We propose a user selection scheme with secrecy capacity for multiuser MIMO downlink system whose goal is not to leak information to other users in the system. The transmitter can send confidential messages to each user securely. We evaluated system secrecy capacity. We also evaluated the system capacity and capacity-based fairness performance and showed that the proposed scheme has little performance degradation in terms of system capacity and fairness, while ensuring secrecy.
We propose a user selection scheme with secrecy capacity for multiuser MIMO downlink system whose goal is not to leak information to other users in the system. The transmitter can send confidential messages to each user securely. We evaluated system secrecy capacity. We also evaluated the system capacity and capacity-based fairness performance and showed that the proposed scheme has little performance degradation in terms of system capacity and fairness, while ensuring secrecy.
For multiuser Multiple-Input-Multiple-Output (MIMO) downlink systems where some receivers exist, several user selection schemes have been recently proposed. However, these user selection schemes do not take security into consideration. One possible scenario of wireless communication systems is that a transmitter sends confidential messages to multiple receivers in the presence of eavesdroppers. In this paper, we propose a user selection scheme with secrecy capacity for multiuser MIMO downlink system. We assume a system with a transmitter, some legitimate users and eavesdroppers where the transmitter wants to send data securely against eavesdroppers. In the proposed scheme, the transmitter selects a user set so that their secrecy capacities among legitimate users and eavesdroppers are larger than zero. Thus, the transmitter can send confidential messages to users securely. The proposed scheme can be applied to conventional scheduling schemes, such as maximum capacity (MAX) scheduling and proportional fairness (PF) scheduling. Simulation results show that the proposed scheme provides secure transmissions and has little degradation of performance of system capacity and fairness when applied to the conventional scheduling schemes. Hence, we show that the proposed scheme is an effective user selection scheme to guarantee secrecy of communication.
This paper investigates the ergodic secrecy sum-rate for the downlink multiuser MIMO system with independent confidential messages, each of which is intended for one of the users and should keep secret from others. We adopt zero-forcing beamforming with limited channel state information (CSI) feedback at the transmitter, and derive the closed-form expression for the ergodic secrecy sum-rate. Moreover, we analyze some of its asymptotic characteristics, which provide guidance on secure transmission design. Finally, all theoretical results are validated by numerical simulations.
This paper studies the privacy-preserving for downlink transmission in multiuser relay networks, where a source communicates with multiple users via a relay employing the amplify-and-forward protocol. Within any scheduling unit, only one user (desired user) is chosen for data reception, and the other users (undesired users) are viewed as potential eavesdroppers due to the broadcast nature of wireless medium. To prevent information leakage, we propose a physical-layer cooperative privacy preserving scheme, whose key idea is to schedule a cooperating user in addition to the desired user to deliver artificial noise (AN). By exploiting the characteristics of channels, the cooperating user carefully designs the AN transmitted during two time slots such that the AN can be canceled out at the desired user, but cannot be removed at the undesired users. As a result, the end-to-end signal-to-noise-ratio of any undesired user is heavily degraded, while that of the desired user is not seriously affected, thus preserving the data confidentiality of the desired user. To maximize the instantaneous secrecy rate, an opportunistic user selection criterion is developed. The lower bound of the ergodic secrecy rate (ESR) as well as the approximate upper bound of the secrecy outage probability is derived. The asymptotic performance of ESR is also analyzed via extreme value theory. Furthermore, to motivate users with heterogeneous channel conditions to participate in cooperation and guarantee the fairness among users, a user-grouping-based selection method is proposed. To evaluate the performance of this method, a novel concept called system fairness factor is introduced and studied. Theoretical analysis and simulation results show that, thanks to the proposed cooperative privacy preserving mechanism, the system ESR grows with the increasing number of users, and much higher secrecy rate and lower secrecy outage probability can be achieved compared with the existing schemes in the literature.
In this paper, we consider a homogenous multiantenna downlink network, where a passive eavesdropper intends to intercept the communication between a base station and multiple secure users (SUs) over Rayleigh fading channels. In order to guarantee the security of information transfer, physical-layer security is employed accordingly. For such a multiple user (MU) secure network, the number of accessing SUs, i.e., the transmission mode, has a great impact on the secrecy performance. Specifically, on one hand, a large number of accessing SUs will result in high interuser interference at SUs, resulting in a reduction in the capacity of the legitimate channel. On the other hand, high interuser interference will interfere with the eavesdropper and thus degrades the performance of the eavesdropper channel. Generally speaking, the harmful interuser interference may be transformed as a useful tool in antieavesdropping. The focus of this paper is on selecting the optimal transmission mode according to channel conditions and system parameters to maximize the sum secrecy outage capacity. Moreover, through asymptotic analysis, we present several simple mode selection schemes in some extreme cases. Finally, simulation results validate the effectiveness of the proposed mode selection schemes in MU secure communications.
Consider secure transmissions over the downlink of a multiuser MISO system with independent confidential messages, each of which is intended for one of the users and should keep secret from others. We are interested in a scenario where users have individual secrecy rate requirements. This scenario is practical but has drawn little attention in the literature so far. In this paper, we propose a secrecy rate balancing algorithm which tries to fulfill the secrecy rate requirements of users, and maximizes the minimum margin which is defined as the difference between the available secrecy rate and the required rate for each user. This algorithm balances out all the secrecy rate margins until an equilibrium is reached. We derive a necessary condition for the optimal solution. Finally, theoretical results are illustrated by numerical simulations.
This work develops a beamforming framework for energy efficiency optimization in MIMO multi-user systems with confidentiality constraints. Two channel models are considered, namely, a broadcast channel with confidential messages (corresponding to single-cell downlink) and an interference channel with confidential messages (corresponding to multi-cell downlink), in which multiple messages are transmitted, and it must be ensured that only the intended receiver is able to perform data decoding, thus treating non-intended receivers as potential eavesdroppers. In this multi-user scenario, the new metric global secrecy energy efficiency is introduced and optimized. Moreover, the coupling among the secrecy energy efficiencies of different users is analyzed by providing an efficient way of computing the system secrecy energy efficiency Pareto boundary. Both contributions are achieved by developing an optimization framework which suitably combines fractional programming theory and sequential optimization theory. The proposed framework is provably convergent, enjoys affordable complexity, and fulfills first-order optimality properties. Finally, the closed form conditions are provided to support smart user selection algorithms for downlink transmission.