In this paper, we propose efficient power allocation techniques using both convex optimization (using Lagrange multiplier method) and a soft evolutionary approach (using Differential Evolution (DE) algorithm) to optimize both the relay and jammer powers in addition to an increase in the system performance in terms of secrecy rate. Here, we consider a cooperative wireless network with control jamming comprising of a source-destination pair with a set of relay nodes in the presence of single and multiple eavesdroppers. Optimal relay node is selected based on the SNR received at each relay, which transmits the data to the destination using decode and forward strategy. Amongst the remaining nodes, selection of jammer is done based on the SNR value of the relay to eavesdropper link. The proposed power allocation schemes are compared with equal power allocation policy for using the Monte-Carlo simulation study and these schemes are found to be superior in terms of average secrecy rate.
In this paper, we propose efficient power allocation techniques using both convex optimization (using Lagrange multiplier method) and a soft evolutionary approach (using Differential Evolution (DE) algorithm) to optimize both the relay and jammer powers in addition to an increase in the system performance in terms of secrecy rate. Here, we consider a cooperative wireless network with control jamming comprising of a source-destination pair with a set of relay nodes in the presence of single and multiple eavesdroppers. Optimal relay node is selected based on the SNR received at each relay, which transmits the data to the destination using decode and forward strategy. Amongst the remaining nodes, selection of jammer is done based on the SNR value of the relay to eavesdropper link. The proposed power allocation schemes are compared with equal power allocation policy for using the Monte-Carlo simulation study and these schemes are found to be superior in terms of average secrecy rate.
In this paper, we examine the physical layer security for cooperative wireless networks with multiple intermediate nodes, where the decode-and-forward protocol is considered. We propose a new joint relay and jammer selection (JRJS) scheme for protecting wireless communications against eavesdropping, where an intermediate node is selected as the relay for the sake of forwarding the source signal to the destination and meanwhile, the remaining intermediate nodes are employed to act as friendly jammers, which broadcast the artificial noise for disturbing the eavesdropper. We further investigate the power allocation among the source, relay and friendly jammers for maximizing the secrecy rate of proposed JRJS scheme, and derive a closed-form sub-optimal solution. Specifically, all the intermediate nodes, which successfully decode the source signal, are considered as relay candidates. For each candidate, we derive the sub-optimal closed-form power allocation solution and obtain the secrecy rate result of the corresponding JRJS scheme. Then, the candidate, which is capable of achieving the highest secrecy rate, is selected as the relay. Two assumptions about the channel state information (CSI), namely the full CSI (FCSI) and partial CSI (PCSI), are considered. Simulation results show that the proposed JRJS scheme outperforms the conventional pure relay selection, pure jamming, and generalized singular-value-decomposition-based beamforming schemes in terms of secrecy rate. Additionally, the proposed FCSI-based power allocation and PCSI-based power allocation schemes both achieve higher secrecy rates than the equal power allocation scheme.
In this paper, we examine the physical layer security for cooperative wireless networks with multiple intermediate nodes, where the decode-and-forward (DF) protocol is considered. We propose a new joint cooperative beamforming and jamming (JCBJ) scheme to protect wireless communication against eavesdropping, where the intermediate nodes which successfully decode the source signal are selected as the relays for simultaneously forwarding the source signal by employing a weight vector, and meanwhile, the others are used to act as the friendly jammers for broadcasting artificial noise to disturb the eavesdropper. We further investigate the optimal power allocation among the source, relays and friendly jammers for maximizing the secrecy rate of the proposed JCBJ scheme and derive a closed-form sub-optimal solution. Simulation results show that the proposed JCBJ scheme achieves obviously higher secrecy rate than the conventional generalized singular-value-decomposition (GSVD) based beamforming and pure jamming schemes. Additionally, the proposed optimal power allocation scheme performs much better than the equal power allocation scheme in terms of secrecy rate.
