Tiep Minh Hoang

Cooperative Beamforming and User Selection for Improving the Security of Relay-Aided Systems

A relay network in which a source wishes to convey a confidential message to a legitimate destination with the assistance of trusted relays is considered. In particular, cooperative beamforming and user selection techniques are applied to protect the confidential message. The secrecy rate (SR) and secrecy outage probability (SOP) of the network are investigated first, and a tight upper bound for the SR and an exact formula for the SOP are derived. Next, asymptotic approximations for the SR and SOP in the high signal-to-noise ratio (SNR) regime are derived for two different schemes: 1) cooperative beamforming and 2) multiuser selection. Furthermore, a new concept of cooperative diversity gain, namely, adapted cooperative diversity gain (ACDG), which can be used to evaluate the security level of a cooperative relaying network, is investigated. It is shown that the ACDG of cooperative beamforming is equal to the conventional cooperative diversity gain of traditional multiple-input single-output networks, while the ACDG of the multiuser scenario is equal to that of traditional single-input multiple-output networks.

Physical Layer Security in Cooperative Energy Harvesting Networks With a Friendly Jammer

In this letter, we consider a cooperative wireless network consisting of a source, multiple intermediate energy harvesting nodes, and a destination, in the presence of a passive eavesdropper. First, the intermediate nodes use the time switching-based relaying protocol to harvest energy from the source signal. Then, a pair out of intermediate nodes are selected as a relay and a jammer to transmit confidential and jamming signals to the destination and eavesdropper. Under these assumptions, we evaluate the system performance in terms of secrecy outage probability.

Generalised selection at multi-antenna sources in two-way relay networks

A generalised selection transmission (GST) and generalised selection combining (GSC) scheme is proposed for two-way relay networks where two multi-antenna sources exchange information via a single-antenna relay. New exact and asymptotic expressions are derived for the outage probability and symbol error rate (SER) in Rayleigh fading. Moreover, a tight upper bound on the ergodic sum-rate is presented. These results are used to demonstrate that the proposed GST/GSC scheme preserves the full diversity order, which equals the minimum number of antennas at the two sources. It is also shown that the impact of the number of selected antennas lies in the array gain only. Furthermore, the GST/GSC scheme significantly improves the performance relative to single-antenna selection, and only incurs a negligible reduction in performance relative to all-antenna beamforming. Finally, the optimal relay location that minimises the SER is determined analytically. It is observed that the optimal relay location shifts towards one source when the number of selected or available antennas at the other source increases.

Optimal Power Allocation for Multiuser Secure Communication in Cooperative Relaying Networks

We consider a cooperative relaying network in which a source communicates with a group of users in the presence of one eavesdropper. We assume that there are no source-user links and the group of users receive only retransmitted signal from the relay. Whereas, the eavesdropper receives both the original and retransmitted signals. Under these assumptions, we exploit the user selection technique to enhance the secure performance. We first find the optimal power allocation strategy when the source has the full channel state information (CSI) of all links. We then evaluate the security level through: 1) ergodic secrecy rate and 2) secrecy outage probability when having only the statistical knowledge of CSIs.

Secure Cognitive Relay Network: Joint the Impact of Imperfect Spectrum Sensing and Outdated Feedback

In this paper, we consider cognitive relay networks with Nth best relay and beamforming schemes under the joint impact of imperfect spectrum sensing and outdated channel feedback. Specifically, we examine the secrecy performance by deriving the exact and asymptotic analytical expressions for the secrecy outage probability. Based on the analysis, we observe that these two types of channel impairments, i.e., imperfect spectrum sensing and outdated channel feedback, greatly affect the system performance. Particularly, the outdated channel feedback (i.e., the outdated coefficient

Modeling and Analysis of Interference for Diffusion-Based Nanoscale Networks with Spatially Distributed Transmitters

\rho\,<\,1

Secure Massive MIMO Relaying Systems in a Poisson Field of Eavesdroppers

ρ<1) reduces the secrecy outage diversity gain of the two schemes, i.e., Nth best relay and beamforming, to one regardless of the number of relays. Our proposed analysis provides a helpful guideline for security system designers to cope with the unpleasant channel impairments.

On the capacity and energy efficiency of non-coherent Rayleigh fading channels with additive Gaussian mixture noise

A cooperative network in which confidential messages are conveyed from a source to a legitimate destination with the help of decode-and-forward relays in the presence of a malicious eavesdropper is considered. Tight upper bounds on the ergodic secrecy rate are derived in the cases of i) cooperative beamforming and ii) multi-user selection. Further, a new concept of cooperative diversity gain, namely, adapted cooperative diversity gain (ACDG), is investigated. It is shown that the ACDG can be seen as an effective metric to evaluate the security level of a cooperative wireless network in the presence of eavesdroppers. Also, the ACDG obtained in the cooperative beamforming scenario is equal to the traditional cooperative diversity gain of traditional multiple-input single-output networks, while the ACDG obtained in the multiuser scenario is equal to that of traditional single-input multiple-output networks.