In this paper, secure downlink transmission with artificial noise (AN) aided generalized spatial modulation (GSM) has been analyzed. The transmitter sends the precoded data to the legitimate receivers (LUs) and the eavesdropper (eve) overhears it. The main emphasis is laid on the effect of imperfect channel state information (CSI) and imperfect successive interference cancellation (SIC) on the secrecy capacity of LUs. AN is transmitted along with the information symbols to maintain the secrecy at the LUs. NOMA is used to transmit the data of all LUs at once. As precoding at the transmitter and AN designing is based on perfect CSI, hence imperfection in CSI leads to degradation in the capacity. Imperfection in SIC has been considered as an error in SIC at one user keeps repeating itself for other users. Monte-carlo simulations has been carried out to present the effect of both the errors simultaneously and separately on the capacity.
In this paper, secure downlink transmission with artificial noise (AN) aided generalized spatial modulation (GSM) has been analyzed. The transmitter sends the precoded data to the legitimate receivers (LUs) and the eavesdropper (eve) overhears it. The main emphasis is laid on the effect of imperfect channel state information (CSI) and imperfect successive interference cancellation (SIC) on the secrecy capacity of LUs. AN is transmitted along with the information symbols to maintain the secrecy at the LUs. NOMA is used to transmit the data of all LUs at once. As precoding at the transmitter and AN designing is based on perfect CSI, hence imperfection in CSI leads to degradation in the capacity. Imperfection in SIC has been considered as an error in SIC at one user keeps repeating itself for other users. Monte-carlo simulations has been carried out to present the effect of both the errors simultaneously and separately on the capacity.
For 5G wireless networks, one of the critical demands is security and privacy, which are particularly in multi-cell multi-user MIMO downlink communications. In this paper, we study secure transmission in the downlink of a multi-cell MIMO cellular network under imperfect channel state information (CSI). Multi-Cell Processing (MCP) and an artificial noise (AN) are employed for secrecy enhancement. For MCP, the BSs share the channel information and data symbols for all users to control inter-cell interference and information leakage. AN is added to degrade the eavesdropper's channel. Based on regularized channel inversion (RCI) precoding, we derive the concise formulas for the signal-to-interference plus noise ratio (SINR) at a legitimate user and an eavesdropper, and the achievable secrecy sum-rate with MCP and AN. Furthermore, we obtain their corresponding approximation in large-system regime. It shows that secrecy sum-rate can be greatly improved with MCP and AN under imperfect CSI, especially in high signal-to-noise ratio (SNR), the secrecy sum-rate stays a constant. The analytical results are validated with finite-size system by simulation.
Based on the objective reality of channel estimation error, this paper introduces a novel artificial noise (AN) aided spatial modulation (SM) secrecy-enhancing scheme under imperfect channel state information (CSI). In the proposed scheme, SM is used to activate one antenna from the transmit antennas, and the information symbols will be transmitted with the designed AN at each timeslot. By utilizing the legitimate channel's imperfect CSI, AN is generated across two adjacent timeslots. Because the CSI is known at the legitimate receiver, then it can perfectly cancel the AN. However, the eavesdropper knows nothing of the legitimate channel's CSI, so it can not recover any useful information from the AN. At the receiver, a new detection scheme that detects across two adjacent timeslots is also proposed. With imperfect CSI, the secrecy rate of the proposed scheme is derived over Rayleigh fading channels in order to investigate the performance. Moreover, based on the secrecy performance analysis, the lower bound of the ergodic secrecy rate (ESR), the corresponding closed form of the lower bound, and the approximated expression are also derived. The simulation results verified in this paper prove that the proposed scheme with imperfect CSI can achieve satisfactory performance.
This paper investigates secure transmission for non-orthogonal multiple access (NOMA) systems where the imperfect successive interference cancellation (SIC) is considered at both legitimate users and eavesdropper (Eve). A power allocation scheme is designed for the legitimate users to mitigate the effect of the SIC error caused by imperfect SIC. For characterizing the secrecy performance of the NOMA system, the closed-form expressions for connection outage probability (COP), secrecy outage probability (SOP), and effective secrecy throughput (EST) are derived over Nakagami-m fading channels in both NOMA and benchmark orthogonal multiple access (OMA) systems. We also provide security and reliability trade-off results (SRT) for the users in the NOMA and OMA systems. Simulation results verify our analysis and show that the strong users achieve better secrecy performance but worse reliability performance and NOMA outperforms OMA in terms of SRT.
In this paper, we present a new secrecy-enhancing scheme for the spatial modulation (SM) system, by considering imperfect channel state information (CSI). In the proposed scheme, two antennas are activated at the same time. One of the activated antennas transmits information symbols along with artificial noise (AN) optimized under the imperfect CSI condition. On the other hand, the other activated antenna transmits another AN sequence. Because the AN are generated by exploiting the imperfect CSI of the legitimate channel, they can only be canceled at the legitimate receiver, while the passive eavesdropper will suffer from interference. We derive the secrecy rate of the proposed scheme in order to estimate the performance. The numerical results demonstrated in this paper verify that the proposed scheme can achieve a better secrecy rate compared to the conventional scheme at the same effective data rate.
The security of information over wireless channels has always been an important aspect of wireless communication research. In this paper, the secrecy performance of a spatial modulated system with an artificial noise is investigated over the Rayleigh channel, and the corresponding secrecy rate is analyzed in the presence of imperfect channel state information (CSI). Based on the secrecy performance analysis, the ergodic rates and the corresponding lower bounds of the legitimate receiver and eavesdropper are, respectively, derived. As a result, the closed-form lower bound of ergodic rate of the legitimate receiver is obtained, and the lower bound of ergodic rate of the eavesdropper and the corresponding ergodic secrecy rate (ESR) can be achieved by calculating the mean values. To avoid the mean operation and reduce the complexity, the closed-form approximated expression of ESR is also derived. This theoretical ESR can include the one under perfect CSI as a special case and has the value close to the corresponding simulation. Thus, it can provide good performance evaluation for the artificial-noise-aided spatial modulation system with imperfect CSI. Simulation results verify the effectiveness of the theoretical analysis. The system with imperfect CSI is found to have low ESR as compared to the one with perfect CSI due to the estimation error. Moreover, initially, the ESR increases with increasing power of artificial noise, but then, due to the total power constraint, it starts decreasing.
In this paper, we design a secure transmission scheme in uplink and downlink of non-orthogonal multiple access (NOMA) system. In this scenario, two pairs of base stationuser can operate under the presence of eavesdropper. The relay plays an important role to forward signals from group of base stations to serve distant users. However, the eavesdropper can overhear signal which leads to secure performance need be reconsidered. To provide secure performance, we derive the closed-form expressions for strictly positive secrecy capacity (SPSC). In addition, we rely on relay for enlarge coverage area. The channel conditions meet imperfect channel state information (CSI) which shows degraded secure performance. Results confirm the relationship between transmit power at the source and and SPSC how many main parameters affecting secure performance metric. Furthermore, simulation results show that the uplink and downlink NOMA technique improves secure performance in the low SPSC region. We further conduct analysis by using Monte-Carlo simulations.