In this paper, we propose a new joint relay and jammer selection (JRJS) scheme to enhance the physical layer security for cooperative wireless networks with multiple intermediate nodes, where the decode-and-forward (DF) protocol is considered. In the proposed JRJS scheme, an intermediate node is selected as the relay for data transmission, while the others are used to act as friendly jammers for disrupting the eavesdropper by broadcasting artificial noise. We focus on the power allocation between the relay and jammers to maximize the secrecy rate of proposed JRJS scheme under a total transmit power constraint, and derive a closed-form optimal power allocation solution. For the purpose of comparision, the conventional pure relay selection and pure jammer selection schemes are considered as benchmark schemes. Simulation results show the advantage of the proposed JRJS scheme over conventional pure relay selection and pure jammer selection methods in terms of secrecy rate. Additionally, the derived optimal power allocation solution leads to a significantly higher secrecy rate than the equal power allocation scheme.
In this paper, the security of two-phase relaying system with multiple intermediate nodes in the presence of a malicious eavesdropper is investigated. To enhance the secrecy, a joint cooperative beamforming and jamming combined with relay and jammer selection is proposed. First, the source broadcasts its signal to the relays that are located close to source in a cluster, i.e., the source node uses a small amount of power to broadcast its message locally to other nodes of the cluster, while destination and the eavesdropper are located outside this cluster. In the second phase, two relays transmit re-encoded signal with optimal beamforming such that the secrecy rate is maximized. Simultaneously, two other intermediate nodes (which act as friendly jammers) transmit random jamming signals to degrade the eavesdropper’s channel. Our goal in this paper is to maximize the secrecy rate by applying different methods such as cooperative beamforming, cooperative jamming and relay and jammer selection. To avoid operational complexity, we consider the minimum number of intermediate nodes needed for relaying and jamming without losing the performance, i.e., achieving a non-zero secrecy rate. Cooperative beamforming with multiple relays demands high amount of information exchange and therefore increases the operational complexity. Thus, we aim to reduce the number of relays which take part in cooperative beamforming. Limiting the number of relays may have a bad effect on the coding gain which we compensate it with a proposed selection gain scheme. Numerical results demonstrate the advantage of our proposed scheme compared to the scheme with no cooperative jamming. The main contribution of this work is combining cooperative beamforming and jamming with relay and jammer selection to enhance the physical layer security.
This paper proposes a joint cooperative relaying and jamming scheme based on distributed beamforming to enhance the secrecy rate of a wireless channel in the presence of an eavesdropper. Specifically, we consider the scenario that a source node transmits messages to a destination with the help of multiple cooperative relays, where a relay might be compromised to become an eavesdropper as an inside attacker. Our joint relaying and jamming approach is to assign some relay nodes to act as jammers to interfere the eavesdropper, while the remaining ones continue relaying information to the destination. We propose a protocol to implement the joint cooperative relaying and jamming. Our protocol further considers the particular challenge brought by the inside attacker: it may know the jamming signal and can use it to remove the interference from the jammers. The issue of phase and frequency synchronization in the distributed beamforming is also taken into account. A mixed integer programming problem is formulated to maximize the secrecy rate with the proposed joint relaying and jamming, by which the optimal role assignment to a relay and the associated optimal power assignment can be solved. Numerical results are presented to demonstrate the efficiency of the proposed joint relaying and jamming in improving the secrecy rate, with comparison to existing approaches.
To improve physical (PHY) layer security of a wireless relay system in the presence of an eavesdropper, a two-phase cooperative relaying scheme is investigated in this paper. In phase I, the source transmits confidential message, simultaneously, it cooperates with the friendly jammers and destination to create jamming signal at the eavesdropper without affecting the forwarding relay which is preselected. In phase II, the forwarding relay retransmits the decoded signal, meanwhile, the particular relay cooperates with the friendly jammers to create jamming signal at the eavesdropper without affecting the destination. We focus on the investigation of optimal power allocation for maximizing achievable secrecy rate subject to a total power constraint. Optimal relay selection and suboptimal relay selection schemes are also proposed. It is shown that as the number of relays increases, both secrecy rate and the performance of suboptimal relay selection scheme improve significantly. Numerical results are presented to validate the derived analytical results and compare them to existing work.