This paper proposes a new hybrid secure transmission scheme, TAS-SC-ZFB for wireless sensor networks (WSNs). This scheme uses transmit antenna selection (TAS) at the base station (BS) and adopts selection combining (SC) over legitimate nodes. Aditionally, zeroforcing beamforming (ZFB) is applied at the friendly jammer to confuse the effects of the eavesdropping node. Particularly, exact closed-form expressions for the secrecy outage probability (SOP) and the effective secrecy throughput are derived. Using these expressions, the optimal power allocation factor between the BS and jammer and optimal secrecy rate are obtained to minimize the SOP and maximize the secrecy throughput, respectively. Numerical results are used to validate the theoretical analysis and to compare with the existing state of the art.
This paper proposes a new hybrid secure transmission scheme, TAS-SC-ZFB for wireless sensor networks (WSNs). This scheme uses transmit antenna selection (TAS) at the base station (BS) and adopts selection combining (SC) over legitimate nodes. Aditionally, zeroforcing beamforming (ZFB) is applied at the friendly jammer to confuse the effects of the eavesdropping node. Particularly, exact closed-form expressions for the secrecy outage probability (SOP) and the effective secrecy throughput are derived. Using these expressions, the optimal power allocation factor between the BS and jammer and optimal secrecy rate are obtained to minimize the SOP and maximize the secrecy throughput, respectively. Numerical results are used to validate the theoretical analysis and to compare with the existing state of the art.
In this paper, we investigate the secure transmission in wireless sensor networks (WSNs) consisting of one multiple-antenna base station (BS), multiple single-antenna legitimate users, one single-antenna eavesdropper and one multiple-antenna cooperative jammer. In an effort to reduce the scheduling complexity and extend the battery lifetime of the sensor nodes, the switch-and-stay combining (SSC) scheduling scheme is exploited over the sensor nodes. Meanwhile, transmit antenna selection (TAS) is employed at the BS and cooperative jamming (CJ) is adopted at the jammer node, aiming at achieving a satisfactory secrecy performance. Moreover, depending on whether the jammer node has the global channel state information (CSI) of both the legitimate channel and the eavesdropper's channel, it explores a zero-forcing beamforming (ZFB) scheme or a null-space artificial noise (NAN) scheme to confound the eavesdropper while avoiding the interference to the legitimate user. Building on this, we propose two novel hybrid secure transmission schemes, termed TAS-SSC-ZFB and TAS-SSC-NAN, for WSNs. We then derive the exact closed-form expressions for the secrecy outage probability and the effective secrecy throughput of both schemes to characterize the secrecy performance. Using these closed-form expressions, we further determine the optimal switching threshold and obtain the optimal power allocation factor between the BS and jammer node for both schemes to minimize the secrecy outage probability, while the optimal secrecy rate is decided to maximize the effective secrecy throughput for both schemes. Numerical results are provided to verify the theoretical analysis and illustrate the impact of key system parameters on the secrecy performance.
This paper investigates secure communications of energy harvesting untrusted relay networks, where the destination assists jamming signal to prevent the untrusted relay from eavesdropping and to improve the forwarding ability of the energy constrained relay. Firstly, the source and the destination transmit the signals to the relay with maximal ratio transmission (MRT) technique or transmit antenna selection (TAS) technique. Then, the destination utilizes maximal ratio combining (MRC) technique or receive antenna selection (RAS) technique to receive the forwarded information. Therefore, four transmission and reception schemes are considered. For each scheme, the closed-form expressions of the secrecy outage probability (SOP) and the connection outage probability (COP) are derived. Besides, the effective secrecy throughput (EST) metric is analyzed to achieve a good tradeoff between security and reliability. In addition, the asymptotic performance of EST is also considered at the high signal-to-noise ratio (SNR). Finally, simulation results illustrate that: (1) the EST of the system with MRT and MRC scheme are superior to other schemes, however, in the high SNR regime, the EST of the system with MRT scheme is inferior to TAS; and (2) for the source node, there exists an optimal number of antennas to maximize the EST of the proposed schemes.
In this paper, the joint receiving antenna selection and full-duplex zero-forcing jamming scheme is presented to safeguard the information transmission of the multi-antenna wireless-powered networks. The performance of the connection outage probability, the secrecy outage probability, and the secrecy throughput are investigated whose closed-form expressions are derived. It is shown that the COP and the SOP are decreasing and increasing functions of the transmit power of jamming node and its antennae number, and , respectively. Moreover, the findings indicate the existence of an optimum secrecy rate per channel use for maximizing the ST. Besides, we also find that at the low regime of , the decline of COP with the increasing of is dominant to ST and the increment of SOP can be ignored, which turns to the opposite at the high regime. This result implies that a smaller is suggested at the low regime of while a larger one is preferred at the high regime for pursuing a better ST performance. Numerical simulations are carried out to validate the preciseness of the theoretical analysis.
In this paper, we addressed improving the physical layer security (PLS) of an energy harvest- ing (EH)-based wireless network composed of a source node, which is operated by the harvested energy from the power beacon and sends secure information to a destination in the presence of an eavesdropper and a cooperative jammer (CJ). In particular, we provided an explicit transmit design for minimizing the secrecy outage probability (SOP), subject to a minimum secrecy rate constraint. The results show that support from a friendly jammer can significantly improve the reliabil- ity and security performance of the system. Addition- ally, we described the effects of particular factors on the optimal possible temporal distribution between informa- tion transmission and energy harvesting. As a result, when considering the SOP, we concluded that there ex- ists an optimal value of the time switching factor for the system to function well. The analytical formulas were verified by Monte Carlo simulation.
In this paper, we propose a novel transmit antenna selection (TAS) scheme to improve the physical layer security of two-user non-orthogonal multiple access (NOMA) systems. Specifically, the proposed TAS scheme aims to select an antenna that is the most robust against the interception of an eavesdropper, in particular, the antenna that minimizes the maximum capacity of the eavesdropper channels. To evaluate the performance of the proposed scheme, we derive an exact closed-form expression for the secrecy outage probability (SOP) of the near user and a tight approximated closed-form expression for the SOP of the far user. Numerical results reveals that the proposed TAS scheme improves the total secrecy outage probability compared to that of some existing schemes. We also provide some insightful discussions on the impact of the number of antenna and the location of the eavesdropper on the security capability of the considered system.
We introduce an opportunistic scheduling to enhance the physical layer security with transmit antenna selection (TAS) in multiuser environment. We consider a wireless communication system composed of a single transmitter and multiple legitimate users in the presence of several eavesdroppers with each node having multiple antennas under quasi-static Rayleigh fading channel. The transmitter selects the best transmitting antenna and the best user to maximize signal-to-noise ratio (SNR) at the selected user. The user and eavesdropper can employ either selection combining (SC) or maximal ratio combining (MRC) to combine the received signals. New closed-form expressions for probability of positive secrecy and outage are derived. Moreover, asymptotic analysis reveals the outage diversity gain and array gain for the proposed scheme. The impact of number of users, eavesdroppers, and antennas on secrecy performance are clearly demonstrated with mathematical analysis and numerical results.