Sang Quang Nguyen

Outage Performance and Diversity Analysis of Cognitive Triple-Hop Cluster-Based Networks Under Interference Constraint

In this paper, a full diversity for a triple-hop underlay cognitive network is investigated. In secondary network, multiple decode-and-forward (DF) relays located in two clusters help a source forwarding data to a destination under interference constraint with a primary user. We analyze and compare the outage performance and diversity order of two proposed protocols of the three hops model: the hop between a source node and multiple relays in the first cluster, the hop between the first and second clusters, and the hop between the second cluster and a destination node. One optimal relay (or a best relay) in each cluster is chosen by the selection strategies of two proposed protocols, which take the role of decoding and forwarding the message from the previous node to the next node. To be more specific, the optimal relay in the first cluster decodes the source signal and forward the re-encoded one toward the best relay in second cluster; next, the best relay in this cluster DFs the received signal to the destination node. Finally, we determine the approximate expressions of the end-to-end outage probability and obtain the diversity order for each protocol when the value of the Gaussian noise is small.

Performance analysis of energy-harvesting relay selection systems with multiple antennas in presence of transmit hardware impairments

In this paper, we consider a decoded-and-forward (DF) energy-harvesting system with multiple antennas in the presence of transmit hardware impairments. The relays are energy-constrained nodes that collect energy from the source signals using time-switching architecture. Two partial relay selection (PRS) schemes that are PRS-1 and PRS-2 are employed for simplifying the relay-selection complexity. In particular, for the PRS-1 scheme, the best relay that assists the source-to-destination communication is selected based on the first-hop channel-state-information (CSI) whereas for the PRS-2 scheme, the best relay is selected based on the second-hop CSI. To evaluate the effects of hardware impairments on system performance, the analytical expressions for outage probability and throughput are derived. Monte Carlo simulation and insightful discussion are provided.

Outage Probability Analysis in Dual-Hop Vehicular Networks with the Assistance of Multiple Access Points and Vehicle Nodes

Vehicular networks represent an interesting research field that encompasses connections between vehicles or connections between a vehicle and an infrastructure. In this paper, we consider dual-hop transmission using cooperative communication in vehicular networks. In our system model, multiple intermediate access points and vehicle nodes are willing to help the source vehicle forward data to the destination vehicle. From these intermediate nodes, we choose an optimal node acting as a relay using three proposed protocols. We consider the channel between a vehicle terminal and an access point node as a Rayleigh fading channel, and the channel between two vehicles as a double Rayleigh fading channel. We derive exact expressions of the end-to-end outage probability for each of the three protocols, which are then verified by Monte-Carlo simulations.

Generalized diversity combining of energy harvesting multiple antenna relay networks: outage and throughput performance analysis

In this paper, the generalized diversity combining of an energy constrained multiple antenna decode-and-forward relay network is considered. Using power splitting and time switching architectures in consort with diversity combining at the relay, six protocols are proposed, i.e., power splitting with selection combining (PSSC), power splitting with maximum ratio combining (PSMRC), power splitting with generalized selection combining (PSGSC), time switching with selection combining (TSSC), time switching with maximum ratio combining (TSMRC), and time switching with generalized selection combining (TSGSC). The outage probability and throughput performance of each protocol is analyzed by first developing the closed form analytical expressions and then verifying these through the Monte Carlo simulation method. Simulation results show that system performance improves both with increasing the number of antennas and decreasing the distance between the source and relay. The TSSC/TSMRC/TSGSC protocols yield better outage performance whereas the PSSC/PSMRC/PSGSC protocols achieve relatively higher throughput performance. Finally, the effects of power splitting ratio, energy harvesting time ratio, energy conversion efficiency, sample down conversion noise, and the target signal-to-noise ratio on system performance are analyzed and presented.

Exact outage analysis of the effect of co-channel interference on secured multi-hop relaying networks

ABSTRACT In this article, the presence of multi-hop relaying, eavesdropper and co-channel interference (CCI) in the same system model is investigated. Specifically, the effect of CCI on a secured multi-hop relaying network is studied, in which the source communicates with the destination via multi-relay-hopping under the presence of an eavesdropper and CCI at each node. The optimal relay at each cluster is selected to help forward the message from the source to the destination. We apply two relay selection approaches to such a system model, i.e. the optimal relay is chosen based on (1) the maximum channel gain from the transmitter to all relays in the desired cluster and (2) the minimum channel gain from the eavesdropper to all relays in each cluster. For the performance evaluation and comparison, we derived the exact closed form of the secrecy outage probability of the two approaches. That analysis is verified by Monte Carlo simulation. Finally, the effects of the number of hops, the transmit power at the source, relays and the external sources, the distance between the external sources and each node in the system, and the location of the eavesdropper are presented and discussed.

