In wireless communication, physical layer security is widely used for secure communication between the transmitter and the receiver. In this paper, the secrecy performance of two cooperative schemes, decode-and-forward (DF) and amplify-and-forward (AF) relays is investigated in a single hop wireless relaying system. The achievable secrecy rate is investigated with these two types of relays under the constraint of total power transmitted. In the given jamming relay network, the relay transmits jamming signal while receiving data signal from the source. It is indicated by the resulting analysis that the AF relays have better secrecy rate as compared to the DF relays in the given condition. The secrecy rate of the AF relay is higher than that of the DF relay by 71.88% at a distance of 70 m between the relay and the eavesdropper in this jamming relay network.
In wireless communication, physical layer security is widely used for secure communication between the transmitter and the receiver. In this paper, the secrecy performance of two cooperative schemes, decode-and-forward (DF) and amplify-and-forward (AF) relays is investigated in a single hop wireless relaying system. The achievable secrecy rate is investigated with these two types of relays under the constraint of total power transmitted. In the given jamming relay network, the relay transmits jamming signal while receiving data signal from the source. It is indicated by the resulting analysis that the AF relays have better secrecy rate as compared to the DF relays in the given condition. The secrecy rate of the AF relay is higher than that of the DF relay by 71.88% at a distance of 70 m between the relay and the eavesdropper in this jamming relay network.
This paper investigates the secrecy performance of single hop relaying network with Energy Harvesting (EH) and also shows that the system with EH outperforms the conventional system in terms of secrecy rate and energy efficiency. In the proposed system, the source transmits the information signal to the destination via a relay in the presence of an eavesdropper and the source and relay utilizes time switching EH technique to obtain power from a power beacon. This paper compares the secrecy rate of two cooperative schemes: decode-and-forward (DF), and amplify-and-forward (AF) for both proposed system with EH and the conventional system. The system with EH provides higher secrecy rate than that of the conventional system by 30.47 % for DF cooperative scheme and by 23.63 % for AF relay at a distance of 40 m between the eavesdropper and the relay. The resulting analysis also shows that the secrecy rate of the AF relay is higher than that of the DF relay in both considered system with EH and conventional system.
Physical (PHY) layer security approaches for wireless communications can prevent eavesdropping without upper layer data encryption. However, they are hampered by wireless channel conditions: absent feedback, they are typically feasible only when the source-destination channel is better than the source-eavesdropper channel. Node cooperation is a means to overcome this challenge and improve the performance of secure wireless communications. This paper addresses secure communications of one source-destination pair with the help of multiple cooperating relays in the presence of one or more eavesdroppers. Three cooperative schemes are considered: decode-and-forward (DF), amplify-and-forward (AF), and cooperative jamming (CJ). For these schemes, the relays transmit a weighted version of a reencoded noise-free message signal (for DF), a received noisy source signal (for AF), or a common jamming signal (for CJ). Novel system designs are proposed, consisting of the determination of relay weights and the allocation of transmit power, that maximize the achievable secrecy rate subject to a transmit power constraint, or, minimize the transmit power subject to a secrecy rate constraint. For DF in the presence of one eavesdropper, closed-form optimal solutions are derived for the relay weights. For other problems, since the optimal relay weights are difficult to obtain, several criteria are considered leading to suboptimal but simple solutions, i.e., the complete nulling of the message signals at all eavesdroppers (for DF and AF), or the complete nulling of jamming signal at the destination (for CJ). Based on the designed relay weights, for DF in the presence of multiple eavesdroppers, and for CJ in the presence of one eavesdropper, the optimal power allocation is obtained in closed-form; in all other cases the optimal power allocation is obtained via iterative algorithms. Numerical evaluation of the obtained secrecy rate and transmit power results show that the proposed design can significantly improve the performance of secure wireless communications.
In this article, we investigated the secrecy performance of a three-hop relay network system with Power Splitting (PS) and Energy Harvesting (EH). In the presence of one eavesdropper, a signal is transferred from source to destination with the help of a relay. The source signal transmits in full-duplex (FD) mood, jamming the relay transfer signals to the destination. The relay and source employ Time Switching (TS) and Energy Harvesting (EH) techniques to obtain the power from the power beacon. In this study, we compared the Secrecy Rate of two Cooperative Schemes, Amplify and Forward (AF) and Decode and Forward (DF), for both designed systems with the established EH and PS system. The Secrecy Rate was improved by 50.5% in the AF scheme and by 44.2% in the DF scheme between the relay and eavesdropper at 40 m apart for the proposed system in EH and PS. This simulation was performed using the Monto Carlo method in MATLAB.
We consider a cooperative wireless network in the presence of one or more eavesdroppers, and exploit node cooperation for achieving physical (PHY) layer based security. Two different cooperation schemes are considered. In the first scheme, cooperating nodes retransmit a weighted version of the source signal in a decode-and-forward (DF) fashion. In the second scheme, referred to as cooperative jamming (CJ), while the source is transmitting, cooperating nodes transmit weighted noise to confound the eavesdropper. We investigate two objectives: i) maximization of the achievable secrecy rate subject to a total power constraint and ii) minimization of the total power transmit power under a secrecy rate constraint. For the first design objective, we obtain the exact solution for the DF scheme for the case of a single or multiple eavasdroppers, while for the CJ scheme with a single eavesdropper we reduce the multivariate problem to a problem of one variable. For the second design objective, existing work introduces additional constraints in order to reduce the degree of difficulty, thus resulting in suboptimal solutions. Our work raises those constraints, and obtains either an analytical solution for the DF scheme with a single eavesdropper, or reduces the multivariate problem to a problem of one variable for the CJ scheme with a single eavesdropper. Numerical results are presented to illustrate the proposed results and compare them to existing work.
In this paper, we consider secure communications of one source-destination pair in wireless multi-hop decode-and-forward (DF) relay networks. In the presence of an eavesdropper, we derive an optimal power allocation strategy to maximize achievable secrecy rates under an overall transmit power constraint assuming that a single relay is located at each individual hop. We demonstrate that the optimal power allocation is obtained when the overall power constraint and the DF-relaying constraints necessary to guarantee that each DF relay correctly decodes the information signals hold with equality, which rely on channel conditions between the source, relays, and destination. The channel conditions for the eavesdropper are shown to only influence relays that may be inactive for secrecy rate maximization. We also consider multiple cooperative relays at each hop to perform cooperative beamforming in the presence of multiple eavesdroppers. To improve the secrecy rate in multi-hop relay networks, which include more than two hops, we propose an iterative cooperative beamformer design and transmit power allocation scheme with relay selection. Numerical results are presented to investigate the secrecy capacity obtained by the optimal power allocation in multi-hop DF relay networks and to confirm the secrecy rate enhancement of the proposed cooperative beamforming scheme.
In a cooperative wireless network, we exploited node cooperation for achieving physical layer based security. In this paper, the case of one source-destination pair with the help of multiple cooperating nodes(relay nodes and jamming nodes) in the presence of one eavesdropper was considered to improve the performance of secure wireless communications. A novel cooperative scheme joint decode-and-forward and cooperative jamming(JDFCJ) was proposed. In this scheme, the relay nodes transmit a weighted version of the source signals and the jamming nodes just transmit a common weighted jamming signal to confound the eavesdropper. The novel system design is proposed to minimize the transmit power subject to a secrecy rate constraint. For JDFCJ, the optimal power allocation is obtained in closed-form in the condition of the complete nulling of jamming signals at the destination. The numerical evaluation of the transmit power results shows that the proposed scheme can significantly improve the performance of secure wireless communications, as compared to the DF scheme.