increases with transmit power despite that Alice can only obtain imperfect Bob's CSI, and the secrecy rate loss between perfect CSI and imperfect CSI can be controlled within a certain gap. Computer simulations are provided to verify our derived results.