Pham Ngoc Son

Exact Outage Probability of Two-Way Decode-and-Forward Scheme with Opportunistic Relay Selection Under Physical Layer Security

The combination of cooperative communication and physical layer security is an effective approach to overcome the disadvantages of the fading environment as well as to increase the security capacity of the wireless network. In this paper, we propose a two-way decode-and-forward scheme with a relay selection method. In the proposed protocol, two source nodes communicate with each other with the help of intermediate relays under the eavesdropping of another wireless node, called the eavesdropper node. The best relay, which is chosen by the max–min strategy, uses digital network coding to enhance secure communication and spectrum use efficiency. The system performance is analyzed and evaluated in terms of the exact closed-form outage probability over Rayleigh fading channels. The Monte-Carlo simulation results are presented to verify the theoretical analysis. Finally, the proposed protocol is compared with the two-way protocol, which does not use digital network coding.

The underlay cooperative cognitive network with secure transmission

In this paper, we propose and analyze an underlay cooperative cognitive network with Physical Layer Security where a best relay is selected based on maximizing end-to-end secrecy capacity. The cooperative system performance is evaluated by an outage secrecy probability and is compared with the direct transmission protocol. Our simulation results show that system performance is improved when dse > dsd and the cognitive network is far enough from the primary user, where dsd and dse are the distances from a source to a destination and a source to an eavesdropper, respectively. In addition, the theoretical expressions match well with the simulation results.

Smart Power Allocation for Secrecy Transmission in Reciprocally Cooperative Spectrum Sharing

By cooperative spectrum sharing schemes, a primary network (PN) leases a part of the licensed band to a secondary network (SN). A secondary transmitter (ST) acts as a relay for the primary transmitter (PT) to improve the end-to-end link quality of the PN, and as a reward, the ST gets the opportunity to transmit its own data by superposition coding. In this paper, a new cooperative spectrum sharing (CSS) scheme taking into account malicious eavesdropping (wiretapping) by a PN is proposed. In such scheme, licensed band is a decoy to an SN to wiretap the secondary transmission. Thus, secrecy in secondary transmission becomes critical to the SN. To get achievable secrecy (data) rate in secondary transmission and to fulfill the duty as a relay for primary transmission, the SN looks for a smart power-allocation (SPA) parameter that satisfies both goals. SPA parameter αsmart provides the target secrecy data rate, and the achieved data rate at the PN is greater than or equal to the data rate obtained by the direct transmission (DT). Considering a Rayleigh block-fading channel, the SPA parameter is evaluated for each secondary transmission. Details on the evaluation of the SPA parameter are presented, and theoretical outage probabilities of the PN and the SN are derived and validated by simulations.

An Integration of Source and Jammer for a Decode-and-Forward Two-way Scheme Under Physical Layer Security

In this paper, we propose and analyze the integration of source and jammer for a decode-and-forward two-way scheme under physical layer security where the source nodes not only transmit data signals, but also transmit jamming signals to degrade the quality of eavesdropping links, and a selected relay forwards the combined data signals using an XOR operation. In this proposed protocol, the best relay is chosen by the maximum end-to-end achievable secrecy rate, and the secrecy system performance is evaluated by the exact and asymptotic secrecy outage probability over flat and block Rayleigh fading channels. The Monte-Carlo results are presented to verify the theoretical analysis.

Exact Outage Probability of a Decode-and-Forward Scheme with Best Relay Selection Under Physical Layer Security

As demand for highly reliable data transmission in wireless networks has increased rapidly, cooperative communication technology has attracted a great deal of attention. In cooperative communication, some nodes, called eavesdroppers, illegally receive information that is intended for other communication links at the physical layer because of the broadcast characteristics of the wireless environment. Hence, Physical Layer Security is proposed to secure the communication link between two nodes against access by the eavesdroppers. In this paper, we propose and analyze the performance of decode-and-forward schemes with the best relay selection under Physical Layer Security with two operation protocols: first, only cooperative communication, and second, a combination of direct transmission and cooperative communication (the incremental protocol). In these schemes, a source transmits data to a destination with the assistance of relays, and the source-destination link is eavesdropped by one other node. The best relay is chosen in these proposals based on the maximum Signal-to-Noise ratio from the relays to the destination, and satisfies the secure communication conditions. The performance of each system is evaluated by the exact outage probability of the data rate over Rayleigh fading channels. Monte-Carlo results are presented to verify the theoretical analysis and are compared with a direct transmission scheme under Physical Layer Security and compared with each other.

