We consider a confidential communication system in which a source sends a confidential information to the destination in the presence of an eavesdropper. Multiple relays are used to provide cooperative diversity to the destination. The destination and the eavesdropper are equipped with multiple antennas while each relay and source are equipped with single antenna. We are interested to protect the transmitted information from eavesdropping and to find the effect of receive diversity on the secrecy capacity of the proposed model. We consider the maximal ratio combining (MRC) technique at the destination and derive the expression of combiner output signal-to-noise ratio (SNR) using optimum weighting vector so that the eavesdropper is unable to decode a single bit from the original massage. Finally, we derive the expression of optimum secrecy capacity in terms of the number of relays and the number of antennas at the destination. Our results show that the optimization of weighting vector at the receiver enhances secrecy capacity of a wiretap channel.
We consider a confidential communication system in which a source sends a confidential information to the destination in the presence of an eavesdropper. Multiple relays are used to provide cooperative diversity to the destination. The destination and the eavesdropper are equipped with multiple antennas while each relay and source are equipped with single antenna. We are interested to protect the transmitted information from eavesdropping and to find the effect of receive diversity on the secrecy capacity of the proposed model. We consider the maximal ratio combining (MRC) technique at the destination and derive the expression of combiner output signal-to-noise ratio (SNR) using optimum weighting vector so that the eavesdropper is unable to decode a single bit from the original massage. Finally, we derive the expression of optimum secrecy capacity in terms of the number of relays and the number of antennas at the destination. Our results show that the optimization of weighting vector at the receiver enhances secrecy capacity of a wiretap channel.
In this paper, a secured dual-hop confidential communication system is considered. In which, a source transmits secret information to the destination in the presence of an interferer and an eavesdropper. And, multiple relays provide cooperative diversity at the destination. The interferer, source and relays are equipped with single antenna whereas the destination and eavesdropper are equipped with multiple antennas. The maximum ratio combining (MRC) technique is used to get the best output SNR at the receiver. At the receiver, the expression of MRC combiner output SNR is derived using optimal weighting vector to protect the information from eavesdropping, so that the eavesdropper can't decipher the source message. Then, we derive the optimum secrecy capacity expression at the destination. The derived expressions and the numerical results show that there is an enhancement of secrecy capacity due to the strategy of optimization of the output SNR by weighting vector at the destination.
This paper is concerned with the study of confidential communication through independent and identically distributed (i.i.d.) and evenly correlated Rayleigh fading channels, where a single antenna transmitter communicates with the corresponding receiver in the presence of an eavesdropper. Both the receiver and eavesdropper are equipped with multiple antennas and employ diversity combining receptions such as maximal ratio combining (MRC) and selection combining (SC) diversities. In the presence of channel diversity, we derive the upper and lower bounds on the secrecy capacity with full channel state information (CSI) at the transmitter. The closed-form expression for the upper bound is also derived at high signal-to-noise ratio (SNR) regime. The analysis of upper bound with the diversity combining techniques tells how the channel diversity enhances secrecy capacity. Moreover, as a result of deriving the expression in a closed-form, it is insightful to see, how the channel parameters such as correlation coefficient and the ratio of main and eavesdropper channel gains that will be called average channel gain ratio (CGR) affect the secrecy capacity.
In this paper, a confidential communication scenario is considered through selection decode-and-forward cooperative relay networks over Rayleigh fading channel in which a source communicates with a destination via multiple relays. A best relay is selected using selection combining technique which communicates with the destination. An eavesdropper observes their communication and tries to decode confidential information. In this situation, an interest is given to ensure secure communication between the best relay and the destination so that eavesdropper is unable to decode any information from the main channel (i.e. channel between relay and destination). The performance of the proposed model is analyzed based on the closed-form analytical expressions of the ergodic secrecy capacity and the secure outage probability taking into account the distances of relays from the source, destination and the eavesdropper. Analytical results show that the additional diversity provided by the best relay situated in a strategic location significantly improves the secure outage performance of the selection decode-and-forward relay networks.
This paper presents a study on secure wireless multicasting using a Neyman-Pearson receiver in conjunction with the maximal ratio combining (MRC) diversity technique and opportunistic relaying. The MRC diversity technique effectively mitigates the impact of fading, while opportunistic relaying enhances cooperative communication by selecting the relay with the highest signal-to-noise ratio (SNR). The authors aim to safeguard the transmitted signal from eavesdropping, considering factors such as the number of relays, the number of receive and eavesdropper-side antennas, the number of multicast users, and the number of eavesdroppers. In this context, closed-form analytical expressions are derived for the probability of nonzero secrecy multicast capacity (PNSMC) and the secure outage probability for multicasting (SOPM) to ensure secrecy in the presence of multiple eavesdroppers. These mathematical models shed essential light on how the previously listed parameters affect things. Numerical results demonstrate that the security of the multicast network employing the Neyman-Pearson receiver, MRC diversity, and opportunistic relaying is significantly influenced by the number of relays, antennas on both the receiver and eavesdropper sides, multicast users, and eavesdroppers, particularly in low noise power regions of the eavesdropper channel.
In this paper, a source communicates to the destination with the cooperation of a relay, in the presence of an eavesdropper. All the links undergo Rayleigh fading and perfect decoding at the relays is not considered. The secrecy outage probability expression is evaluated for a decode-and-forward (DF) dual-hop cooperative relay network, both with and without the presence of direct source to eavesdropper transmission link. The performance of the maximal ratio combining (MRC) and selection combining (SC) diversity at the eavesdropper is investigated. Asymptotic and diversity gain analysis for both the single relay and multi-relay system is obtained, when average SNRs of source-relay and relay-destination links are balanced or unbalanced. We have shown that the increase in target secrecy rate and eavesdropper channel quality significantly affects the outage performance of the system. We have investigated the outage probability of optimal relay selection scheme, when either full instantaneous channel state information (ICSI) or statistical channel state information (SCSI) of all the links is available and have shown that there is improvement in the secrecy performance with the increase in the number of relays.
In this paper, the physical-layer security of a cooperative wireless system with multi-antenna full-duplex (FD) destination is examined. More specifically, we consider a cooperative transmission scenario in which a source communicates with a destination through a relay in the presence of an eavesdropper. In order to degrade the wiretap channel, the FD destination simultaneously transmits an interference signal towards the eavesdropper, while receiving information from the relay. A joint transmit and receive beamformer design is proposed to maximize the signal-to-interference-plus-noise ratio (SINR) at the destination, while guaranteeing that the SINR at the eavesdropper is below a certain threshold. We reformulate the optimization problem as a semidefinite relaxation problem in terms of a transmit beamforming matrix. To balance the performance and system complexity, we investigate suboptimum beamforming designs based on zero-forcing criterion. We derive exact closed-form expressions for the average secrecy rates of the proposed suboptimum designs. Our results reveal that optimum and suboptimum beamforming schemes along with friendly jamming significantly improve the secrecy performance. Moreover, simulation results demonstrate that the optimum scheme outperforms suboptimum schemes, especially in high transmit power regimes.