Cooperative system is a tendency for future communications because of its spatial diversity to improve the system performance. However, the security is a critical issue in the wireless application with a highly private request. Although the encryption schemes have been proposed to approach the secure purpose, those schemes need a lot of computing resource. It is not practical for the applications with limited computing ability, such as IoT. According to Shannon theory of perfect secrecy, the security could be implemented on the physical layer. Based on the positive secrecy rate, the evaluation of security, secure communication could be practical. This work concentrates on the theoretical solution to the secrecy rate in the AF mode cooperative communication system. Also, the numerical results with the proposed methodology are given. It shows the effects of eavesdropper could not affect the secure communication if the number of the eavesdropper is less than that of relays in the system. The appropriate relay assignment benefits the secure communication.
Cooperative system is a tendency for future communications because of its spatial diversity to improve the system performance. However, the security is a critical issue in the wireless application with a highly private request. Although the encryption schemes have been proposed to approach the secure purpose, those schemes need a lot of computing resource. It is not practical for the applications with limited computing ability, such as IoT. According to Shannon theory of perfect secrecy, the security could be implemented on the physical layer. Based on the positive secrecy rate, the evaluation of security, secure communication could be practical. This work concentrates on the theoretical solution to the secrecy rate in the AF mode cooperative communication system. Also, the numerical results with the proposed methodology are given. It shows the effects of eavesdropper could not affect the secure communication if the number of the eavesdropper is less than that of relays in the system. The appropriate relay assignment benefits the secure communication.
With the assistance of relays, cooperative communication provides the benefits of spatial diversity to improves the system performance. It could be prospective for the application of wireless networks. The issue of security is highly requested for personal privacy in the internet. With applying this cooperative system to internet service, security is critically requested. Usually, in the higher layer networks, it adopts an encryption to approach the security request. However, a complex encryption spends a lot of computer resource. It is not practical for Internet of things (IoT) application which has a limited computing resource. Shannon perfect secrecy illustrates the secure communication could be implemented on the physical layer. Assuming the relays in the system is the eavesdroppers, this paper provides the secrecy analysis for the cooperative system and gives a theoretical solution. With an appropriate assignment of relay, the results show that the cooperative system could provide a secure communication if the number of available relays is larger than that of eavesdroppers. A proper choosing the relays to transmit the information could be the important issue in the cooperative communication system.
Due to the character of low cost and easily to implemented, the cooperative communication is the future tendency. Three fundamental mode, Amplify-and-Forward (AF) mode, Decode-and-Forward (DF) mode and Compress and Forward (CF) mode are employed to the system. In the cooperative system, relays function to transmit the delivered signal to the destination. Each node in the system could play as the source station, the relay and the destination station. Currently, the issue of privacy and security are seriously requested in the communication. There could be the eavesdroppers pre-tend as the relay to steal the message. Hence, the secrecy protection becomes important. In the higher layer, the encryption scheme is applied to protect the message. However, it is difficult for those devices with low computing resources, the example of IoT (Internet of Things). With Shannon Theory, a secure communication could be supported with a positive secrecy rate. Hence, secure cooperative communication could be possible if there exist a positive secrecy rate between the two ends in the transmissions. Base on the secrecy rate analysis, the maximum secrecy rate is the initial step toward a secure communication. In the cooperative system, the delivered signal could be transmitted via relays. Hence, the path from the source to the destination could be a huge combination. With the exhaustive method to find the optimal secrecy rate could be realized. Hence, in this work, the numerical experiment, the AF and DF mode cooperative mode is adopted.
The prominence of the wireless communication has been urging the monotonically increasing demand of security and privacy. In wireless systems, the notion of perfect secrecy of information with respect to illegitimate nodes can be ensured via physical layer security (PLS) techniques. Unfortunately, they can be made less effective if source- eavesdropper wiretap channel is better than the main source-receiver channel. The various node cooperation schemes can be employed to combat this limitation where a relay node assists the communication to improve the performance significantly. In this paper, a four node wireless communication system consisting of a source, a destination, a relay and an eavesdropper as wire-tapper has been considered. The performance of the traditional cooperation schemes in terms of secrecy rate has been investigated with a different scenario where relay node helps the eavesdropper to deteriorate the secrecy rate. In addition, since legitimate receiver can overhear the transmission of relay, it favours the achievable secrecy rate. We formulate an analytical expression of conditional secrecy outage probability for the investigated system. From the obtained simulation results, it has been observed that secrecy rate is monotonically increases with path loss index. Furthermore, the proper selection of the system parameters leads to enhance the secrecy performance of the system even if relay pertains to degrade the performance. Amplify-and-forward, cooperation, decode-and-Forward, secrecy rate, relay.
Physical layer security is an attractive security mechanism, which exploits the randomness characteristics of wireless transmission channel to achieve security. However, it is hampered by the limitation of the channel condition that the main channel must be better than the eavesdropper channel. To alleviate the limitation, cooperative communication is introduced. Few studies have investigated the physical layer security of the relay transmission model. In this paper, we performed some experiments to evaluate the physical layer security of a cooperative communication system, with a relay operating in decode-and-forward (DF) cooperative mode, selfish and malicious behavior in real non-ideal transmission environment. Security performance is evaluated in terms of the probability of non-zero secrecy capacity. Experiments showed some different results compared to theoretical simulation: (1) to achieve the maximum secrecy capacity, the optimal relay power according to the experiments result is larger than that of ideal theoretical results under both cooperative and selfish behavior relay; (2) the relay in malicious behavior who forwards noise to deteriorate the main channel may deteriorate the eavesdropper channel more seriously than the main channel; (3) the optimal relay positions under cooperative and selfish behavior relay cases are both located near the destination because of non-ideal transmission.
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.
Privacy and security have an increasingly important role in wireless networks. A secure communication enables a legitimate destination to successfully retrieve information sent by a source, while it disables the eavesdropper (illegitimate destination) to interpret the intercepted information. Physical (PHY) layer security approaches for wireless communications can prevent eavesdropping without encryption. It exploits the physical characteristics of the wireless channel in order to transmit messages securely. They are typically feasible when the source-destination channel is better than the source-eavesdropper channel. Cooperative schemes are a means to improve the performance of secure wireless communications. We propose an improved relay selection scheme, based on source-eavesdropper channel SNR restriction, that will guarantee the best secrecy rate at the destination under QoS condition. Performance has been studied in terms of secrecy rate, outage probability and average error probability. Simulations shows that the proposed scheme outperforms in terms of the secrecy rate at the destination when compared to techniques in the literature.