This paper proposes a new joint cooperative beamforming and jamming (JCBJ) scheme for improving the physical layer security of decode-and-forward wireless networks where a source node transmits to its destination with the aid of multiple intermediate nodes in the presence of an eavesdropper. In the proposed JCBJ scheme, we select the intermediate nodes succeeding in source decoding as the relays to forward the source transmission simultaneously by employing a beamforming weight vector, and meanwhile, use the remaining ones as the friendly jammers to disturb the eavesdropper by sending artificial noise. In order to achieve the secrecy rate maximum, we further study on the power allocation among the source, relays, and jammers under two assumptions of the wiretap link's channel state information. We derive the closed-form optimal solutions by first allocating the transmit power at the source within different ranges to consider all the possible relay selection schemes in which different numbers of relays are employed, and then transforming the multivariable power allocation problem to a set of single-variable optimization subproblems. Our numerical results show the superiority of the proposed JCBJ scheme and the proposed power allocation strategies.
This paper proposes a new joint cooperative beamforming and jamming (JCBJ) scheme for improving the physical layer security of decode-and-forward wireless networks where a source node transmits to its destination with the aid of multiple intermediate nodes in the presence of an eavesdropper. In the proposed JCBJ scheme, we select the intermediate nodes succeeding in source decoding as the relays to forward the source transmission simultaneously by employing a beamforming weight vector, and meanwhile, use the remaining ones as the friendly jammers to disturb the eavesdropper by sending artificial noise. In order to achieve the secrecy rate maximum, we further study on the power allocation among the source, relays, and jammers under two assumptions of the wiretap link's channel state information. We derive the closed-form optimal solutions by first allocating the transmit power at the source within different ranges to consider all the possible relay selection schemes in which different numbers of relays are employed, and then transforming the multivariable power allocation problem to a set of single-variable optimization subproblems. Our numerical results show the superiority of the proposed JCBJ scheme and the proposed power allocation strategies.
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 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 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.
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.
Securing the wireless transmissions in the physical layer is a new perspective of security. In a wireless relay system, cooperative beamforming and jamming are two efficient schemes to improve the physical-layer security in the presence of passive eavesdroppers. However, in most works these two techniques are used in phase II of the cooperative transmission, which leaves the phase I out of protection. In this paper, we propose a joint cooperative beamforming and jamming scheme to enhance the security of a cooperative relay network, where a part of intermediate nodes adopt distributed beamforming while others jam the eavesdropper, simultaneously, such that both phases are secured. Since the instantaneous channel state information (CSI) of the eavesdropper may not be known, we propose a cooperative artificial noise transmission based secrecy strategy, subjected to the individual power constraint of each node. The beamformer weights and power allocation can be obtained by solving a second-order convex cone programming (SOCP) together with a linear programming problem. Simulations show the joint scheme greatly improves the security.