Secrecy enhancement in two-hop DF relaying system under hardware impairment

ABSTRACT In this paper, we investigate joint jammer selection and network coding for secrecy enhancement under transceiver hardware impairment. We propose two protocols of joint jammer selection and network coding (SCCJ-OJS and SCCJ-MiJS) to improve secrecy outage and throughput performance compared with a protocol without cooperative jamming (SCC). For performance evaluation, we derive exact closed-form expressions for the secrecy outage probability (SOP) and throughput performance of the three protocols. Our analysis is substantiated via Monte Carlo simulation. The results show that the SCC protocol is nearly in an outage state when the eavesdroppers are close to the source and/or relays, while the SCCJ-OJS and SCCJ-MiJS protocols still improve the performance compared with the SCC protocol in this strict case. In addition, transceiver hardware impairments can degrade the eavesdropping channel: the performance of the SCC protocol increases linearly with hardware impairment level, whereas SCCJ-OJS and SCCJ-MiJS protocol performance is enhanced at a low level and experience a minor decrease at a high level of hardware impairment. Finally, the theoretical results match the simulation results well.

Outage Performance of a Two-branch Cooperative Energy-constrained Relaying Network with Selection Combining at Destination

In this paper, we investigate two-branch cooperative DF relaying networks with selection combining at the destination. Two intermediate relay-clusters (a conventional relay cluster and an energy-constrained relay cluster) are utilized to aid the communication between the source and the destination. We study two cases: direct link (DR) and no direct link (NDR) between the source and the destination. In each case, we consider two relay selection schemes: best sourceâĂŞrelay channel gain (BSR) and random relay selection (RAN). Thus, we have 4 protocols: DR-BSR, DR-RAN, NDR-BSR, and NDR-RAN. For the performance evaluation, we derive a closed-form expression for the outage probability of each of the four protocols. Our analysis is substantiated via a Monte Carlo simulation. As expected, the results show that the DR case outperforms the NDR case, and the BSR scheme outperforms the RAN scheme. The outage performances of the protocols are evaluated based on the system parameters, including the transmit power, the number of relays in each cluster, the energy harvesting efficiency, the position of the two clusters, and the target rate. The outage performance of the system is improved when the transmit power increases, the energy harvesting efficiency increases, the distance between the two clusters and the source and destination decreases, or the target rate decreases. We found good matches between the theoretical and Monte Carlo simulation results, verifying our mathematical analysis.

Exact Outage Probability Analysis of a Dual-Hop Cognitive Relaying Network Under the Overhearing of an Active Eavesdropper

In this paper, we study the secure communication of dual-hop cognitive relaying networks. An eavesdropper can combine two received signals from two hops by using the maximum ratio combining technique. The data transmission from the secondary source to the secondary destination is assisted by the best decode-and-forward relay, which is selected from four relay selection schemes. The first scheme, MaSR, is based on the maximum channel gain from the source to the relays. In the second scheme, MaRD, the best relay is selected on the basis of the maximum channel gain from the relays to the destination. In the third scheme, MiRE, the gain to the eavesdroppers is instead minimized. Finally, optimal relay selection is considered as the fourth scheme. For these four schemes, we study the system security performance by deriving the exact analytical secrecy outage probability. These analytical expressions are then verified by comparing them with the results of Monte Carlo simulations. Herein, we evaluate and discuss the outage performance of the schemes while varying important system parameters: the number and locations of the relay nodes, primary user node, and eavesdropper; the transmit power threshold; and the target secure rate.

Throughput analysis of dual-hop relaying energy harvesting network with TAS/MRC

In this paper, a dual-hop time-switching (TS) energy-harvesting scheme is investigated. The source and destination are multiple-antenna devices, while the relay is an energy-constrained single-antenna node that harvests RF energy from the source and assists the source-to-destination transmission. Transmit antenna selection/maximal ratio combining is applied to exploit diversity gain in both energy-harvesting phase and information-transmitting phase. In particular, we evaluate the scheme on two criteria: outage probability (Pout) and throughput (τ). The closed-form expressions of Pout and τ are derived and verified by the Monte-Carlo simulation. Our results show that the implementation of multiple antennas achieves significant improvement on the system performance.

Combining Binary Jamming and Network Coding to Improve Outage Performance in Two-Way Relaying Networks under Physical Layer Security

By generating a jamming message at the jammer node, a system can reduce wiretapping in the physical layer because this message can refuse the illegal eavesdropper node. The network coding technique of operating an XOR between two binary messages improves the performance. In this paper, we propose three protocols that use network coding at the two source nodes and/or the binary jamming technique at a relay in the two-way relaying network under physical layer security, compared to a conventional secrecy transmission protocol. The main idea to improve the system performance is that, if the data is transmitted securely, the next transmission time slots using the digital network coding will not consider the presence of the eavesdropper node, because the eavesdropper node cannot obtain the data. The system performance is analyzed and evaluated in terms of the exact closed-form outage probability over Rayleigh fading channels. The simulation results using a Monte-Carlo simulation are in complete agreement with the theoretical results.