Improvement of the two‐way decode‐and‐forward scheme by energy harvesting and digital network coding relay

In this paper, we propose a two-way decode-and-forward scheme with an energy-harvesting relay in which the relay harvests energy from radio-frequency signals of source nodes by applying a power-splitting receiver and broadcasts coded signals using digital network coding (NCTW protocol). The system performance of the proposed NCTW protocol is compared with that of a conventional two-way decode-and-forward scheme without digital network coding (CTW protocol) and a two-way amplify-and-forward scheme with analogue network coding (TWAF protocol). Exact outage probability expressions are obtained to the NCTW and CTW protocols, whereas a lower bound expression is used to evaluate the TWAF protocol. The theoretical analyses are verified by Monte Carlo simulations. Evaluations show that (1) the proposed NCTW protocol outperforms the CTW and TWAF protocols; (2) the NCTW, CTW and TWAF protocols achieve the best performance when the power-splitting ratios converge to optimal values; (3) at the midpoint of two source nodes, the sum system performance of the NCTW and CTW protocols is the best, whereas that of the TWAF protocol is the worst; and finally, (4) the theoretical analyses of the NCTW and CTW protocols match well with the Monte Carlo simulation results, and the lower bound expression of the TWAF protocol converges to the exact results at the high signal-to-noise ratio. Copyright

Exact Outage Probability of Cooperative Secrecy Transmission: Impact of Unavailable Relays

The impact of unavailable relays is a serious issue in cooperative communication schemes, where the operation state of relays affects optimal relay selection. In addition, secure signal transmission is an interesting approach to prevent the wiretapping actions of eavesdropper nodes in a wireless environment. In this paper, we propose two cooperative secrecy transmission schemes: a secrecy decode-and-forward protocol and a hybrid of direct secrecy and cooperative secrecy transmission schemes to enhance the spectrum utilization efficiency. In the proposed schemes, a source transmits data signals to a destination with the assistance of relays. At the same time, these data signals are eavesdropped by another node. The best relays are successfully selected in a safe manner based on both decoding from a source to a destination and the available state of cooperative relays. The secrecy performance of each scheme is analyzed and evaluated by the exact outage probability over Rayleigh fading channels. Monte Carlo simulations were performed to verify the theoretical analysis. Finally, a discussion and comparison of the cooperative secrecy transmission schemes and the direct secrecy transmission approach are presented.

Performance Analysis of Decode-and-Forward Scheme with Relay Ordering for Secondary Spectrum Access

The communication efficiency of primary networks in cognitive radio depends on wireless environments, such as obstacles (e.g. buildings), distances between transmitter and receiver, and limited transmit power. A cooperative model between primary and secondary networks has the potential to overcome these problems. In this paper, we propose and analyze the performance of a decode-and-forward scheme with relay ordering for secondary spectrum access. In this scheme, a primary transmitter communicates with a primary receiver with the help of two secondary transmitters. Each secondary transmitter relays primary signals from the primary transmitter to primary receiver, and follows an optimal order to ensure the best communication capacity of the primary network and to find opportunities to transmit its own signals. The performance of primary and secondary networks is evaluated by theoretical analysis in terms of outage probability. Monte Carlo simulations are presented to verify the theoretical analysis and to compare the performance of the proposed protocol with that of a direct transmission protocol and a decode-and-forward protocol with a relay selection scheme.

Physical layer security over Dual-Hop Asymmetric Fading Channels

In this paper, the line-of sight and non line-of sight characteristics of a received signal are exploited to analyze the secrecy performance of the decode-and-forward scheme over Dual-Hop Asymmetric Fading Channels. In this scheme, the first hop from a source to relays is subject to Rician fading, whereas the second hop from relays to a destination experience Nakagami-m fading. The best relay is chosen to help the source to transmit data signals to the destination based on achievable secrecy rate (ASR) following criterions as: best source-relay, best relay-destination and best end-to-end. The secrecy performance is exactly evaluated by the secrecy outage probability of the ASR. The Monte-Carlo results are presented to verify the theoretical analysis.

Performance analysis of a decode-and-forward scheme under physical layer security over Rician fading channel

In this paper, we propose and evaluate the performance of the decode-and-forward scheme under physical layer security over Rician fading channel. The best relay is chosen to help the source to transmit data signals to the destination based on achievable secrecy rate (ASR) following criterions as: maximum first-single-hop, maximum second-single-hop and maximum dual-hop. The system performance is exactly evaluated by the outage probability of the ASR. The Monte-Carlo results are presented to verify the theoretical analysis.